tag:theconversation.com,2011:/au/topics/greenland-4062/articles
Greenland – The Conversation
2024-02-26T13:39:14Z
tag:theconversation.com,2011:article/217253
2024-02-26T13:39:14Z
2024-02-26T13:39:14Z
What ancient farmers can really teach us about adapting to climate change – and how political power influences success or failure
<figure><img src="https://images.theconversation.com/files/576820/original/file-20240220-22-4dkk2z.jpg?ixlib=rb-1.1.0&rect=15%2C15%2C5160%2C3391&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A farmer paddles to his fields on an artificial island among canals, part of an ancient Aztec system known as chinampas, in 2021. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/ae1d688be96145e38f16681367992bca?ext=true">AP Photo /Marco Ugarte</a></span></figcaption></figure><p>In dozens of archaeological discoveries around the world, from the once-successful reservoirs and canals of <a href="https://doi.org/10.1016/j.jaa.2020.101166">Angkor Wat</a> in Cambodia to the deserted <a href="https://doi.org/10.1073/pnas.2209615120">Viking colonies</a> of Greenland, new evidence paints pictures of civilizations struggling with unforeseen climate changes and the reality that their farming practices had become unsustainable.</p>
<p>Among these discoveries are also success stories, where ancient farming practices helped civilizations survive the hard times. </p>
<p><a href="https://doi.org/10.1073/pnas.2209615120">Zuni farmers</a> in the southwestern United States made it through long stretches of extremely low rainfall between A.D. 1200 and 1400 by embracing small-scale, decentralized irrigation systems. <a href="https://www.ucpress.edu/book/9780520343757/the-scarcity-slot">Farmers in Ghana</a> coped with severe droughts from 1450 to 1650 by planting indigenous African grains, like drought-tolerant pearl millet. </p>
<p>Ancient practices like these are gaining new interest today. As countries face unprecedented heat waves, storms and melting glaciers, some farmers and international development organizations are reaching deep into the agricultural archives to revive these ancient solutions.</p>
<figure class="align-center ">
<img alt="A canal running through a mountain side with snowy peaks in the background." src="https://images.theconversation.com/files/576825/original/file-20240220-18-dywyn0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576825/original/file-20240220-18-dywyn0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576825/original/file-20240220-18-dywyn0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576825/original/file-20240220-18-dywyn0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576825/original/file-20240220-18-dywyn0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576825/original/file-20240220-18-dywyn0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576825/original/file-20240220-18-dywyn0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An ancient irrigation method used by the Moors involving water channels is being revisited in Spain.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/water-channel-for-irrigation-known-as-an-acequia-sierra-news-photo/525482563?adppopup=true">Geography Photos/Universal Images Group via Getty Images</a></span>
</figcaption>
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<p>Drought-stricken farmers in Spain have reclaimed medieval <a href="https://www.nytimes.com/2023/07/19/world/europe/spain-drought-acequias.html">Moorish irrigation</a> technology. International companies hungry for carbon offsets have paid big money for <a href="https://www.wsj.com/articles/ancient-farming-practice-draws-cash-from-carbon-credits-a803aee1">biochar made using pre-Columbian</a> Amazonian production techniques. Texas ranchers have turned to <a href="https://www.theguardian.com/environment/2023/may/29/rio-grande-valley-farmers-study-ancient-technique-cover-cropping-climate-crisis">ancient cover cropping</a> methods to buffer against unpredictable weather patterns.</p>
<p>But grasping for ancient technologies and techniques without paying attention to historical context misses one of the most important lessons ancient farmers can reveal: Agricultural sustainability is as much about power and sovereignty as it is about soil, water and crops.</p>
<p>I’m an archaeologist who studies <a href="https://doi.org/10.1007/s10814-019-09138-5">agricultural sustainability</a> in the past. <a href="https://doi.org/10.1073/pnas.1914211117">Discoveries in recent years</a> have shown how <a href="https://doi.org/10.1016/j.quascirev.2015.07.022">the human past</a> is <a href="https://doi.org/10.1146/annurev-anthro-092611-145941">full of people</a> who <a href="https://doi.org/10.1038/s41586-021-03190-2">dealt with climate change</a> in both sustainable and unsustainable ways. Archaeologists are finding that ancient sustainability was tethered closely to politics. However, these dynamics are often forgotten in discussions of sustainability today.</p>
<h2>Maya milpa farming: Forest access is essential</h2>
<p>In the tropical lowlands of Mexico and Central America, Indigenous Maya farmers have been practicing milpa agriculture for thousands of years. Milpa farmers adapted to drought by gently steering forest ecology through <a href="https://doi.org/10.1890/120344">controlled burns</a> and careful <a href="https://books.google.com/books?hl=en&lr=&id=gVyTDAAAQBAJ&oi=fnd&pg=PP1&dq=Maya+milpa+forest+garden&ots=1ozG6sVYyg&sig=KZNXSDWX2ZR_Em7qGY37CqdeIG0#v=onepage&q=Maya%20milpa%20forest%20garden&f=false">woodland conservation</a>.</p>
<p>The knowledge of milpa farming empowered many <a href="https://books.google.com/books?hl=en&lr=&id=cX7SEAAAQBAJ&oi=fnd&pg=PP1&dq=chan+Cynthia+robin&ots=yErzYIWFsz&sig=vNrtsYW7IC0X2UnieHxor4Hiiiw#v=onepage&q=chan%20Cynthia%20robin&f=false">rural farmers</a> to navigate climate changes during the notorious <a href="https://doi.org/10.1073/pnas.1114838109">Maya Collapse</a> – two centuries of <a href="https://doi.org/10.1073/pnas.1419133112">political disintegration and urban depopulation</a> between A.D. 800 to 1000. Importantly, later Maya political leaders worked with farmers to keep this flexibility. Their light-handed approach is still legible in the artifacts and settlement patterns of <a href="https://books.google.com/books/about/The_Political_Geography_of_the_Yucatan_M.html?id=52BlAAAAMAAJ">post-Collapse farming communities</a> and preserved in the flexible <a href="https://doi.org/10.1007/s10745-020-00134-8">tribute schedules</a> for Maya farmers documented by 16th century Spanish monks.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/96rIEVptFwo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Maya farmers and researchers explain milpa farming.</span></figcaption>
</figure>
<p>In <a href="https://www.ucpress.edu/book/9780520395879/rooting-in-a-useless-land">my book</a>, “Rooting in a Useless Land: Ancient Farmers, Celebrity Chefs, and Environmental Justice in Yucatán,” I trace the deep history of the Maya milpa. Using archaeology, I show how ancient farmers adapted milpa agriculture in response to centuries of drought and political upheaval.</p>
<p>Modern Maya milpa practices began drawing public attention a few years ago as <a href="https://www.cimmyt.org/news/helping-farming-families-thrive-while-fighting-climate-change-in-mexico/">international development organizations</a> partnered with celebrity chefs, like <a href="https://www.cimmyt.org/es/noticias/el-restaurante-noma-llega-a-tulum-y-utilizara-maices-sustentables-de-yaxunah-2/">Noma’s René Redzepi</a>, and embraced the concept. </p>
<p>However, these groups condemned the traditional milpa practice of burning new areas of forest as unsustainable. They instead promoted a “no-burn” version to grow certified <a href="https://www.nytimes.com/2017/05/23/dining/noma-tulum-pete-wells-mexico-rene-redzepi.html">organic maize for high-end restaurants</a>. Their no-burn version of milpa relies on fertilizers to grow maize in a fixed location, rather than using controlled fire ecology to manage soil fertility across vast forests.</p>
<p>The result restricted the traditional practices Maya farmers have used for centuries. It also fed into a modern political threat to traditional Maya milpa farming: land grabs. </p>
<p>Traditional milpa agriculture requires a lot of forested land, since farmers need to relocate their fields every couple of years. But that need for forest is at odds with hotel companies, industrial cattle ranches and green energy developers who want cheap land and see Maya milpa forest management practices as inefficient. No-burn milpa eases this conflict by locking maize agriculture into one small space indefinitely, instead of spreading it out through the forest over generations. But it also changes tradition. </p>
<p>Maya milpa farmers are now fighting to practice their ancient agricultural techniques, not because they’ve forgotten or lost those techniques, but because <a href="https://doi.org/10.1111/joac.12520">neocolonial</a> land <a href="https://doi.org/10.1080/03066150.2016.1215305">privatization policies</a> actively undermine farmers’ ability to manage woodlands as their ancestors did. </p>
<p>Milpa farmers are increasingly left to either adopt a rebranded version of their heritage or quit farming all together – as many have done.</p>
<h2>Mexico’s fragile artificial islands: Threats from development</h2>
<p>When I look to the work of other archaeologists investigating ancient agricultural practices, I see these same entanglements of power and sustainability.</p>
<p>In central Mexico, <a href="https://www.jstor.org/stable/24931564?casa_token=Mnjg8lpMxdEAAAAA:xtiTRUNdJVlBTAR3voVS3IszoyqO-VSb8MSohjUlxpYEdNtVKu0QPefJMjiSyvobBMO94-zcDj2E6DOXbNoUl1d-MNm3UO6TDKVsG4JLVxpWkHtFIg">chinampas</a> are ancient systems of artificial islands and canals. They have enabled farmers to cultivate food in wetlands for centuries. </p>
<p>The continuing existence of chinampas is a legacy of deep ecological knowledge and a resource enabling communities to feed themselves.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/571516/original/file-20240125-21-sq17hw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571516/original/file-20240125-21-sq17hw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=421&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571516/original/file-20240125-21-sq17hw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=421&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571516/original/file-20240125-21-sq17hw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=421&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571516/original/file-20240125-21-sq17hw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=529&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571516/original/file-20240125-21-sq17hw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=529&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571516/original/file-20240125-21-sq17hw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=529&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Chinampa techniques use canals and artificial islands. This photo shows one in 1912.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Chinampas.jpg">Karl Weule, Leitfaden der Voelkerkunde via Wikimedia</a></span>
</figcaption>
</figure>
<figure class="align-center ">
<img alt="A well-maintained farming island among canals near Mexico City." src="https://images.theconversation.com/files/571517/original/file-20240125-19-ug1yul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571517/original/file-20240125-19-ug1yul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571517/original/file-20240125-19-ug1yul.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571517/original/file-20240125-19-ug1yul.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571517/original/file-20240125-19-ug1yul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571517/original/file-20240125-19-ug1yul.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571517/original/file-20240125-19-ug1yul.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The chinampas of Xochimilco are a UNESCO world heritage site today, but development expanding from Mexico City has put their survival in danger.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/sergiosf/12546098673">Sergei Saint via Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>But archaeology has revealed that generations of sustainable chinampa management could be overturned almost overnight. That happened when the expansionist Aztec Empire decided to <a href="https://doi.org/10.1017/S0003598X00101164">re-engineer Lake Xaltocan</a> for salt production in the 14th century and rendered its chinampas unusable.</p>
<p>Today, the future of chinampa agriculture hinges on a pocket of protected fields <a href="https://www.nationalgeographic.co.uk/history-and-civilisation/2022/07/in-mexico-city-the-pandemic-revived-aztec-era-island-farms">stewarded by local farmers</a> in the marshy outskirts of Mexico City. These fields are <a href="https://doi.org/10.1016/j.jrurstud.2021.07.018">now at risk</a> as demand for housing drives informal settlements into the chinampa zone.</p>
<h2>Andean raised fields: A story of labor exploitation</h2>
<p>Traditional Andean agriculture in South America incorporates a diverse range of ancient cultivation techniques. One in particular has a complicated history of attracting revival efforts.</p>
<p>In the 1980s, government agencies, <a href="https://www.penn.museum/documents/publications/expedition/30-3/Raised.pdf">archaeologists</a> and development organizations spent a fortune trying to persuade Andean farmers to <a href="https://www.taylorfrancis.com/books/mono/10.4324/9781315810997/inventing-indigenous-knowledge-lynn-swartley">revive raised field farming</a>. Ancient raised fields had been found around Lake Titicaca, on the border of Peru and Bolivia. These groups became convinced that this relic technology could curb hunger in the Andes by enabling back-to-back potato harvests with no need for fallowing.</p>
<p>But Andean farmers had no connection to the labor-intensive raised fields. The practice had been abandoned even before the rise of Inca civilization in the 13th century. The effort to revive ancient raised field agriculture collapsed.</p>
<figure class="align-center ">
<img alt="A view from a plane shows the outlines where fields were raised." src="https://images.theconversation.com/files/571518/original/file-20240125-21-4uobzz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571518/original/file-20240125-21-4uobzz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571518/original/file-20240125-21-4uobzz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571518/original/file-20240125-21-4uobzz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571518/original/file-20240125-21-4uobzz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=551&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571518/original/file-20240125-21-4uobzz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=551&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571518/original/file-20240125-21-4uobzz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=551&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An aerial photograph shows pre-Colombian raised fields in Bolivia.</span>
<span class="attribution"><a class="source" href="https://www.eurekalert.org/multimedia/861590">Umberto Lombardo, University of Bern, Switzerland</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Since then, more <a href="https://doi.org/10.1016/j.jaa.2005.03.002">archaeological discoveries</a> around Lake Titicaca have suggested that ancient farmers were forced to work the raised fields <a href="https://doi.org/10.1016/j.jaa.2004.08.001">by the expansionist Tiwanaku empire</a> during its peak between AD 500 and 1100. Far from the politically neutral narrative promoted by development organizations, the raised fields were not there to help farmers feed themselves. They were a technology for exploiting labor and extracting surplus crops from ancient Andean farmers.</p>
<h2>Respecting ancient practices’ histories</h2>
<p>Reclaiming <a href="https://www.soulfirefarm.org/media/farming-while-black/">ancestral farming</a> techniques can be a <a href="https://www.icollectiveinc.org/">step toward sustainable food systems</a>, especially when descendant communities lead their reclamation. The world can, and I think should, reach back to recover agricultural practices from our collective past.</p>
<p>But we can’t pretend that those practices are apolitical.</p>
<p>The Maya milpa farmers who continue to practice controlled burns in defiance of land privatizers understand the value of ancient techniques and the threat posed by political power. So do the Mexican chinampa farmers working to restore local food to disenfranchised urban communities. And so do the Andean farmers refusing to participate in once-exploitive raised field rehabilitation projects. </p>
<p>Depending on how they are used, ancient agricultural practices can either reinforce social inequalities or create more equitable food systems. Ancient practices aren’t inherently good – it takes a deeper commitment to just and equitable food systems to make them sustainable.</p><img src="https://counter.theconversation.com/content/217253/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chelsea Fisher has received research funding from the National Science Foundation, the Wenner-Gren Foundation, and the Fulbright-Hays Program.</span></em></p>
Agricultural sustainability is as much about power and sovereignty as it is about soil, water and crops.
Chelsea Fisher, Assistant Professor of Anthropology, University of South Carolina
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/223768
2024-02-20T16:52:21Z
2024-02-20T16:52:21Z
A single Antarctic heatwave or storm can noticeably raise the sea level
<p>A heat wave in Greenland and a storm in Antarctica. These kinds of individual weather “events” are increasingly being supercharged by a warming climate. But despite being short-term events they can also have a much longer-term effect on the world’s largest ice sheets, and may even lead to tipping points being crossed in the polar regions.</p>
<p>We have <a href="https://www.nature.com/articles/s43017-023-00509-7.epdf?sharing_token=EJZ02zq3kFQO4XKwZVTBLdRgN0jAjWel9jnR3ZoTv0NlXBkse_V2fGVmyGVwGFcXe8LM4zjSaytnzbxkpU3vleMHbbCbjypxjcJ3p1wJddVoe1nKU4klsbQfMwCvE-m9plem7c8GygdxBfIr9KNkFEXV23v6oF28LZQkvsWpQm4%3D">just published</a> research looking at these sudden changes in the ice sheets and how they may impact what we know about sea level rise. One reason this is so important is that the global sea level is predicted to rise by anywhere between 28 cm and 100cm by the year 2100, according to <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf">the IPCC</a>. This is a huge range – 70 cm extra sea-level rise would affect many millions more people. </p>
<p>Partly this uncertainty is because we simply don’t know whether we’ll curb our emissions or continue with business as usual. But while possible social and economic changes are at least <a href="https://www.carbonbrief.org/explainer-how-shared-socioeconomic-pathways-explore-future-climate-change/">factored in</a> to the above numbers, the IPCC acknowledges its estimate does not take into account deeply uncertain ice-sheet processes. </p>
<h2>Sudden accelerations</h2>
<p>The sea is rising for two main reasons. First, the water itself is very slightly expanding as it warms, with this process responsible for <a href="https://theconversation.com/how-much-will-our-oceans-warm-and-cause-sea-levels-to-rise-this-century-weve-just-improved-our-estimate-166417">about a third</a> of the total expected sea-level rise. </p>
<p>Second, the world’s largest ice sheets in Antarctica and Greenland are melting or sliding into the sea. As the ice sheets and glaciers respond relatively slowly, the sea will also continue to rise for centuries.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Large glacier in mountains meeting the ocean" src="https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Elephant Foot Glacier in northern Greenland.</span>
<span class="attribution"><span class="source">Nicolaj Larsen / shutterstock</span></span>
</figcaption>
</figure>
<p>Scientists have long known that there is a potential for sudden accelerations in the rate at which ice is lost from Greenland and Antarctica which could cause considerably more sea-level rise: perhaps a metre or more in a century. Once started, this would be impossible to stop. </p>
<p>Although there is a lot of uncertainty over how likely this is, there is some evidence that it happened <a href="https://www.nature.com/articles/nature17145">about 130,000 years ago</a>, the last time global temperatures were anything close to the present day. We cannot discount the risk. </p>
<p>To improve predictions of rises in sea level we therefore need a clearer understanding of the Antarctic and Greenland ice sheets. In particular, we need to review if there are weather or climate changes that we can already identify that might lead to abrupt increases in the speed of mass loss.</p>
<h2>Weather can have long-term effects</h2>
<p><a href="https://www.nature.com/articles/s43017-023-00509-7.epdf?sharing_token=EJZ02zq3kFQO4XKwZVTBLdRgN0jAjWel9jnR3ZoTv0NlXBkse_V2fGVmyGVwGFcXe8LM4zjSaytnzbxkpU3vleMHbbCbjypxjcJ3p1wJddVoe1nKU4klsbQfMwCvE-m9plem7c8GygdxBfIr9KNkFEXV23v6oF28LZQkvsWpQm4%3D">Our new study</a>, involving an international team of 29 ice-sheet experts and published in the journal Nature Reviews Earth & Environment, reviews evidence gained from observational data, geological records, and computer model simulations. </p>
<p>We found several examples from the past few decades where weather “events” – a single storm, a heatwave – have led to important long-term changes. </p>
<p>The ice sheets are built from millennia of snowfall that gradually compresses and starts to flow towards the ocean. The ice sheets, like any glacier, respond to changes in the atmosphere and the ocean when the ice is in contact with sea water. </p>
<p>These changes could take place over a matter of hours or days or they may be long-term changes from months to years or thousands of years. And processes may interact with each other on different timescales, so that a glacier may gradually thin and weaken but remain stable until an abrupt short-term event pushes it over the edge and it rapidly collapses. </p>
<p>Because of these different timescales, we need to coordinate collecting and using more diverse types of data and knowledge.</p>
<p>Historically, we thought of ice sheets as slow-moving and delayed in their response to climate change. In contrast, our research found that these huge glacial ice masses respond in far quicker and more unexpected ways as the climate warms, similarly to the frequency and intensity of hurricanes and heatwaves responding to changes with the climate. </p>
<p>Ground and satellite observations show that sudden heatwaves and large storms can have long-lasting effects on ice sheets. For example a heatwave in July 2023 meant at one point <a href="https://www.carbonbrief.org/guest-post-how-the-greenland-ice-sheet-fared-in-2023/">67% of the Greenland ice sheet surface</a> was melting, compared with around 20% for average July conditions. In 2022 unusually warm rain fell on the <a href="https://www.whoi.edu/oceanus/feature/a-cold-case-filed-conger-ice-shelf-collapse/">Conger ice shelf</a> in Antarctica, causing it to disappear almost overnight.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1679391326326980608"}"></div></p>
<p>These weather-driven events have long “tails”. Ice sheets don’t follow a simple uniform response to climate warming when they melt or slide into the sea. Instead their changes are punctuated by short-term extremes. </p>
<p>For example, brief periods of melting in Greenland can melt far more ice and snow than is replaced the following winter. Or the catastrophic break-up of ice shelves along the Antarctic coast can rapidly unplug much larger amounts of ice from further inland. </p>
<p>Failing to adequately account for this short-term variability might mean we underestimate how much ice will be lost in future.</p>
<h2>What happens next</h2>
<p>Scientists must prioritise research on ice-sheet variability. This means better ice-sheet and ocean monitoring systems that can capture the effects of short but extreme weather events. </p>
<p>This will come from new satellites as well as field data. We’ll also need better computer models of how ice sheets will respond to climate change. Fortunately there are already some promising global <a href="http://imbie.org/">collaborative</a> <a href="https://climate-cryosphere.org/about-ismip6/">initiatives</a>.</p>
<p>We don’t know exactly how much the global sea level is going to rise some decades in advance, but understanding more about the ice sheets will help to refine our predictions.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 30,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/223768/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Edward Hanna receives funding from the UK's Natural Environment Research Council.
The research was sponsored by the World Climate Research Programme’s Climate and Cryosphere project, the International Arctic Science Committee, and the Scientific Committee on Antarctic Research, and resulted from a collaboration following an Ice Sheet Mass Balance and Sea Level expert group workshop.</span></em></p><p class="fine-print"><em><span>Ruth Mottram received funding for this work from the European Union, Horizon Europe Funding Programme for research and innovation under grant agreement Nr. 101060452 and from the Novo Nordisk Foundation for the Challenge project PRECISE (Predicting Ice Sheets on Earth), grant NNF23OC0081251.
</span></em></p>
To narrow our predictions of global sea level rise, we need to know more about these sudden ‘non-linear’ changes to ice sheets.
Edward Hanna, Professor of Climate Science and Meteorology, University of Lincoln
Ruth Mottram, Climate Scientist, National Centre for Climate Research, Danish Meteorological Institute
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/215928
2023-10-18T16:30:09Z
2023-10-18T16:30:09Z
What will happen to the Greenland ice sheet if we miss our global warming targets
<figure><img src="https://images.theconversation.com/files/554571/original/file-20231018-17-rfjr6n.JPG?ixlib=rb-1.1.0&rect=19%2C0%2C4372%2C2146&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Bryn Hubbard</span></span></figcaption></figure><p>It’s hard to overstate how crucial Greenland, and its kilometres-thick ice layer, is to climate change. If all that ice melted, the sea would rise by about seven metres – the height of a house. </p>
<p>But what happens if we fail to limit warming to 1.5°C (as looks increasingly likely)? And what happens if we do subsequently manage to rectify that “overshoot” and bring temperatures back down? A team of researchers writing in the journal <a href="https://www.nature.com/articles/s41586-023-06503-9">Nature</a> have now published a study exploring these questions.</p>
<p>In a nutshell, their work shows the worst case scenario of ice sheet collapse and consequent sea-level rise can be avoided – and even partly reversed – if we manage to reduce the global temperatures projected for after 2100. Moreover, the lower and sooner those temperatures fall, the more chance there is of minimising that ice melt and sea-level rise.</p>
<p>We already know that the Greenland ice sheet is losing more than <a href="https://essd.copernicus.org/articles/15/1597/2023/">300 billion cubic metres of ice per year</a>, currently driving global sea levels up by a little less than a millimetre per year. One major worry is that further warming could cross critical thresholds, sometimes referred to as “tipping points”. For example, as the air warms more ice will melt, lowering the elevation of the ice surface and hence exposing it to warmer air temperatures and more melting – even without continued atmospheric warming. </p>
<p>Although far more complex and nuanced in reality, it is feedback processes such as this which dictate that global warming be limited to 1.5°C above pre-industrial levels in order to avoid catastrophes, such as wholescale ice-sheet collapse.</p>
<h2>How to simulate a huge ice sheet in a computer</h2>
<p>It is critically important that we are able to predict how the Greenland ice sheet will respond to future warming. To achieve this, researchers generally use computer models of ice motion. In essence, these divide the ice sheet into tens of thousands of 3D segments and apply physical laws of ice motion to compute how each segment changes over thousands of individual time steps, factoring in things like anticipated climatic change, ice thickness, ice slope and the temperature of the ice interior and ice base.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Small tents, huge ice sheet" src="https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=348&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=348&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=348&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Research field camp on the crevassed surface of the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Bryn Hubbard</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>However, these projections are subject to substantial uncertainties. It’s tough to know exactly how ice moves over bedrock, or what its internal temperature might be. And the climate is made up of many moving parts. Atmospheric and oceanic circulations may also change radically over the thousands or tens of thousands of years it takes for the ice sheet to settle in to a new equilibrium.</p>
<p>In the face of such challenges, a team of researchers led by Nils Bochow of the Arctic University in Norway have published their new study. They ran two independent state-of-the-art computer programs that were able to simulate how the Greenland ice sheet would respond to various possible levels of global warming, over tens of thousands of years. To mimic the effects of overshooting the critical 1.5°C threshold, they include a gradual warming trajectory to a “peak” temperature, followed by a period during which temperature stabilises to a generally lower final “convergence temperature”. </p>
<h2>Good news and bad news</h2>
<p>The results are fascinating. If temperatures peak at 2°C or so, and remain there, then the models – as expected – predict substantial ice sheet collapse after several thousands of years. </p>
<p>However, things change if warming is seriously mitigated post-2100. In those models, inertia in the ice sheet’s response – a bit like the time it takes for a ripple to settle down as it passes across a pond – means that an overshoot is at least partly reversible as long as temperatures are quickly brought back down. </p>
<p>For example, if temperature stabilises by the year 2200 at less than 1.5°C of warming, then the ice sheet should remain smaller than at present, but stable. This is the case irrespective of how far (within reason) peak temperatures overshot 1.5°C in the year 2100. In such cases the sea rise would likely be restricted to a metre or so. </p>
<p>However, such a recovery becomes impossible if it takes too long to get temperatures down or if the convergence temperature remains too high. In those scenarios, ice-sheet collapse and substantial sea-level rise become all but inevitable.</p>
<p>Perhaps the very worst can be avoided then, if we continue to work to reduce global temperatures right through this century and next. Although heartening to some degree, these projections are subject to substantial uncertainty and there is more work to do. In this regard, the authors are at pains to note that their results are not necessarily specific predictions but rather provide insight into possible pathways. </p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 20,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/215928/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bryn Hubbard receives funding from the UK's Natural Environment Research Council. He is affiliated with the Centre for Glaciology at Aberystwyth University. </span></em></p>
The ice will survive if temperatures are soon brought back down – new study.
Bryn Hubbard, Professor of Glaciology, Aberystwyth University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/206236
2023-08-21T15:40:48Z
2023-08-21T15:40:48Z
To predict future sea level rise, we need accurate maps of the world’s most remote fjords
<figure><img src="https://images.theconversation.com/files/543613/original/file-20230821-93007-prjkm7.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4114%2C1492&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The 10km wide Petermann Fjord in northern Greenland. The author's icebreaker ship is a small dot in the middle. The cliffs on either side are a kilometre high. In the distance is the 'ice tongue' of the glacier flowing into the fjord.</span> <span class="attribution"><span class="source">Martin Jakobsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Understanding how glaciers interact with the ocean is akin to piecing together a colossal jigsaw puzzle. And on various icebreaker expeditions to some of the most remote fjords in northern Greenland, colleagues and I have showed that the shape of the seafloor is one of the key pieces of that puzzle.</p>
<p>To understand why the seabed is so important, we have to look at the glaciers themselves and what is causing them to retreat or even disappear. The large glaciers that meet the ocean in Greenland and Antarctica balance their mass over time largely in pace with the climate. When it snows or rains they accumulate ice, and they lose ice to melting and calving – the process where chunks of ice break off and eventually melt away into the sea. </p>
<p>But over the past few decades they are <a href="https://theconversation.com/greenland-has-lost-3-8-trillion-tonnes-of-ice-since-1992-127752">losing mass at an accelerated pace</a>, with more icebergs calving into the ocean and more ice being melted from below by relatively warm seawater. </p>
<p>Estimating how much mass will be lost is often highlighted as glaciology’s grand challenge as it constitutes a <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf">large uncertainty</a> in our predictions of future sea-level rise. To hone our predictions, it is crucial to find the areas where warmer ocean water reaches the these glaciers. </p>
<p>Most glaciers in Greenland drain into fjords in which the waters near the surface are very cold, heavily influenced by meltwater from the glaciers. Some fjords also allow in warmer water of Atlantic origin, which is saltier and therefore heavier so it enters the fjords at a greater depth.</p>
<p>The shape and depth (or “bathymetry”) of the seafloor determines whether this warmer water can reach the glaciers and cause them to melt. These fjords may have particularly complex bathymetry as they themselves were formed by glaciers which also eroded the seabed. While the inner parts can be a kilometre deep, a shallower “sill” at the entrance (formed when eroded materials accumulate or from resistant bedrock) can act as a shield against inflowing warmer water.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="diagram of fjord" src="https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=278&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=278&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=278&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=349&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=349&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=349&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diagram of a fjord showing a sill that keeps out the warmer ocean water (note in Greenland the fjords are fed by glaciers not rivers).</span>
<span class="attribution"><a class="source" href="https://www.amap.no/">AMAP</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>That’s why mapping these fjords is one of the most critical steps in <a href="https://www.sciencedirect.com/science/article/pii/S2590332220305923">assessing the future</a> of the glaciers that flow into them. This is unfortunately easier said than done, since many of these glaciers flow into some of the most remote areas of the world.</p>
<h2>Ireland-sized glacier, Manhattan-sized icebergs</h2>
<p>The Petermann Glacier – the largest in the northern part of the Greenland ice sheet – drains an area of <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL051634">about 74,000 square kilometres</a>, similar to the size of Ireland.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Annotated map of Greenland glaciers" src="https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=650&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=650&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=650&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=817&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=817&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=817&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some of the most northerly and inaccessible fjords on earth.</span>
<span class="attribution"><span class="source">Martin Jakobsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Petermann is one of a few glaciers around Greenland with a floating ice tongue extending tens of kilometres from where the glacier is grounded on the seafloor. These ice tongues may <a href="https://tc.copernicus.org/articles/7/647/2013/">act as a brakes</a> on the flow of ice into the sea, slowing down mass loss. </p>
<p>In 2010, Petermann made headlines when <a href="https://earthobservatory.nasa.gov/images/45112/ice-island-calves-off-petermann-glacier">a huge chunk broke off</a> and formed an iceberg four times the size of Manhattan island. This was followed by another huge calving two years later. While calving is a natural process, these unusually large events were likely influenced by warmer waters from the Atlantic <a href="https://tos.org/oceanography/article/the-ice-shelf-of-petermann-gletscher-north-greenland-and-its-connection-to">melting the tongue from below</a>, making it thinner and more prone to break. </p>
<p>In 2015 colleagues and I <a href="https://www.nature.com/articles/s41467-018-04573-2">mapped the entire seabed of Petermann Fjord</a> for the first time. We found the entrance was still very deep: 443 metres – as deep as the Empire State Building is tall. Deep enough for that warm, heavy, salty glacier-melting Atlantic water to enter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Ship in front of huge cliffs" src="https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The icebreaker Oden in Petermann Fjord. The same ship appears as a tiny dot in the image at the top of the article.</span>
<span class="attribution"><span class="source">Martin Jakobsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>We next wanted to compare Petermann to the Ryder Glacier to its northeast, which has been more stable since at least the 1950s. Was it kept in place by a shallow fjord entrance keeping out warmer water? </p>
<p>At the time, no ship had ever entered Sherard Osborn Fjord where Ryder Glacier drains, because the sea ice in that region is the toughest in the entire Arctic Ocean. Therefore, nothing at all was known about the seafloor. Ryder Glacier became the target for our next expedition with icebreaker Oden in 2019.</p>
<h2>Shielded from warmer water</h2>
<p>Thick ice in the narrow passage separating Ellesmere Island from Greenland made it hard to even get to Sherard Osborn Fjord. And entering the fjord was a true challenge, as large icebergs that had calved from the ice tongue floated around and occasionally blocked the entire entrance.</p>
<p>It turned out the fjord has a <a href="https://www.nature.com/articles/s43247-020-00043-0">prominent shallow sill in front of Ryder Glacier</a>. This sill shields the glacier from warmer subsurface Atlantic water, which appears to explain why it has behaved very differently compared to Petermann.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Annotated image of glacier, fjord and seabed." src="https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=409&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=409&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=409&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=514&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=514&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=514&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An underwater sill in front of Ryder Glacier shields it from inflowing warmer water from the Atlantic.</span>
<span class="attribution"><span class="source">Martin Jakobsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The bathymetry of both Petermann and Sherard Osborn fjords has now been incorporated into the <a href="https://seabed2030.org/">Seabed 2030 Project</a>, which aims to completely map the world’s ocean floor before the end of the decade. Knowing more about the seabed, and the glaciers that flow into the sea, will in turn help us to sustainably manage the ocean and, ultimately, the planet. </p>
<p>The are more completely unmapped areas in North Greenland. In 2024, we are planning another expedition with icebreaker Oden even further north to Victoria Fjord, where C.H. Ostenfeld Glacier drains. This glacier recently lost its floating ice tongue and whether or not Atlantic water makes into the fjord remains to be seen. </p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
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<p class="fine-print"><em><span>Martin Jakobsson is Co-Head of Arctic and North Pacific Center at Seabed 2030, a project funded by the Nippon Foundation to map the entire global seabed.</span></em></p>
Some of the world’s biggest glaciers flow into fjords in Greenland and we need to know what they’ll bump into on the seabed.
Martin Jakobsson, Professor of Marine Geology and Geophysics, Stockholm University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/209018
2023-07-20T18:00:01Z
2023-07-20T18:00:01Z
When Greenland was green: Ancient soil from beneath a mile of ice offers warnings for the future
<figure><img src="https://images.theconversation.com/files/537577/original/file-20230715-21-gwfd9c.jpg?ixlib=rb-1.1.0&rect=0%2C352%2C4733%2C3053&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Water and sediment pour off the melting margin of the Greenland ice sheet.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/qinnguata-kuussua-river-russell-glacier-greenland-royalty-free-image/604573407">Jason Edwards/Photodisc via Getty Images</a></span></figcaption></figure><p>About 400,000 years ago, large parts of Greenland were ice-free. Scrubby tundra basked in the Sun’s rays on the island’s northwest highlands. Evidence suggests that a <a href="https://www.science.org/doi/10.1126/science.1141758">forest of spruce</a> trees, buzzing with insects, covered the southern part of Greenland. Global sea level was much higher then, between 20 and 40 feet <a href="https://www.science.org/doi/10.1126/science.aaa4019">above today’s levels</a>. Around the world, land that today is home to hundreds of millions of people was under water.</p>
<p>Scientists have known for awhile that the Greenland ice sheet had mostly disappeared at some point in the <a href="https://www.nature.com/articles/nature20146">past million years</a>, but not precisely when. </p>
<p>In a new study in the <a href="http://www.science.org/doi/10.1126/science.ade4248">journal Science</a>,
we determined the date, using frozen soil <a href="https://www.campcentury.org/learning/podcasts">extracted during the Cold War</a> from beneath a nearly mile-thick section of the Greenland ice sheet. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/CYfSphNHOm8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A brief look at the evidence beneath Greenland’s ice sheet and the lessons its holds.</span></figcaption>
</figure>
<p>The timing – about 416,000 years ago, with largely ice-free conditions lasting for as much as 14,000 years – is important. At that time, Earth and its <a href="https://www.smithsonianmag.com/science-nature/how-drastic-ecological-change-led-leap-forward-behavior-weapons-and-tools-180976101/">early humans</a> were going through one of the longest interglacial periods since ice sheets first covered the high latitudes 2.5 million years ago. </p>
<p>The length, magnitude and effects of that natural warming can help us understand the Earth that modern humans are now creating for the future.</p>
<h2>A world preserved under the ice</h2>
<p>In July 1966, American scientists and U.S. Army engineers completed a six-year effort to <a href="https://blogs.egu.eu/divisions/cr/2022/01/28/camp-century-bottom-ice/">drill through the Greenland ice sheet</a>. The drilling took place at <a href="https://www.popsci.com/environment/us-army-arctic-city/">Camp Century</a>, one of the military’s most unusual bases – it was <a href="https://theconversation.com/the-us-army-tried-portable-nuclear-power-at-remote-bases-60-years-ago-it-didnt-go-well-164138">nuclear powered</a> and made up of a series of tunnels dug into the Greenland ice sheet.</p>
<p>The drill site in northwest Greenland was 138 miles from the coast and underlain <a href="https://icedrill.org/sites/default/files/Langway_2008_Early_polar_ice_cores.pdf">by 4,560 feet of ice</a>. Once they reached the bottom of the ice, the team kept drilling 12 more feet into the frozen, rocky soil below.</p>
<figure class="align-center ">
<img alt="A man in a fur-lined coat removes a long ice core about as wide as his hand" src="https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=487&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=487&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=487&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=612&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=612&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=612&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">George Linkletter, working for the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory, examines a piece of ice core in the science trench at Camp Century. The base was shut down in 1967.</span>
<span class="attribution"><span class="source">U.S. Army Photograph</span></span>
</figcaption>
</figure>
<p>In 1969, geophysicist Willi Dansgaard’s analysis of the ice core from Camp Century revealed for the first time the details of how Earth’s climate had <a href="https://www.science.org/doi/10.1126/science.166.3903.377">changed dramatically</a> over the last 125,000 years. Extended cold glacial periods when the ice expanded quickly gave way to warm interglacial periods when the ice melted and sea level rose, flooding coastal areas around the world.</p>
<p>For nearly 30 years, scientists paid little attention to the 12 feet of frozen soil from Camp Century. One study <a href="https://www.cambridge.org/core/journals/journal-of-glaciology/article/evidence-of-the-bedrock-beneath-the-greenland-ice-sheet-near-camp-century-greenland/6F87EC12C84FAFB5BEE3E4A044B52618">analyzed the pebbles</a> to understand the bedrock beneath the ice sheet. Another suggested intriguingly that the frozen soil <a href="https://www.jstor.org/stable/40511026">preserved evidence</a> of a time warmer than today. But with no way to date the material, few people paid attention to these studies. By the 1990s, the frozen soil core had vanished.</p>
<p>Several years ago, our Danish colleagues found the lost soil buried deep in a Copenhagen freezer, and we formed an <a href="https://www.campcentury.org/home">international team</a> to analyze this unique frozen climate archive. </p>
<p>In the uppermost sample, we found perfectly preserved <a href="https://theconversation.com/ancient-leaves-preserved-under-a-mile-of-greenlands-ice-and-lost-in-a-freezer-for-years-hold-lessons-about-climate-change-157105">fossil plants</a> – proof positive that the land far below Camp Century had been ice-free some time in the past – but when?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two microscope images show tiny plant fossils. One a moss stem and the other a sedge seed." src="https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=272&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=272&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=272&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=342&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=342&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=342&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Exquisitely preserved fossils of more than 400,000-year-old moss, on the left, and a sedge seed on the right, found in the soil core from beneath the Greenland ice sheet, help tell the story of what lived there when the ice was gone.</span>
<span class="attribution"><a class="source" href="https://www.campcentury.org/press/photos">Halley Mastro/University of Vermont</a></span>
</figcaption>
</figure>
<h2>Dating ancient rock, twigs and dirt</h2>
<p>Using samples cut from the center of the sediment core and prepared and analyzed in the dark so that the material retained an accurate memory of its last exposure to sunlight, we now know that the ice sheet covering northwest Greenland – nearly a mile thick today – <a href="http://www.science.org/doi/10.1126/science.ade4248">vanished during the extended natural warm period</a> known to climate scientists as <a href="https://www.sciencedirect.com/science/article/pii/S027737912200124X">MIS 11</a>, between 424,000 and 374,000 years ago. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A composite photograph of the sediment core showing the luminescence sample used to determine when Greenland was last ice-free beneath Camp Century." src="https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The uppermost sample of the Camp Century sub-ice sediment core tells a story of vanished ice and tundra life in Greenland 416,000 years ago.</span>
<span class="attribution"><a class="source" href="https://www.campcentury.org/press/photos">Andrew Christ/University of Vermont</a></span>
</figcaption>
</figure>
<p>To determine more precisely when the ice sheet melted away, one of us, <a href="https://www.usu.edu/geo/osl/">Tammy Rittenour</a>, used a technique known as luminescence dating.</p>
<p>Over time, minerals accumulate energy as radioactive elements like uranium, thorium, and potassium decay and release radiation. The longer the sediment is buried, the more radiation accumulates as trapped electrons. </p>
<p>In the lab, specialized instruments measure tiny bits of energy, released as light from those minerals. That signal can be used to calculate how long the grains were buried, since the last exposure to sunlight would have released the trapped energy.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/TpZVa7O863A?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How optically stimulated luminescence works.</span></figcaption>
</figure>
<p><a href="https://www.uvm.edu/cosmolab/">Paul Bierman’s laboratory</a> at the University of Vermont dated the sample’s last time near the surface in a different way, using rare radioactive isotopes of aluminum and beryllium.</p>
<p>These isotopes form when cosmic rays, originating far from our solar system, slam into the rocks on Earth. Each isotope has a different half-life, meaning it decays at a different rate when buried. </p>
<p>By measuring both isotopes in the same sample, glacial geologist <a href="https://andrewjchrist.wixsite.com/website">Drew Christ</a> was able to determine that melting ice had exposed the sediment at the land surface for less than 14,000 years. </p>
<p>Ice sheet models run by <a href="https://ig.utexas.edu/staff/benjamin-keisling/">Benjamin Keisling</a>, now incorporating our new knowledge that Camp Century was ice-free 416,000 years ago, show that Greenland’s ice sheet must have shrunk significantly then. </p>
<p>At minimum, the edge of the ice retreated tens to hundreds of miles around much of the island during that period. Water from that melting ice raised global sea level at least 5 feet and perhaps as much as 20 feet compared to today.</p>
<h2>Warnings for the future</h2>
<p>The ancient frozen soil from beneath Greenland’s ice sheet warns of trouble ahead.</p>
<p>During the MIS 11 interglacial, Earth was warm and ice sheets were restricted to the high latitudes, a lot like today. <a href="https://www.sciencedirect.com/science/article/pii/S027737912200124X">Carbon dioxide levels</a> in the atmosphere remained between 265 and 280 parts per million for about 30,000 years. MIS 11 lasted longer than most interglacials because of the impact of the shape of Earth’s orbit around the sun on solar radiation reaching the Arctic. Over these 30 millennia, that level of carbon dioxide triggered enough warming to melt much of the Greenland’s ice.</p>
<p>Today, our atmosphere contains 1.5 times more carbon dioxide than it did at MIS 11, around <a href="https://keelingcurve.ucsd.edu/">420 parts per million</a>, a concentration that has risen each year. Carbon dioxide traps heat, warming the planet. Too much of it in the atmosphere raises the global temperature, as the world is seeing now.</p>
<p>Over the past decade, as greenhouse gas emissions continued to rise, humans experienced the eight warmest years on record. July 2023 saw the <a href="https://public.wmo.int/en/media/news/preliminary-data-shows-hottest-week-record-unprecedented-sea-surface-temperatures-and">hottest week on record</a>, based on preliminary data. Such heat <a href="https://theconversation.com/whats-going-on-with-the-greenland-ice-sheet-its-losing-ice-faster-than-forecast-and-now-irreversibly-committed-to-at-least-10-inches-of-sea-level-rise-185590">melts ice sheets</a>, and the loss of ice further warms the planet as dark rock soaks up sunlight that bright white ice and snow once reflected.</p>
<figure class="align-center ">
<img alt="Meltwater pours over the Greenland ice sheet in a meandering channel." src="https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">At midnight in July, meltwater pours over the Greenland ice sheet in a meandering channel.</span>
<span class="attribution"><span class="source">Paul Bierman</span></span>
</figcaption>
</figure>
<p>Even if everyone stopped burning fossil fuels tomorrow, carbon dioxide levels in the atmosphere would <a href="https://www.nature.com/articles/nclimate2923">remain elevated</a> for thousands to tens of thousands of years. That’s because it takes a long time for carbon dioxide to move into soils, plants, the ocean and rocks. We are creating conditions conducive to a very long period of warmth, just like MIS 11.</p>
<p>Unless people dramatically lower the concentration of carbon dioxide in the atmosphere, evidence we found of Greenland’s past suggests a largely ice-free future for the island. </p>
<p>Everything we can do to reduce carbon emissions and <a href="https://theconversation.com/the-earth-needs-multiple-methods-for-removing-co2-from-the-air-to-avert-worst-of-climate-change-121479">sequester carbon</a> that is already in the atmosphere will increase the chances that more of Greenland’s ice survives.</p>
<p>The alternative is a world that could look a lot like MIS 11 – or even more extreme: a warm Earth, shrinking ice sheets, rising sea level, and waves rolling over Miami, Mumbai, India and Venice, Italy.</p><img src="https://counter.theconversation.com/content/209018/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Bierman receives funding from the US National Science Foundation.</span></em></p><p class="fine-print"><em><span>Tammy Rittenour receives funding from the US National Science Foundation.. </span></em></p>
The soil was extracted during the Cold War from beneath one of the U.S military’s most unusual bases, then forgotten for decades.
Paul Bierman, Fellow of the Gund Institute for Environment, Professor of Natural Resources and Environmental Science, University of Vermont
Tammy Rittenour, Professor of Geosciences and Director of Luminescence Lab, Utah State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/207468
2023-06-29T12:17:15Z
2023-06-29T12:17:15Z
Meltwater is infiltrating Greenland’s ice sheet through millions of hairline cracks – destabilizing its structure
<figure><img src="https://images.theconversation.com/files/534388/original/file-20230627-36062-evdjnn.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2500%2C1661&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Richard Bates and Alun Hubbard kayak a meltwater stream on Greenland's Petermann Glacier, towing an ice radar that reveals it's riddled with fractures.</span> <span class="attribution"><span class="source">Nick Cobbing.</span></span></figcaption></figure><p>I’m striding along the steep bank of a raging white-water torrent, and even though the canyon is only about the width of a highway, the river’s flow is greater than that of London’s Thames. The deafening roar and rumble of the cascading water is incredible – a humbling reminder of the raw power of nature.</p>
<p>As I round a corner, I am awestruck at a completely surreal sight: A gaping fissure has opened in the riverbed, and it is swallowing the water in a massive whirlpool, sending up huge spumes of spray. This might sound like a computer-generated scene from a blockbuster action movie – but it’s real.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/534120/original/file-20230626-19-t5ctl6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534120/original/file-20230626-19-t5ctl6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=336&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534120/original/file-20230626-19-t5ctl6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=336&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534120/original/file-20230626-19-t5ctl6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=336&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534120/original/file-20230626-19-t5ctl6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534120/original/file-20230626-19-t5ctl6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534120/original/file-20230626-19-t5ctl6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Alun Hubbard stands beside a moulin forming in a meltwater stream on the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Courtesy of Alun Hubbard</span></span>
</figcaption>
</figure>
<p>A moulin is forming right in front of me on the Greenland ice sheet. Only this really shouldn’t be happening here – current scientific understanding doesn’t accommodate this reality.</p>
<p>As a <a href="https://www.researchgate.net/profile/Alun-Hubbard">glaciologist</a>, I’ve spent 35 years investigating how meltwater affects the flow and stability of glaciers and ice sheets.</p>
<p>This gaping hole that’s opening up at the surface is merely the beginning of the meltwater’s journey through the guts of the ice sheet. As it funnels into moulins, it <a href="https://cires1.colorado.edu/science/spheres/snow-ice/images/iceMeltGraphic.jpg">bores a complex network of tunnels through the ice sheet</a> that extend many hundreds of meters down, all the way to the ice sheet bed. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/inTPFADBWt0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Scientists go into a moulin in this trailer for Into the Ice.</span></figcaption>
</figure>
<p>When it reaches the bed, the meltwater decants into the ice sheet’s subglacial drainage system – much like an urban stormwater network, though one that is constantly evolving and backing up. It carries the meltwater to the ice margins and ultimately ends up in the ocean, with major consequences for the thermodynamics and flow of the overlying ice sheet.</p>
<p>Scenes like this and <a href="https://doi.org/10.1038/s41561-023-01208-0">new research</a> into the ice sheet’s mechanics are challenging traditional thinking about what happens inside and under ice sheets, where observations are extremely challenging yet have stark implications. They suggest that Earth’s remaining ice sheets in Greenland and Antarctica are far more vulnerable to climate warming than models predict, and that the <a href="https://doi.org/10.1038/s41561-023-01208-0">ice sheets may be destabilizing from inside</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/stm1pBp0rfk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">NASA’s GRACE satellites capture Greenland’s ice loss from 2002-2021.</span></figcaption>
</figure>
<p>This is a tragedy in the making for the <a href="https://doi.org/10.1038/s41467-021-23810-9">half a billion people</a> who populate vulnerable coastal regions, since the Greenland and Antarctic ice sheets are effectively giant frozen freshwater reservoirs locking up <a href="https://nsidc.org/learn/parts-cryosphere/ice-sheets/ice-sheet-quick-facts">in excess of 65 meters</a> (over 200 feet) of equivalent global sea level rise. Since the 1990s their mass loss has been accelerating, becoming both the primary contributor to and the wild card in future sea level rise.</p>
<h2>How narrow cracks become gaping maws in ice</h2>
<p>Moulins are near-vertical conduits that capture and funnel the meltwater runoff from the ice surface each summer. There are many thousands across Greenland, and they can grow to impressive sizes because of the thickness of the ice coupled with the exceptionally high surface melt rates experienced. These gaping chasms can be as large as tennis courts at the surface, with chambers hidden in the ice beneath that could swallow cathedrals.</p>
<p>But this new moulin I’ve witnessed is really far from any crevasse fields and melt lakes, where current scientific understanding dictates that they should form.</p>
<figure class="align-center ">
<img alt="A helicopter sitting on the ice sheet looks tiny next to the gaping moulin, where a meltwater stream pours into the ice sheet." src="https://images.theconversation.com/files/534491/original/file-20230628-29982-adjj2j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534491/original/file-20230628-29982-adjj2j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534491/original/file-20230628-29982-adjj2j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534491/original/file-20230628-29982-adjj2j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534491/original/file-20230628-29982-adjj2j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534491/original/file-20230628-29982-adjj2j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534491/original/file-20230628-29982-adjj2j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">High rates of meltwater discharge combined with a thick and gently sloping ice sheet in Western Greenland gives rise to monster holes like this moulin.</span>
<span class="attribution"><span class="source">Alun Hubbard</span></span>
</figcaption>
</figure>
<p>In a <a href="https://doi.org/10.1038/s41561-023-01208-0">new paper</a>, <a href="https://scholar.google.co.uk/citations?hl=en&user=TVrXvoEAAAAJ&view_op=list_works&sortby=pubdate">Dave Chandler</a> and I demonstrate that ice sheets are littered with millions of tiny hairline cracks that are forced open by the meltwater from the rivers and streams that intercept them.</p>
<p>Because glacier ice is so brittle at the surface, such cracks are ubiquitous across the melt zones of all glaciers, ice sheets and ice shelves. Yet because they are so tiny, they can’t be detected by satellite remote sensing.</p>
<p>Under most conditions, we find that stream-fed hydrofracture like this allows water to penetrate hundreds of meters down before freezing closed, without the crack’s necessarily penetrating to the bed to form a full-fledged moulin. But, even these partial-depth hydrofractures have considerable impact on ice sheet stability.</p>
<p>As the water pours in, it damages the ice sheet structure and releases its latent heat. The ice fabric warms and softens and, hence, flows and melts faster, just like warmed-up candle wax.</p>
<figure class="align-center ">
<img alt="Alun Hubbard using a rappelling rope lowers himself from the top of the ice sheet into a huge hold with water pouring down the sides. The hole appears to be as wide as a two-lane road." src="https://images.theconversation.com/files/534492/original/file-20230628-28043-kaqy3c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534492/original/file-20230628-28043-kaqy3c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534492/original/file-20230628-28043-kaqy3c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534492/original/file-20230628-28043-kaqy3c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534492/original/file-20230628-28043-kaqy3c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534492/original/file-20230628-28043-kaqy3c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534492/original/file-20230628-28043-kaqy3c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Alun Hubbard rappels into a moulin in October 2019, a point in the year when surface melt should have ceased but hadn’t.</span>
<span class="attribution"><span class="source">Lars Ostenfeld / Into the Ice</span></span>
</figcaption>
</figure>
<p>The stream-driven hydrofractures mechanically damage the ice and transfer heat into the guts of the ice sheet, destabilizing it from the inside. Ultimately, the internal fabric and structural integrity of ice sheets is becoming more vulnerable to climate warming.</p>
<h2>Emerging processes that speed up ice loss</h2>
<p>Over the past two decades that scientists have tracked ice sheet melt and flow in earnest, melt events have become <a href="https://www.esa.int/Applications/Observing_the_Earth/FutureEO/CryoSat/Meltwater_runoff_from_Greenland_becoming_more_erratic">more common and more intense</a> as <a href="https://climate.nasa.gov/vital-signs/global-temperature/">global temperatures rise</a> – further exacerbated by <a href="https://www.nature.com/articles/s43247-022-00498-3">Arctic warming of almost four times the global mean</a>.</p>
<p>The ice sheet is also flowing and calving icebergs much faster. It has lost about <a href="https://climate.nasa.gov/vital-signs/ice-sheets/">270 billion metric tons of ice per year</a> since 2002: over a centimeter and a half (half an inch) of global sea-level rise. Greenland is now, on average, contributing around 1 millimeter (0.04 inches) to the sea level budget annually.</p>
<p>A 2022 study found that even if atmospheric warming stopped now, <a href="https://doi.org/10.1038/s41558-022-01441-2">at least 27 centimeters – nearly 1 foot – of sea level rise</a> is inevitable because of Greenland’s imbalance with its past two decades of climate.</p>
<p>Understanding the risks ahead is crucial. However, the current generation of ice sheet models used to assess how Greenland and Antarctica will respond to warming in the future don’t account for amplification processes that are being discovered. That means the models’ sea-level rise estimates, used to inform Intergovernmental Panel on Climate Change (IPCC) reports and policymakers worldwide, are conservative and lowballing the rates of global sea rise in a warming world.</p>
<figure class="align-center ">
<img alt="Two people stand inside an ice cave with light coming from a large hole above." src="https://images.theconversation.com/files/534490/original/file-20230628-25-453mgb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534490/original/file-20230628-25-453mgb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=899&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534490/original/file-20230628-25-453mgb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=899&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534490/original/file-20230628-25-453mgb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=899&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534490/original/file-20230628-25-453mgb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534490/original/file-20230628-25-453mgb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534490/original/file-20230628-25-453mgb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Daniela Barbieri and Alun Hubbard explore the contorted englacial plumbing deep inside a Greenland moulin.</span>
<span class="attribution"><span class="source">Lars Ostenfeld / Into the Ice</span></span>
</figcaption>
</figure>
<p>Our new finding is just the latest. Recent studies have shown that:</p>
<ul>
<li><p>Warming ocean currents are intruding into the <a href="https://doi.org/10.1038/s41598-019-53190-6">Antarctic</a> and <a href="https://doi.org/10.1038/ngeo316">Greenland</a> coastlines, flowing under the <a href="https://doi.org/10.1126/science.aaa0940">ice shelves</a> to undercut outlet glaciers and <a href="https://doi.org/10.5194/tc-8-1457-2014">destabilize their calving fronts</a>.</p></li>
<li><p>Increasing rainfall across the Greenland ice sheet not only depletes snow accumulation, it also <a href="https://doi.org/10.1038/ngeo2482">accelerates surface melting and ice flow</a>.</p></li>
<li><p><a href="https://doi.org/10.3389/feart.2015.00078">Algae and microbes</a>, along with <a href="https://doi.org/10.1126/sciadv.aav3738">surface snowpack melt</a>, darken the ice sheet surface, absorbing more solar radiation, which <a href="https://doi.org/10.5194/tc-14-309-2020">also accelerates ice melt</a>.</p></li>
<li><p><a href="https://doi.org/10.5194/tc-10-1147-2016">Superimposed ice slabs within the snowpack</a> are forming across the accumulation zone, forming an impermeable barrier that depletes meltwater retention and drives extraordinary runoff.</p></li>
<li><p>Water at the base of the ice sheet thaws and <a href="https://doi.org/10.1029/2010GL044397">softens the frozen bed, thereby triggering basal sliding</a> and <a href="https://doi.org/10.1002/2013GL058933">accelerating interior ice sheet flow</a> to the margins.</p></li>
</ul>
<p>In the last months, other papers also described previously unknown feedback processes underway beneath ice sheets that computer models currently can’t include. Often these processes happen at too fine a scale for models to pick up, or the model’s simplistic physics means the processes themselves can’t be captured.</p>
<p>Two such studies independently identify <a href="https://doi.org/10.1073/pnas.2220924120">enhanced submarine melting at the grounding line in Greenland</a> and <a href="https://doi.org/10.1038/s41586-022-05691-0">Antarctica</a>, where large outlet glaciers and ice streams drain into the sea and start to lift off their beds as floating ice shelves. These processes greatly accelerate ice sheet response to climate change and, in the case of Greenland, could potentially double future mass loss and its <a href="https://doi.org/10.1073/pnas.2220924120">contribution to rising sea level</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/534131/original/file-20230626-25-ynneln.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534131/original/file-20230626-25-ynneln.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=383&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534131/original/file-20230626-25-ynneln.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=383&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534131/original/file-20230626-25-ynneln.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=383&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534131/original/file-20230626-25-ynneln.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=481&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534131/original/file-20230626-25-ynneln.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=481&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534131/original/file-20230626-25-ynneln.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=481&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Greenland’s ice loss through meltwater and calving of glaciers has contributed nearly 10 centimeters (4 inches) to global sea-level rise since 1900. The chart shows sea level rise from all sources through 2018.</span>
<span class="attribution"><a class="source" href="https://climate.nasa.gov/vital-signs/sea-level/">NASA’s Goddard Space Flight Center/PO.DAAC</a></span>
</figcaption>
</figure>
<h2>Current climate models lowball the risks</h2>
<p>Along with other <a href="https://doi.org/10.1016/j.oneear.2020.11.002">applied glaciologists</a>, “<a href="https://www.pnas.org/doi/full/10.1073/pnas.1817205116">structured expert judgment</a>” and a <a href="https://doi.org/10.5194/tc-15-5705-2021">few candid modelers</a>, I contend that the current generation of ice sheet models used to inform the IPCC are not capturing the abrupt changes being observed in Greenland and Antarctica, or the risks that lie ahead.</p>
<p>Ice sheet models don’t include these emerging feedbacks and respond over millennia to strong-warming perturbations, leading to sluggish sea level forecasts that are lulling policymakers into a false sense of security. We’ve come a long way since the first IPCC reports in the early 1990s, which treated polar ice sheets as completely static entities, but we’re still short of capturing reality.</p>
<p>As a committed field scientist, I am keenly aware of how privileged I am to work in these sublime environments, where what I observe inspires and humbles. But it also fills me with foreboding for our low-lying coastal regions and what’s ahead for the <a href="https://doi.org/10.3389/fenvs.2021.751978">10% or so of the world’s population</a> that lives in them.</p><img src="https://counter.theconversation.com/content/207468/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alun Hubbard acknowledges funding from the Research Council of Norway (Centers of Excellence: CAGE & iC3), The Academy of Finland (PROFI4: Arctic Interactions) and is additionally affiliated to Oulun Yliopisto (Oulu University), Arctic Basecamp and La Venta Esplorazioni Geografiche.</span></em></p>
Glaciologists are discovering new ways surface meltwater alters the internal structure of ice sheets, and raising an alarm that sea level rise could be much more abrupt than current models forecast.
Alun Hubbard, Professor of Glaciology, Fulbright Scholar, University of Tromsø
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/207355
2023-06-28T15:12:36Z
2023-06-28T15:12:36Z
From raising the global sea level to crushing life on the seafloor – here’s why you should care about icebergs
<figure><img src="https://images.theconversation.com/files/534283/original/file-20230627-23-8yvpno.jpg?ixlib=rb-1.1.0&rect=26%2C13%2C4375%2C2923&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Icebergs in Disko Bay, western Greenland.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/icebergs-disco-bay-near-ilulissat-greenland-1888385068">Chris Christophersen/Shutterstock</a></span></figcaption></figure><p>Late in the evening of April 14 1912, the <a href="https://theconversation.com/titanic-twist-1912-wasnt-a-bad-year-for-icebergs-after-all-25621">RMS Titanic collided with an iceberg</a> in the north-west Atlantic. In just over two and a half hours, the Titanic sank, claiming the lives of 1,514 people.</p>
<p>The Titanic disaster is one good reason to understand icebergs better. But their significance extends far beyond posing a risk to ships and other offshore structures. Icebergs are crucial to monitor because of their profound impact on the natural world and human societies.</p>
<p>Icebergs are formed when chunks of ice break off from the front of glaciers and floating ice shelves. They exist in a range of sizes, from small formations known as “growlers” and “bergy bits” (that extend up to 5 metres above sea level), to larger icebergs aptly referred to as “giants”. </p>
<p>In 2000, one of Antarctica’s largest icebergs, <a href="https://earthobservatory.nasa.gov/images/552/iceberg-b-15-ross-ice-shelf-antarctica">called B-15</a>, had a surface area roughly the same size as Jamaica. Since then, <a href="https://earthobservatory.nasa.gov/images/92238/end-of-the-journey-for-iceberg-b-15z">B-15 has fractured</a> into a number of smaller pieces and most have melted away. </p>
<p>Icebergs that break off from an already floating ice shelf do not displace ocean water when they melt, just as melting ice cubes do not raise the liquid level in a glass. But when an ice shelf collapses, it no longer holds back inland glacial ice. This inland ice will then move faster and can rapidly release new icebergs, which displace ocean water and contribute to sea level rise. </p>
<p>In 2022, Antarctica’s <a href="https://theconversation.com/conger-ice-shelf-has-collapsed-what-you-need-to-know-according-to-experts-180077">Conger ice shelf</a> collapsed. Some of the continent’s other large <a href="https://www.antarcticglaciers.org/glaciers-and-climate/changing-antarctica/shrinking-ice-shelves/ice-shelves/">ice shelves</a> are also thought to be at risk of collapse in the future, particularly those around the unstable West Antarctic ice sheet. The collapse of the West Antarctic ice sheet alone could <a href="https://www.antarcticglaciers.org/question/ice-antarctica-melt-much-global-sea-level-rise-quickly-likely-happen/">raise the global sea level by 3.2 metres</a>. </p>
<figure class="align-center ">
<img alt="A glacier calving large chunks of ice into the ocean." src="https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A chunk of ice breaking off from a glacier in Neko Harbour, Antarctica.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/neko-harbor-glacier-calving-andvord-bay-1556725400">Steve Allen/Shutterstock</a></span>
</figcaption>
</figure>
<p>Global warming accelerates not only iceberg release, but also the rate at which icebergs melt. As icebergs melt, they release freshwater to the ocean. </p>
<p>In the northern hemisphere, a surplus of freshwater from the Greenland ice sheet in the future has the potential to weaken or even shut down the North Atlantic Conveyor “pump”, which circulates warm tropical waters northwards. If the North Atlantic Conveyor pump is significantly affected, the northern hemisphere could be plunged into <a href="https://www.tandfonline.com/doi/abs/10.1080/00167487.2005.12094137">sub-zero, glacial conditions</a>. </p>
<h2>‘Scouring’ the seabed</h2>
<p>Icebergs are often thought of as floating masses of ice. Yet their undersides regularly come into contact with the seabed, gouging out sediment on the seafloor to form “scour” marks. Some <a href="https://www.int-res.com/abstracts/meps/v186/p1-8/">15–20% of the world’s oceans</a> are affected by this phenomenon.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0277379116303638">Research</a> that I co-authored in 2016 on iceberg scouring in East Greenland, found that icebergs can disturb sediment up to several metres below the seabed. This disturbance poses a risk to offshore marine structures such as buried pipelines and telecommunication cables.</p>
<p>Icebergs can also crush plants and animals when they collide with the seabed. These organisms, such as seagrasses and molluscs, are important stores of carbon in polar regions. In areas of West Antarctica, referred to as <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.13523">“iceberg killing fields”</a>, iceberg scouring may recycle around 80,000 tonnes of carbon back into the atmosphere each year. </p>
<h2>Ocean fertilisers (and polluters)</h2>
<p>But it’s not all bad news. Some icebergs contain substantial amounts of iron-rich sediment, known as “dirty ice”. These icebergs <a href="https://www.nature.com/articles/s41467-019-13231-0">fertilise the ocean</a> by supplying important nutrients to marine organisms such as phytoplankton. </p>
<p>Following the passage of an iceberg, there is an increase in organism growth and levels of chlorophyll (the green pigment in plants used for photosynthesis) in the surrounding water. This can result in vibrant blooms that extract CO₂ from the atmosphere as they grow. </p>
<p><a href="https://www.nature.com/articles/ngeo2633">One study</a> on icebergs in the Southern Ocean found that these blooms can be up to ten times the length of the iceberg and can persist for more than a month. Blooms in the wake of icebergs off Antarctica have the capacity to absorb <a href="https://www.cbc.ca/news/science/icebergs-climate-change-1.3401729#:%7E:text=Ocean%20blooms%20in%20the%20wake,as%20Sweden%20or%20New%20Zealand.">up to 40 million tonnes of carbon</a> each year.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A satellite image of a phytoplankton bloom in the Ross Sea, Southern Ocean." src="https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">January 22, 2011: a phytoplankton bloom in the Ross Sea, Southern Ocean.</span>
<span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/images/48949/bloom-in-the-ross-sea">Norman Kuring/NASA Goddard Space Flight Center</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>But icebergs hold more than just nutrients in their icy structures. Glacier ice may harbour <a href="https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-021-01106-w">ancient bacterial and viral microbes</a>, even including <a href="https://www.tandfonline.com/doi/full/10.1657/1938-4246-44.4.432">buried faecal microorganisms</a>. These microbes will eventually emerge at the glacier’s surface or in icebergs where they will enter natural ecosystems and could pose a threat to human health. </p>
<p><a href="https://journals.sagepub.com/doi/pdf/10.1177/03091333221107376">Research</a> has also identified various other contaminants within glaciers. These include soot, nuclear fallout, potentially toxic elements such as arsenic, mercury and lead, nitrogen-based contaminants such as fertilisers and animal waste, microplastics and persistent organic pollutants such as pesticides and solvents. </p>
<p>Scientists are, however, exploring the possibility of <a href="https://www.nature.com/articles/s41598-022-26952-y#:%7E:text=A%20long%2Dheld%20idea%20is,United%20Arab%20Emirates%20(UAE)">towing icebergs to water-scarce regions</a>. An iceberg holding 20 billion gallons of freshwater could potentially <a href="https://www.theguardian.com/environment/2017/may/05/could-towing-icebergs-to-hot-places-solve-the-worlds-water-shortage">meet the water needs of a million people</a> for five years – provided that the water is uncontaminated. </p>
<p>Icebergs have an impact on our oceans, atmosphere and societies. As the climate emergency intensifies and our glaciers and ice sheets continue to recede, the significance of icebergs will only grow, for better or worse.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 20,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/207355/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lorna Linch does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Icebergs don’t just pose a risk to ships – they have a profound impact on the natural world and human societies.
Lorna Linch, Principal Lecturer in Physical Geography, University of Brighton
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/207785
2023-06-23T15:51:06Z
2023-06-23T15:51:06Z
The melting Arctic is a crime scene. The microbes I study have long warned us of this catastrophe – but they are also driving it
<p>The Arctic’s climate is warming at least four times faster than the global average, causing irrevocable changes to this vast <a href="https://news.sky.com/story/dramatic-changes-to-polar-ice-caps-revealed-on-new-map-of-arctic-and-antarctica-12898550">landscape</a> and precarious <a href="https://www.nwf.org/Educational-Resources/Wildlife-Guide/Wild-Places/Arctic#:%7E:text=The%20Arctic%20is%20a%20unique,in%20the%20summer%20to%20breed.">ecosystem</a> – from the anticipated <a href="https://earth.org/polar-bears-to-become-extinct-by-2100/">extinction of polar bears</a> to the <a href="https://www.scientificamerican.com/article/as-arctic-sea-ice-melts-killer-whales-are-moving-in/#:%7E:text=Killer%20whales%20often%20feed%20on,navigate%20through%20the%20icy%20waters.">appearance of killer whales</a> in ever-greater numbers. A new <a href="https://www.nature.com/articles/s41467-023-38511-8">study</a> suggests the Arctic Ocean could be ice-free in summer <a href="https://theconversation.com/arctic-ocean-could-be-ice-free-in-summer-by-2030s-say-scientists-this-would-have-global-damaging-and-dangerous-consequences-206974">as soon as the 2030s</a> – around a decade earlier than previously predicted.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of Arctic sea ice changes" src="https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=700&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=700&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=700&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=879&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=879&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=879&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A new Arctic sea ice map compares the 30-year average with recent ten-year averages.</span>
<span class="attribution"><a class="source" href="https://www.bas.ac.uk/media-post/new-map-of-polar-regions-updated-to-reflect-ice-loss-name-changes-and-new-data/">British Antarctic Survey</a></span>
</figcaption>
</figure>
<p>But to properly understand the pace and force of what’s to come, we should instead focus on organisms too small to be seen with the naked eye. These single-celled microbes are both the watchkeepers and arch-agitators of the Arctic’s demise.</p>
<p>Scientists like me who study them have become forensic pathologists, processing crime scenes in our Arctic field sites. We don the same white anti-contamination suits, photograph each sampling site, and bag our samples for DNA analysis. In some areas, red-coloured microbes even create an effect known as “blood snow”.</p>
<p>In this complex criminal investigation, however, the invisible witnesses are also responsible for the damage being done. Microbes testify to the vulnerability of their Arctic habitats to the changes that humans have caused. But they also create powerful climate feedback loops that are doing ever-more damage both to the Arctic, and the planet as a whole.</p>
<h2>Zipping headlong into icy oblivion</h2>
<p>My first visit to the Arctic was also nearly my last. As a PhD student in my early 20s in 2006, I had set out with colleagues to sample microbes growing on a glacier in the Norwegian archipelago of <a href="https://www.theguardian.com/environment/2023/may/13/svalbard-the-arctic-islands-where-we-can-see-the-future-of-global-heating">Svalbard</a> – the planet’s northernmost year-round settlement, about 760 miles from the North Pole.</p>
<p>Our treacherous commute took us high above the glacier, traversing an icy scree slope to approach its flank before crossing a river at the ice’s margin. It was a route we had navigated recently – yet this day I mis-stepped. Time slowed as I slid towards the stream swollen with ice melt, my axe bouncing uselessly off the glassy ice. I was zipping headlong into icy oblivion.</p>
<p>In that near-death calm, two things bothered me. The water would carry me deep into the glacier, so it would be decades before my remains were returned to my family. And the ear-worm of that field season meant I would die to the theme tune to Indiana Jones.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>This article is part of Conversation Insights</em></strong>
<br><em>The Insights team generates <a href="https://theconversation.com/uk/topics/insights-series-71218">long-form journalism</a> derived from interdisciplinary research. The team is working with academics from different backgrounds who have been engaged in projects aimed at tackling societal and scientific challenges.</em></p>
<hr>
<p>Thankfully, the scree slowed my slide – I lived and learned, quickly, that dead scientists don’t get to write up their papers. And I’m still learning about the tiny organisms that populate every habitat there: from seawater in the Arctic Ocean to ice crystals buried deep in the <a href="https://en.wikipedia.org/wiki/Greenland_ice_sheet">Greenland ice sheet</a>.</p>
<p>These micro-managers of all manner of planetary processes are acutely sensitive to the temperatures of their habitats. The slightest change above freezing can transform an Arctic landscape from a frozen waste devoid of liquid water to one where microbes get busy reproducing in nutrient-rich water, transforming themselves in ways that <a href="https://www.nature.com/articles/ismej2010108">further amplify</a> the effects of climate warming.</p>
<p>The Svalbard region is now warming seven times faster than the global average. While much of the world continues its efforts to limit global warming to 1.5°C above pre-industrial levels, in the Arctic, that battle was lost long ago.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0VOGGdeB8eI?wmode=transparent&start=17" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Joseph Cook’s film on the microbes that inhabit the Greenland ice sheet.</span></figcaption>
</figure>
<h2>Decades ahead of us all</h2>
<p>It’s 2011, and <a href="http://www.earth.s.chiba-u.ac.jp/english/education/education02/staff16.html">Nozomu Takeuchi</a> is visiting Svalbard from Japan. It has been a difficult year back home, following the earthquake, tsunami and Fukushima nuclear incident, but Nozomu – a glacier ecologist and professor at Chiba University – is unrelenting in his quest to measure the effects of climate change. </p>
<p>Just hours after he stepped off a plane in the August midnight sun at Longyearbyen airport, we are marching up the nearest glacier. Above us, snow-capped mountain sides loom out of the swirling mist.</p>
<p>Since the 1990s, Nozomu has been collecting samples and measurements from glaciers all over the world. When we reach our goal near the snowline, he opens his rucksack to reveal a bento box full of sampling kit – stainless steel scoops, test tubes, sample bags, all arranged for efficiency. As he scurries around with practised efficiency, I think of offering help but fear I would only slow him down.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist takes a reading in snowy Arctic landscape" src="https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nozomu Takeuchi measuring the biological darkening of a Svalbard glacier in 2011.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In truth, Nozomu is decades ahead of us all. Years ago, he made the link between the future of life and the death of ice, and these melting Svalbard glaciers are adding yet more points to his graphs.</p>
<p>Just as we apply oodles of factor 50 to protect ourselves from the Sun, so the billions of microbes sandwiched between the sky and surface of the glacier protect themselves by accumulating sunscreen-like pigments. And if enough of these pigments rest in one place under the Sun, this area of “biological darkening” absorbs the heat of the Sun much more effectively than reflective white snow and ice – so it melts faster.</p>
<p>Nozomu scoops up some of the so-called blood snow, heavily laden with algae. Under the microscope, their cells are indeed reminiscent of red blood cells. But rather than haemoglobin, these cells are laden with carotenoids – pigments also found in vegetables that <a href="https://academic.oup.com/femsec/article/94/3/fiy007/4810544?login=false">protect the algae from overheating</a>. Other patches of the glacier are verdant green, rich in algae that are busy photosynthesising light into chemical energy in this 24-hour daylight world.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man in icy landscape holding scientific sample" src="https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author with a sample of ‘blood snow’, collected from a glacier surface.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Further down the glacier, the professor crushes some “dirty” ice into a bag. A different kind of algae lives here that, depending on your point-of-view, is either black, brown or purple (perhaps it depends on the tint of your sunglasses). The <a href="https://www.researchgate.net/figure/Chemical-structure-of-compound-3-purpurogallin-carboxylic-acid-6-O-b-d-glucopyranoside_fig2_51806131#:%7E:text=A%20gallotannin%20derivative%20(galloylglucopyranose%2C%20i.e.,et%20al.%2C%202012b)%20.">pigment</a> created is like the compounds that colour tea, and the algae keep it in layers like parasols above the photosynthetic factories within their cells – ensuring they have just enough sunlight to photosynthesise, but not enough to burn.</p>
<p>Open Google Earth and as you zoom in on the Arctic, you may spot the large dark stripe that scars the western margin of the <a href="https://en.wikipedia.org/wiki/Greenland_ice_sheet">Greenland ice sheet</a>. This is the “dark zone”, but it’s not caused by dark <a href="https://www.nature.com/articles/s41467-020-20627-w">dust</a> or soot. It’s alive, <a href="https://www.nature.com/articles/ismej2012107">laden with algae</a> – and it has been darkening, and growing, as Greenland warms.</p>
<p>Between 2000 and 2014, the <a href="https://www.frontiersin.org/articles/10.3389/feart.2016.00043/full">dark zone’s area grew by 14%</a>. At 279,075 km² in 2012, it was already more than twice the <a href="https://www.britannica.com/summary/England#:%7E:text=Area%3A%2050%2C301%20sq%20mi%20(130%2C278,even%20with%20the%20entire%20kingdom.).%20This%20had%20a%20powerful%20impact%20on%20the%20rate%20of%20ice%20melt%20--%20areas%20blooming%20with%20algae%20%5Bmelt%20nearly%202cm%20more%20each%20day%5D(https://www.pnas.org/doi/abs/10.1073/pnas.1918412117">size of England</a> than bare ice.</p>
<p>Next morning, I am woken by the smell of chemicals, having slept beneath a coffee table. Nozomu is busy processing his samples: bags of melting ice pinned to a clothesline by bulldog clips. They resemble bunting around the crowded room, but this is no time for celebration. The tint of each bag adds a measurement which quantifies the link between these algae, their pigments, and the death of their icy home.</p>
<h2>The case becomes urgent</h2>
<p>By the summer of 2014, glaciologists all over the world have started to listen to the warnings of pioneering ecologists such as Nozomu. The glaciers are dying even as life blossoms on their darkening surfaces. The case has become urgent.</p>
<p>I am in a helicopter, flying with colleagues to a camp in the dark zone on the Greenland ice sheet – the largest mass of glacial ice in the northern hemisphere. Covering 1.7 million km², its ice holds the equivalent of the water required to raise global sea levels by 7.7 metres.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A landscape of dark ice intertwined with blue rivers of meltwater." src="https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A highly darkened surface of the Greenland ice sheet, rich in algae and incised with rivers of meltwater.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>As we warm our climate, the rate of water flowing from this reservoir increases, with each degree Celsius added to global temperatures opening the drainage valve even wider. Feedback processes such as biological darkening have the potential to multiply the number of drainage valves that are open, hastening dramatically the rate at which sea levels rise.</p>
<p>To monitor this effect, every day <a href="https://www.gla.ac.uk/schools/ges/staff/karencameron/">Karen Cameron</a>, the leader of our camp this summer, walks to undisturbed patches of ice carrying a £100,000 backpack which contains a spectrometer to measure the darkness of the ice, capturing how it absorbs the solar energy that causes melting. The glaciologists are desperate for ground truth, and their models need data.</p>
<p>Up to this point, none of their predictions of how the Greenland ice sheet would respond to our warming climate have included biological darkening. Even if the effect were modest, it could still topple the ice sheet from a predictable, straightline response to climate warming.</p>
<p>All the time we are in Greenland, the only lifeforms we encounter are the flies that hatch from the fresh fruit and peppers in our food rations. These and the few types of glacier algae and several hundred kinds of bacteria that are biologically darkening the ice: a living scum scarring the surface of the ice sheet.</p>
<p>My work focuses on how these tiny organisms adapt to their icy habitat, but the implications of their behaviour are now of global concern. A <a href="https://screenworks.org.uk/archive/baftss-practice-research-award-2017/timeline">filmmaker</a> at the camp is weaving a thread between the ice melt in Greenland and its consequences for people living in coastal communities all over the world – from villages near my home on the <a href="https://www.theguardian.com/environment/2019/may/18/this-is-a-wake-up-call-the-villagers-who-could-be-britains-first-climate-refugees">west coast of Wales</a>, to huge metropolises like Manhattan, Amsterdam and Mumbai, and even entire low-lying island nations in the Pacific.</p>
<p>As smaller glaciers fade, and the larger ice sheets of Greenland and Antarctica start to respond with full force to our warming climate, it is these communities, capitals and countries that will bear the brunt of the flooding, inundation and erosion that comes with rising sea levels.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two scientists inspecting an ice corer device dripping with meltwater." src="https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author (left) and Joseph Cook high on the Greenland ice sheet, meltwater dripping from their ice corer.</span>
<span class="attribution"><span class="source">Sara Penrhyn Jones</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Before heading home, our helicopter takes us on a detour, high over the ice sheet. We fly over the brown-black-purple algae to brighter, higher elevations where the palette shrinks to the blue and white of water and ice, then snow and sky. Greenland makes its own weather and, in these higher elevations, we expect the ice to be frozen all year round. When we land and begin to collect snow samples and a small ice core, however, we find we are digging into slush. The ice has started to melt up here, too. </p>
<p>We heave up our ice corer, and meltwater dribbles out from its bottom. In periods of extreme warming, much of the surface of the ice sheet can experience melting episodes, <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2015.00225/full">disturbing the slumbering microbes</a> stored within the otherwise permanently frozen surface. It’s a sobering moment for us all.</p>
<p>Flying back to camp, I watch the streams become rivers and lakes as we head back over the dark zone, where melt and microbes dominate the icescape. I contemplate how much water, once locked in the ice, will become free to flow into the sea and into millions of homes by the end of the century.</p>
<h2>Popping a pingo</h2>
<p>The frozen lands of eight nations encircle the Arctic. Their soils store vast quantities of carbon: a third of the planet’s entire quantity of soil carbon resides in this frozen ground.</p>
<p>The carbon is a legacy of soils formed in past climates and preserved for millennia. However, human-induced climate change is reheating this leftover carbon, providing a luxuriant food source for microbes resident within the <a href="https://earthobservatory.nasa.gov/biome/biotundra.php">tundra</a>, which then emit it as greenhouse gases.</p>
<p>This is known as the <a href="https://en.wikipedia.org/wiki/Permafrost_carbon_cycle#:%7E:text=Carbon%20emissions%20from%20permafrost%20thaw,which%20increases%20permafrost%20thaw%20depths.">permafrost carbon</a> feedback loop. When even modest quantities of this vast carbon store reach the atmosphere, warming accelerates – resulting in faster thawing of the tundra and the release of yet more greenhouse gases.</p>
<p>Furthermore, not all greenhouse gases are equal in their impact. While carbon dioxide is relatively abundant and stable for centuries in the atmosphere, methane is less abundant and shorter-lived, but remarkably powerful as a greenhouse gas – nearly 30 times more damaging to the climate than carbon dioxide, for the same volume.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist crouched on ice taking water samples." src="https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=307&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=307&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=307&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=386&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=386&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=386&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Andy Hodson sampling methane from a freshly ‘popped’ pingo.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>For more than three decades, <a href="https://www.unis.no/staff/andy-hodson/">Andy Hodson</a> has worked at the frontier where microbes, carbon and the Arctic landscape meet. In 2018, we join him on a brisk spring day in Svalbard. It’s -26°C but the snowmobile commute is thankfully brief – then we work quickly against the cold.</p>
<p>Hodson’s plan is to “pop” one of the many <a href="https://en.wikipedia.org/wiki/Pingo">pingos</a> that populate the floor of this wide open valley. Think of pingos as the acne of the Arctic: they form as permafrost compresses unfrozen wet sediments, erupting as small hills blistering the skin of the tundra.</p>
<p>The story of these microbes’ lives is complicated. They only live beyond the reach of oxygen – where oxygen is more prevalent, methane-consuming microbes thrive instead, quenching the belches of methane from below. Similarly, should mineral sources of iron or sulphide be nearby, then microbes that use them outcompete the methanogens.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small fountain of water in an opening in the ice, amid a snowy landscape." src="https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A popped pingo discharging supercooled water rich in methane.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>It all adds up to one of the greatest uncertainties for our civilisation: the extent and composition of greenhouse gases escaping from Arctic lands. <a href="https://www.cam.ac.uk/research/news/emissions-from-melting-permafrost-could-cost-43-trillion#:%7E:text=Increased%20greenhouse%20gas%20emissions%20from,and%20the%20University%20of%20Colorado.">Estimates of the economic impacts</a> from this permafrost carbon feedback tally in the tens of trillions of dollars to the global economy. We know it is bad news, but exactly how bad depends on the microbes in their microscopic mosaic.</p>
<p>Hodson’s field work shows that, during the Arctic winter, this pingo is probably the only source of methane in the immediate area, its chimney enabling the gas to escape from the depths of the ice before methane-consuming microbes can catch it. Annually, tens of kilograms of methane and more than a ton of carbon dioxide will escape from this pingo alone - one of <a href="https://doi.org/10.1016/j.geomorph.2023.108694">more than 10,000</a> scattered across the Arctic, in addition to its other methane-producing hotspots.</p>
<h2>A near-perfect ecosystem</h2>
<p>Arctic lands are a patchwork of permafrost carbon feedbacks, and our future depends on the uncertain fate of the microbes within. </p>
<p>While the ice melt enhances the growth of microbes in the short term, if it continues to the point of erasing habitats then the microbes will be lost with them. We recognise this danger for polar bears and walruses, but not the invisible biodiversity of the Arctic. Small does not mean insignificant though.</p>
<p>To appreciate this, we can head back to the dark zone on Greenland’s ice sheet and join <a href="https://www.rolex.org/rolex-awards/exploration/joseph-cook">Joseph Cook</a> during our summer 2014 field season. He’s lying on a mat improvised from a bath towel and a binbag wrapped in duct tape, peering into a dark, pothole-like depression in the ice. It’s a cryoconite hole, and millions of them are dotted over the edges of the ice sheet. Where pingos contribute to climate warming by emitting methane, cryoconite is a good sink of greenhouse gases, but this creates its own problems. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Crouching scientist takes samples in the Arctic snow." src="https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Joseph Cook measuring the carbon cycling activities of Greenland’s cryoconite holes.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2008.01758.x">earliest estimate</a> of its ability to store carbon dioxide from the air on the ice surface of the world’s glaciers exceeded Finland’s total carbon emissions in the same year. Every cryoconite hole is a near-perfect ecosystem – with a singular flaw. Its inhabitants must melt ice to live. But the very act of melting the ice hastens the demise of their glacier habitat. </p>
<p>Despite being found in some of the harshest locations on Earth, cryoconite is home for thousands of different types of bacteria (including the all-important photosynthetic cyanobacteria), fungi, and <a href="https://microbiologysociety.org/why-microbiology-matters/what-is-microbiology/protozoa.html">protozoa</a>. Even <a href="https://www.theguardian.com/environment/2020/oct/17/tardigrade-ice-hole-arctic-greenland">tardigrades</a> thrive in cryoconite.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscope image of a single cryoconite granule." src="https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microscope image of a cryoconite granule, showing biological darkening and cyanobacteria growing through it.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Cook is professionally besotted with the perfection of this near-frozen “microscopic rainforest”. Its inhabitants are shielded and nourished at just the right depth and in the right shape for a busy ecosystem to be engineered by the interaction of sunlight with cyanobacteria, dust and ice to the benefit of all its inhabitants. The cyanobacteria use sunshine to capture carbon dioxide from the air and convert it into the slimy cement that builds each granule of cryoconite</p>
<p>However, with vast numbers of cryoconite holes dotted across the ice surface, “swarms” of these holes help <a href="https://www.frontiersin.org/articles/10.3389/feart.2015.00078/full">shape and darken the ice surface</a>. This in turn influences the melting rate, as the surface is sculpted under the sun of 24-hour daylight.</p>
<p>Writing in the scientific journal <a href="https://www.nature.com/articles/029039a0">Nature in 1883</a>, Swedish polar explorer Adolf Erik Nordenskjöld, who discovered cryoconite, thanked the organisms within cryoconite for melting away the ancient ice that once covered Norway and Sweden:</p>
<blockquote>
<p>In spite of their insignificance, [they] play a very important part in nature’s economy, from the fact that their dark colour far more readily absorbs the Sun’s heat than the bluish-white ice, and thereby they contribute to the destruction of the ice sheet, and prevent its extension. Undoubtedly we have, in no small degree, to thank these organisms for the melting away of the layer of ice which once covered the Scandinavian peninsula.</p>
</blockquote>
<h2>Taking DNA analysis to strange new places</h2>
<p>We return to Greenland in winter 2018 to explore cryoconite’s singular flaw. Cook and I are joined by Melanie Hay, then a PhD student in Arctic bioinformatics.</p>
<p>Hay and I are taking DNA analysis to strange new places to learn more about the evolution and biology of cryoconite. Powerful advances in genomics are changing our view of the microbial world, but large DNA-sequencing instruments fare best in sophisticated labs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist sitting outside her tent with backpack, looking out at icy landscape." src="https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=555&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=555&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=555&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Melanie Hay camping and sampling on the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Instead, we are using a stapler-sized nanopore sequencer hooked up to the USB port of a winterised laptop. Outside the tent, it is –20°C – but the DNA sequencer must run at body temperature. The only sustainable source of warmth is body heat, so I have snuggled up with the sequencer in my sleeping bag every night and in my clothes all day.</p>
<p>That evening, we are caught in a storm of hurricane force. Becoming disorientated while moving between tents would be lethal, so we crawl in a human chain through the whiteout to our sleeping tents. Hay reaches her tent but Cook’s is lost, so we squeeze into my one-person tent. Somehow I sleep soundly, while Cook is exposed to the full force of the night’s terror.</p>
<p>In the morning, we excavate Hay, whose snow-laden tent had collapsed in the night. The sequencing is complete, but storm damage to our generator means the camp is losing power, so she must work quickly. She identifies the cyanobacteria building the cryoconite – it’s a short list dominated by one species: <em>Phormidesmis priestleyi</em>.</p>
<p>This species, found in cryoconite throughout the Arctic, seems to be the ecosystem engineer of cryoconite – a microscopic beaver building a dam of dust. But the flaw is the darkness of the near-perfect cryoconite ecosystems it creates. Like the neighbouring glacier algae we met earlier, <em>Phormidesmis priestleyi</em> is biologically darkening Arctic ice, and eventually hastening the demise of the thousands of different types of organism contained in cryoconite holes.</p>
<p>And so, this work shows us ever more clearly that the <a href="https://www.nature.com/articles/s41559-020-1163-0">loss of the planet’s glaciers</a> is as much a component of the global biodiversity crisis as it is a headline impact of climate change.</p>
<h2>Last line of defence against antibiotic resistance</h2>
<p>The loss of the Arctic’s microbial biodiversity matters in other ways too. Hay and Aliyah Debbonaire are both reformed biomedical scientists seeking cures from the Arctic in the form of new antibiotics. In the summer of 2018, we are in Svalbard looking for clues.</p>
<p>The world is running out of effective antibiotics, and the Arctic’s frontiers may be our last line of defence in this antibiotic resistance crisis. Countless species of microbes have evolved to live within its harsh habitats using all the tricks in the book, including making antibiotics as chemical weapons to kill off competitors. This means they may be sources of new antibiotics.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientists (one kneeling) taking samples in the snowy Arctic landscape." src="https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=519&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=519&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=519&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Aliyah Debbonaire (left) and Melanie Hay sampling a cryoconite hole.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>And this is not their only application. From cheeses to eco-friendly biological washing powders, entire shopping aisles of products have been derived from cold-adapted microbes. As climate warming threatens to disrupt entire Arctic habitats, our opportunity to use, learn from, and protect this biodiversity may be lost forever.</p>
<p>As our tiny plane returns to the nearest town, Longyearbyen, we fly low over the <a href="https://theconversation.com/after-svalbard-why-safety-of-world-seed-vaults-is-crucial-to-future-food-security-79586">Svalbard Global Seed Vault</a>, which contains the fruits of more than 12,000 years of agriculture in the form of seeds from a million different varieties of crop. Nearby, a similar facility inside a disused coal mine stores essential computer programmes on microfilm – the ultimate backup for our data-addicted world.</p>
<p>Within a snowy kilometre, you can walk between the the alpha and omega of human innovation in civilisation. Both facilities have chosen the fastest-warming town on the planet as the safest place to store these treasures of humanity. Yet no such facility is dedicated to the microbial biodiversity of the Arctic, despite its critical importance to the future of the world’s biotech and medical sectors.</p>
<p>Instead, it falls to microbiologists such as Debbonaire, racing against time to identify, nurture and screen the microbes of the melting Arctic. Her painstaking work accumulates towers of Petri dishes, each a temporary refuge for a different Arctic microbe.</p>
<p>Eventually, they will be stored in <a href="https://www.dellamarca.it/en/how-does-an-ultra-low-freezer-work/">ultra-freezers</a> in laboratories scattered across the world. Such work is unglamorous to funders, so it is done piecemeal on the edges of other projects. Yet it represents our only attempt to save the microbes of the Arctic.</p>
<h2>The battle is lost</h2>
<p>Most of all, the Arctic matters because it is the fastest-warming part of the planet, and its microbes are responding first. What happens there carries implications for everyone. It is the harbinger of change for everywhere.</p>
<p>Another Arctic microbiologist could strike plangent notes regarding permafrost or sea ice, but as an ecologist of glaciers I am drawn to glacial ice.</p>
<p>Over the first fifth of this century, Earth’s glaciers have discharged some ten quadrillion (ten to the power 25) tablespoons of melt a year – and within each tablespoon, the <a href="https://www.nature.com/articles/s43247-022-00609-0">tens of thousands of bacteria and viruses</a> that were once stored within that ice.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meltwater-is-infiltrating-greenlands-ice-sheet-through-millions-of-hairline-cracks-destabilizing-its-structure-207468">Meltwater is infiltrating Greenland’s ice sheet through millions of hairline cracks – destabilizing its structure</a>
</strong>
</em>
</p>
<hr>
<p>What’s to come is sadly predictable. Even the most modest warming scenario of 1.5°C above the pre-industrial era will lead to the extinction of at least <a href="https://www.science.org/doi/10.1126/science.abo1324">half the Earth’s 200,000 glaciers</a> by the end of the century.</p>
<p>Depending on the urgency and effectiveness of our actions as a civilisation, this century could also represent the “peak melt” in our history. Yet the battle to save many of these precious icy habitats is already lost. Instead, for scientists like me, our field work is now largely a question of documenting these “crime scenes” – so at least the knowledge of life within ice can be preserved, before it melts away forever.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=112&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=112&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=112&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=140&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=140&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=140&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>For you: more from our <a href="https://theconversation.com/uk/topics/insights-series-71218?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Insights series</a>:</em></p>
<ul>
<li><p><em><a href="https://theconversation.com/prehistoric-communities-off-the-coast-of-britain-embraced-rising-seas-what-this-means-for-todays-island-nations-147879?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Prehistoric communities off the coast of Britain embraced rising seas – what this means for today’s island nations
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</a></em></p></li>
<li><p><em><a href="https://theconversation.com/noise-in-the-brain-enables-us-to-make-extraordinary-leaps-of-imagination-it-could-transform-the-power-of-computers-too-192367?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Noise in the brain enables us to make extraordinary leaps of imagination. It could transform the power of computers too
</a></em></p></li>
<li><p><em><a href="https://theconversation.com/beyond-gdp-changing-how-we-measure-progress-is-key-to-tackling-a-world-in-crisis-three-leading-experts-186488?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Beyond GDP: changing how we measure progress is key to tackling a world in crisis – three leading experts
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<p><em>To hear about new Insights articles, join the hundreds of thousands of people who value The Conversation’s evidence-based news. <a href="https://theconversation.com/uk/newsletters/the-daily-newsletter-2?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK"><strong>Subscribe to our newsletter</strong></a>.</em></p><img src="https://counter.theconversation.com/content/207785/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arwyn Edwards receives funding from UK Research & Innovation - Natural Environment Research Council, as well as the Research Council of Norway, the Leverhulme Trust, and the Royal Geographical Society. </span></em></p>
To fully understand the extent of climate-related dangers the Arctic – and our planet – is facing, we must focus on organisms too small to be seen with the naked eye.
Arwyn Edwards, Reader in Biology, Department of Life Sciences, Aberystwyth University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/196254
2022-12-13T16:01:45Z
2022-12-13T16:01:45Z
Arctic Report Card 2022: The Arctic is getting rainier and seasons are shifting, with broad disturbances for people, ecosystems and wildlife
<figure><img src="https://images.theconversation.com/files/500768/original/file-20221213-10619-mim3qd.jpg?ixlib=rb-1.1.0&rect=24%2C8%2C5439%2C3628&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rainier winters make life more difficult for Arctic wildlife and the humans who rely on them.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/reindeer-herd-in-mid-winter-norwegian-arctic-january-27th-news-photo/608180463">Scott Wallace/Getty Image</a></span></figcaption></figure><p>In the Arctic, the freedom to travel, hunt and make day-to-day decisions is profoundly tied to cold and frozen conditions for much of the year. These conditions are rapidly changing as the Arctic warms.</p>
<p>The Arctic is now seeing more rainfall when historically it would be snowing. Sea ice that once protected coastlines from erosion during fall storms is forming later. And thinner river and lake ice is making travel by snowmobile increasingly life-threatening. </p>
<p>Ship traffic in the Arctic is also increasing, bringing new risks to fragile ecosystems, and the Greenland ice sheet is continuing to send freshwater and ice into the ocean, raising global sea level</p>
<p>In the annual <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022">Arctic Report Card</a>, released Dec. 13, 2022, we brought together 144 other Arctic scientists from 11 countries to examine the current state of the Arctic system.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/500559/original/file-20221212-1585-avllq2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/500559/original/file-20221212-1585-avllq2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500559/original/file-20221212-1585-avllq2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500559/original/file-20221212-1585-avllq2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500559/original/file-20221212-1585-avllq2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500559/original/file-20221212-1585-avllq2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500559/original/file-20221212-1585-avllq2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500559/original/file-20221212-1585-avllq2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some of the Arctic headlines of 2022 discussed in the Arctic Report Card.</span>
<span class="attribution"><span class="source">NOAA Climate.gov</span></span>
</figcaption>
</figure>
<h2>The Arctic is getting wetter and rainier</h2>
<p>We found that <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/993/Precipitation">Arctic precipitation is on the rise across all seasons</a>, and these seasons are shifting. </p>
<p>Much of this new precipitation is now falling as rain, sometimes during winter and traditionally frozen times of the year. This disrupts daily life for humans, wildlife and plants. </p>
<p>Roads become dangerously icy more often, and communities face greater risk of river flooding events. For Indigenous reindeer herding communities, winter rain can create an impenetrable ice layer that prevents their reindeer from accessing vegetation beneath the snow. </p>
<figure class="align-center ">
<img alt="Map shows significant increases in precipitation across the Arctic in both winter and fall." src="https://images.theconversation.com/files/500588/original/file-20221213-3149-u7oobq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500588/original/file-20221213-3149-u7oobq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=830&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500588/original/file-20221213-3149-u7oobq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=830&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500588/original/file-20221213-3149-u7oobq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=830&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500588/original/file-20221213-3149-u7oobq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1043&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500588/original/file-20221213-3149-u7oobq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1043&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500588/original/file-20221213-3149-u7oobq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1043&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.arctic.noaa.gov/Report-Card">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>Arctic-wide, this shift toward wetter conditions can disrupt the lives of animals and plants that have evolved for dry and cold conditions, potentially altering Arctic peoples’ local foods.</p>
<p>When Fairbanks, Alaska, got 1.4 inches of freezing rain in December 2021, the moisture created an ice layer that persisted for months, bringing down trees and disrupting travel, infrastructure and the ability of some Arctic animals to forage for food. The resulting ice layer was largely <a href="https://www.ktoo.org/2022/12/06/one-third-delta-junction-bison-starve/">responsible for the deaths of a third of a bison herd</a> in interior Alaska.</p>
<p>There are multiple reasons for this increase in Arctic precipitation.</p>
<p>As sea ice rapidly declines, more open water is exposed, which feeds increased moisture into the atmosphere. The entire Arctic region has seen a more than <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/989/Sea-Ice">40% loss in summer sea ice extent</a> over the 44-year satellite record.</p>
<p>The Arctic atmosphere is also warming <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/992/Surface-Air-Temperature">more than twice as fast as the rest of the globe</a>, and this warmer air can hold more moisture. </p>
<figure class="align-center ">
<img alt="Map and time series chart show the continuing decline of the maximum extent of Arctic sea ice." src="https://images.theconversation.com/files/500769/original/file-20221213-15012-yusnzh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500769/original/file-20221213-15012-yusnzh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=983&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500769/original/file-20221213-15012-yusnzh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=983&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500769/original/file-20221213-15012-yusnzh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=983&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500769/original/file-20221213-15012-yusnzh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1235&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500769/original/file-20221213-15012-yusnzh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1235&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500769/original/file-20221213-15012-yusnzh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1235&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.arctic.noaa.gov/Report-Card">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>Under the ground, the wetter, rainier Arctic is accelerating the <a href="https://theconversation.com/thawing-permafrost-is-roiling-the-arctic-landscape-driven-by-a-hidden-world-of-changes-beneath-the-surface-as-the-climate-warms-174157">thaw of permafrost</a>, upon which most Arctic communities and infrastructure are built. The result is crumbling buildings, sagging and cracked roads, the emergence of sinkholes and the collapse of community coastlines along rivers and ocean. </p>
<p>Wetter weather also disrupts the building of a reliable winter snowpack and safe, reliable river ice, and often challenges Indigenous communities’ efforts to <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2019/ArtMID/7916/ArticleID/850/Voices-from-the-Front-Lines-of-a-Changing-Bering-Sea">harvest and secure their food</a>.</p>
<p>When <a href="https://theconversation.com/typhoon-merbok-fueled-by-unusually-warm-pacific-ocean-pounded-alaskas-vulnerable-coastal-communities-at-a-critical-time-190898">Typhoon Merbok</a> hit in September 2022, fueled by unusually warm Pacific water, its hurricane-force winds, 50-foot waves and far-reaching storm surge damaged homes and infrastructure over 1,000 miles of Bering Sea coastline, and disrupted hunting and harvesting at a crucial time.</p>
<figure class="align-center ">
<img alt="Globe and time series chart show temperatures rising faster across the Arctic than in the rest of the world." src="https://images.theconversation.com/files/500589/original/file-20221213-900-rbisur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500589/original/file-20221213-900-rbisur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=774&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500589/original/file-20221213-900-rbisur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=774&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500589/original/file-20221213-900-rbisur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=774&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500589/original/file-20221213-900-rbisur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=972&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500589/original/file-20221213-900-rbisur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=972&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500589/original/file-20221213-900-rbisur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=972&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.arctic.noaa.gov/Report-Card">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<h2>Arctic snow season is shrinking</h2>
<p>Snow plays critical roles in the Arctic, and the snow season is shrinking.</p>
<p>Snow helps to keep the Arctic cool by reflecting incoming solar radiation back to space, rather than allowing it to be absorbed by the darker snow-free ground. Its presence helps <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/1002/Lake-Ice">lake ice last longer into spring</a> and helps the land to retain moisture longer into summer, preventing overly dry conditions that are ripe for <a href="https://uaf-iarc.org/2022/12/a-future-of-more-wildfires-in-alaska/">devastating wildfires</a>.</p>
<p>Snow is also a travel platform for hunters and a habitat for many animals that rely on it for nesting and protection from predators.</p>
<p>A <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/991/Terrestrial-Snow-Cover">shrinking snow season</a> is disrupting these critical functions. For example, the June snow cover extent across the Arctic is declining at a rate of nearly 20% per decade, marking a dramatic shift in how the snow season is defined and experienced across the North. </p>
<p>Even in the depth of winter, warmer temperatures are breaking through. The far northern Alaska town of Utqiaġvik hit 40 degrees Fahrenheit (4.4 C) – <a href="https://www.washingtonpost.com/weather/2022/12/06/alaska-winter-temperature-record-utqiagvik/">8 F above freezing</a> – on Dec. 5, 2022, even though the sun does not breach the horizon from mid-November through mid-January.</p>
<figure class="align-center ">
<img alt="Map and time series chart show how June snowfall has decreased since the late 1970s." src="https://images.theconversation.com/files/500590/original/file-20221213-22-drdove.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500590/original/file-20221213-22-drdove.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=863&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500590/original/file-20221213-22-drdove.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=863&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500590/original/file-20221213-22-drdove.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=863&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500590/original/file-20221213-22-drdove.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1085&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500590/original/file-20221213-22-drdove.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1085&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500590/original/file-20221213-22-drdove.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1085&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.arctic.noaa.gov/Report-Card">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>Fatal falls through thin sea, lake and river ice are <a href="https://doi.org/10.1093/pubmed/fdt081">on the rise</a> across Alaska, resulting in immediate tragedies as well as adding to the <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/1001/Consequences-of-Rapid-Environmental-Arctic-Change-for-People">cumulative human cost of climate change</a> that Arctic Indigenous peoples are now experiencing on a generational scale.</p>
<h2>Greenland ice melt means global problems</h2>
<p>The impacts of Arctic warming are not limited to the Arctic. In 2022, the <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/990/Greenland-Ice-Sheet">Greenland ice sheet lost ice for the 25th consecutive year</a>. This adds to rising seas, which escalates the danger coastal communities around the world must plan for to mitigate flooding and storm surge.</p>
<p>In early September 2022, the Greenland ice sheet experienced an <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/990/Greenland-Ice-Sheet">unprecedented late-season melt event across 36% of the ice sheet surface</a>. This was followed by another, even later melt event that same month, caused by the remnants of Hurricane Fiona moving up along eastern North America.</p>
<p>International <a href="https://omg.jpl.nasa.gov/portal/">teams of scientists</a> are dedicated to assessing the scale to which the Greenland ice sheet’s ice formation and ice loss are out of balance. They are also increasingly learning about the transformative role that warming ocean waters play.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/500374/original/file-20221212-105279-65pkn0.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/500374/original/file-20221212-105279-65pkn0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500374/original/file-20221212-105279-65pkn0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500374/original/file-20221212-105279-65pkn0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500374/original/file-20221212-105279-65pkn0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500374/original/file-20221212-105279-65pkn0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500374/original/file-20221212-105279-65pkn0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500374/original/file-20221212-105279-65pkn0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">NOAA Climate.gov</span></span>
</figcaption>
</figure>
<p>This year’s Arctic Report Card includes <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/1007/Lessons-From-Oceans-Melting-Greenland-a-NASA-Airborne-Mission">findings from the NASA Oceans Melting Greenland (OMG) mission</a> that has confirmed that warming ocean temperatures are increasing ice loss at the edges of the ice sheet.</p>
<h2>Human-caused change is reshaping the Arctic</h2>
<p>We are living in a new geological age — <a href="https://nap.nationalacademies.org/catalog/18726/the-arctic-in-the-anthropocene-emerging-research-questions">the Anthropocene</a> — in which human activity is the dominant influence on our climate and environments.</p>
<p>In the warming Arctic, this requires decision-makers to better anticipate the interplay between a changing climate and human activity. For example, satellite-based ship data since 2009 clearly show that <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/1004/Satellite-Record-of-Pan-Arctic-Maritime-Ship-Traffic">maritime ship traffic</a> has increased within all Arctic high seas and national exclusive economic zones as the region has warmed.</p>
<figure class="align-center ">
<img alt="Map shows increase in ship traffic in Arctic regions since 2009, with a nearly 50% increase in shipping around Norway and over 12% increase near Russia. Paired with a photo of a ship in sea ice." src="https://images.theconversation.com/files/500591/original/file-20221213-23-cximvx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500591/original/file-20221213-23-cximvx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=805&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500591/original/file-20221213-23-cximvx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=805&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500591/original/file-20221213-23-cximvx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=805&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500591/original/file-20221213-23-cximvx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1012&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500591/original/file-20221213-23-cximvx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1012&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500591/original/file-20221213-23-cximvx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1012&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.arctic.noaa.gov/Report-Card">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>For these ecologically sensitive waters, this added ship traffic raises urgent concerns ranging from the future of Arctic trade routes to the introduction of even more human-caused stresses on Arctic peoples, ecosystems and the climate. These concerns are especially pronounced given uncertainties regarding the current geopolitical tensions between Russia and the other Arctic states over its war in Ukraine.</p>
<p>Rapid Arctic warming requires new forms of partnership and information sharing, including <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/8054/ArticleID/1001/Consequences-of-Rapid-Environmental-Arctic-Change-for-People">between scientists and Indigenous knowledge-holders</a>. Cooperation and building resilience can help to reduce some risks, but global action to rein in greenhouse gas pollution is essential for the entire planet.</p><img src="https://counter.theconversation.com/content/196254/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew Druckenmiller receives research funding from the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA). </span></em></p><p class="fine-print"><em><span>Rick Thoman receives funding from NOAA/Arctic Program</span></em></p><p class="fine-print"><em><span>Twila Moon receives research funding from the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA).</span></em></p>
The annual report is also a reminder that what happens in the Arctic affects the rest of the world.
Matthew L. Druckenmiller, Research Scientist, National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder
Rick Thoman, Alaska Climate Specialist, University of Alaska Fairbanks
Twila A. Moon, Deputy Lead Scientist, National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/189946
2022-09-08T12:31:46Z
2022-09-08T12:31:46Z
Ghost islands of the Arctic: The world’s ‘northern-most island’ isn’t the first to be erased from the map
<figure><img src="https://images.theconversation.com/files/482580/original/file-20220902-20-ywtp99.JPG?ixlib=rb-1.1.0&rect=0%2C9%2C2015%2C1270&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">These 'islands' are on the move.</span> <span class="attribution"><span class="source">Martin Nissen</span></span></figcaption></figure><p>In 2021, an expedition off the icy northern Greenland coast spotted what appeared to be a previously uncharted island. It was small and gravelly, and it was declared a contender for the title of the most northerly known land mass in the world. The discoverers named it <a href="https://www.smithsonianmag.com/smart-news/scientists-set-foot-worlds-northernmost-island-180978566/">Qeqertaq Avannarleq</a> – Greenlandic for “the northern most island.”</p>
<p>But there was a mystery afoot in the region. Just north of Cape Morris Jesup, several other small islands had been discovered over the decades, and then disappeared.</p>
<p>Some scientists theorized that these were rocky banks that had been pushed up by sea ice. </p>
<p>But when a team of Swiss and Danish surveyors traveled north to <a href="https://www.arctictoday.com/several-islands-recorded-as-the-northernmost-on-earth-are-most-likely-icebergs-and-will-disappear-again/">investigate this “ghost islands”</a> phenomenon, they discovered something else entirely. They <a href="https://www.space.dtu.dk/nyheder/nyhed?id=3767be72-335e-4f02-a277-87a39aaf5ffe">announced their findings</a> in September 2022: These elusive islands are actually large icebergs grounded at the sea bottom. They likely came from a nearby glacier, where other newly calved icebergs, covered with gravel from landslides, were ready to float off. </p>
<p>This was not the first such disappearing act in the high Arctic, or the first need to erase land from the map. Nearly a century ago, an innovative airborne expedition redrew the maps of large swaths of the Barents Sea.</p>
<h2>The view from a zeppelin in 1931</h2>
<p>The 1931 expedition emerged from American newspaper magnate William Randolph Hearst’s plan for a spectacular publicity stunt. </p>
<p>Hearst proposed having <a href="https://www.airships.net/lz127-graf-zeppelin/">the Graf Zeppelin</a>, then the world’s largest airship, fly to the North Pole for a meeting with a submarine that would travel under the ice. This ran into practical difficulties and Hearst abandoned the plan, but the notion of using the Graf Zeppelin to conduct <a href="https://www.jstor.org/stable/209526">geographic and scientific investigations</a> of the high Arctic was taken up by an international polar science committee.</p>
<p>The airborne expedition they devised would employ pioneering technologies and make important geographical, meteorological and magnetic discoveries in the Arctic – including remapping much of the Barents Sea. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/oVP2pZX2yGo?wmode=transparent&start=185" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The expedition was known as the Polarfahrt – “polar voyage” in German. Despite the international tensions at the time, the zeppelin carried a team of German, Soviet and U.S. scientists and explorers. </p>
<p>Among them were <a href="https://en.wikipedia.org/wiki/Lincoln_Ellsworth">Lincoln Ellsworth</a>, a wealthy American and experienced Arctic explorer who would write the <a href="https://www.jstor.org/stable/209526">first scholarly account</a> of the Polarfahrt and its geographical discoveries. Two important Soviet scientists also participated: the brilliant meteorologist <a href="https://en.wikipedia.org/wiki/Pavel_Molchanov">Pavel Molchanov</a> and the expedition’s chief scientist, Rudolf Samoylovich, who <a href="https://hgss.copernicus.org/articles/4/35/2013/">performed magnetic measurements</a>. In charge of the meteorological operations was Ludwig Weickmann, director of the Geophysical Institute of the University of Leipzig.</p>
<p>The expedition’s chronicler was Arthur Koestler, a young journalist who would later become famous for his anti-communist novel “Darkness at Noon,” depicting totalitarianism turning on its own party loyalists.</p>
<figure class="align-center ">
<img alt="The giant airship in a hangar with people standing beside it looking very tiny" src="https://images.theconversation.com/files/482818/original/file-20220905-14-ohmst6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482818/original/file-20220905-14-ohmst6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482818/original/file-20220905-14-ohmst6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482818/original/file-20220905-14-ohmst6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482818/original/file-20220905-14-ohmst6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482818/original/file-20220905-14-ohmst6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482818/original/file-20220905-14-ohmst6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Built in 1928 and longer than two football fields, the Graf Zeppelin was normally used for ultra-luxurious commercial passenger transportation. Financing for the science mission came in part from the sale of postcards with stamps specially issued by the postal authorities of Germany and the Soviet Union.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Zeppelin_Graf_Zeppelin.jpg">Wikimedia</a></span>
</figcaption>
</figure>
<p>The five-day trip took them north over the Barents Sea as far as 82 degrees north latitude, and then eastward for hundreds of miles before returning southwestward.</p>
<p>Koestler provided daily reports via shortwave radio that appeared in newspapers around the world.</p>
<blockquote>
<p>“The experience of this swift, silent and effortless rising, or rather falling upwards into the sky, is beautiful and intoxicating,” Koestler wrote in <a href="https://ebin.pub/arrow-in-the-blue-an-autobiography-1.html">his 1952 autobiography</a>. “… it gives one the complete illusion of having escaped the bondage of the earth’s gravity.</p>
<p>"We hovered in the Arctic air for several days, moving at a leisurely average of 60 miles per hour and often stopping in mid-air to complete a photographic survey or release small weather balloons. It all had a charm and a quiet excitement comparable to a journey on the last sailing ship in an era of speed boats.”</p>
</blockquote>
<h2>‘The disadvantage of not existing’</h2>
<p>The high latitude regions the Polarfahrt passed over were incredibly remote. In the late 19th century, Austrian explorer Julius von Payer reported the discovery of Franz Josef Land, an archipelago of nearly 200 islands in the Barents Sea, but initially there had been <a href="https://english.radio.cz/julius-von-payer-teplice-born-explorer-who-discovered-franz-josef-land-8113568">doubts about Franz Josef Land’s existence</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/482577/original/file-20220902-25-23tpvq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map showing Franz Josef Land in relation to Greenland and Russia." src="https://images.theconversation.com/files/482577/original/file-20220902-25-23tpvq.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/482577/original/file-20220902-25-23tpvq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=556&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482577/original/file-20220902-25-23tpvq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=556&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482577/original/file-20220902-25-23tpvq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=556&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482577/original/file-20220902-25-23tpvq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=699&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482577/original/file-20220902-25-23tpvq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=699&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482577/original/file-20220902-25-23tpvq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=699&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Franz_Josef_Land_location-en.svg">Oona Räisänen via Wikimedia</a></span>
</figcaption>
</figure>
<p>The Polarfahrt confirmed the existence of Franz Josef Land, but it would reveal that the maps produced by the early explorers of the high Arctic had startling deficiencies.</p>
<p>For the expedition, the Graf Zeppelin had been outfitted with wide-angle cameras that allowed detailed photography of the surface below. The slowly moving Zeppelin was ideally suited for this purpose and could make leisurely surveys that were not possible from fixed-wing aircraft overflights.</p>
<blockquote>
<p>“We spent the remainder of [July 27] making a geographical survey of Franz Josef Land,” <a href="https://ebin.pub/arrow-in-the-blue-an-autobiography-1.html">Koestler wrote</a>. </p>
<p>“Our first objective was an island called Albert Edward Land. But that was easier said than done, for Albert Edward Land had the disadvantage of not existing. It could be found on every map of the Arctic, but not in the Arctic itself …</p>
<p>"Next objective: Harmsworth Land. Funny as it sounds Harmsworth Land didn’t exist either. Where it ought to have been, there was nothing but the black polar sea and the reflection of the white Zeppelin.</p>
<p>"Heaven knows whether the explorer who put these islands on the map (I believe it was Payer) had been a victim of a mirage, mistaking some icebergs for land … At any rate, as of July 27, 1931, they have been officially erased.”</p>
</blockquote>
<p>The expedition would also discover six islands and redraw the coastal outlines of many others. </p>
<h2>A revolutionary way to measure the atmosphere</h2>
<p>The expedition was also remarkable for the instruments Molchanov tested aboard the Graf Zeppelin – including his newly invented “radiosondes.” His technology would revolutionize meteorological observations and led to instruments that <a href="http://iprc.soest.hawaii.edu/people/hamilton.php">atmospheric scientists like me</a> rely on today.</p>
<p>Until 1930, measuring the temperature high in the atmosphere was extremely challenging for meteorologists.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/482816/original/file-20220905-21-2jk3mi.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482816/original/file-20220905-21-2jk3mi.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=440&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482816/original/file-20220905-21-2jk3mi.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=440&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482816/original/file-20220905-21-2jk3mi.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=440&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482816/original/file-20220905-21-2jk3mi.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=553&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482816/original/file-20220905-21-2jk3mi.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=553&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482816/original/file-20220905-21-2jk3mi.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=553&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Pavel Molchanov and Ludwig Weickmann prepare to launch a weather balloon.</span>
<span class="attribution"><a class="source" href="https://radiosondemuseum.org">Radiosonde Museum of North America</a></span>
</figcaption>
</figure>
<p>They used so-called <a href="https://repository.si.edu/bitstream/handle/10088/2453/SSHT-0053_Lo_res.pdf?sequence=2">registering sondes</a> that recorded the temperature and pressure by weather balloon. A stylus would make a continuous trace on paper or some other medium, but to read it, scientists would have to find the sonde package after it dropped, and it typically drifted many miles from the launch point. This was particularly impractical in remote areas such as the Arctic.</p>
<p>Molchanov’s device could radio back the temperature and pressure at frequent intervals during the balloon flight. Today, balloon-borne radiosondes are launched <a href="https://courses.imperativemoocs.com/monitoring-the-oceans-from-space-01/week-1-oceans-and-climate/topic-1c-climate-change/global-radiosonde-network">daily at several hundred stations worldwide</a>. </p>
<p>The Polarfahrt was Molchanov’s chance for a spectacular demonstration. The Graf Zeppelin generally flew in the lowest few thousand feet of the atmosphere, but could serve as a platform to release weather balloons that could ascend much higher, acting as remotely reporting “robots” in the upper atmosphere. </p>
<figure class="align-center ">
<img alt="A balloon is launched from below the airship" src="https://images.theconversation.com/files/482817/original/file-20220905-14-nvf176.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482817/original/file-20220905-14-nvf176.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482817/original/file-20220905-14-nvf176.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482817/original/file-20220905-14-nvf176.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482817/original/file-20220905-14-nvf176.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482817/original/file-20220905-14-nvf176.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482817/original/file-20220905-14-nvf176.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">To launch radiosondes from the zeppelin, weather balloons were weighted to sink at first. The weight was designed to drop off, allowing the balloon to later rise through the atmosphere.</span>
<span class="attribution"><a class="source" href="https://radiosondemuseum.org">Radiosonde Museum of North America.</a></span>
</figcaption>
</figure>
<p>Molchanov’s hydrogen-filled weather balloons provided the first observations of the stratospheric temperatures near the pole. Remarkably, he found that at heights of 10 miles the air at the pole was actually <a href="https://bulletin.cmos.ca/early-exploration-of-the-high-latitude-stratosphere-part-i-pre-world-war-ii-era/">much warmer than at the equator</a>.</p>
<h2>Fate of the protagonists</h2>
<p>The Polarfahrt was a final flourish of international scientific cooperation at the beginning of the 1930s, a period that saw a catastrophic rise of authoritarian politics and international conflict. By 1941, the U.S., Soviet Union and Germany would all be at war.</p>
<p><a href="http://www.edubilla.com/inventor/pavel-molchanov/">Molchanov</a> and <a href="https://en.wikipedia.org/wiki/Rudolf_Samoylovich">Samoylovich</a> became victims of Stalin’s secret police. As a Hungarian Jew, <a href="https://www.orwellfoundation.com/the-orwell-foundation/orwell/essays-and-other-works/arthur-koestler/">Koestler</a> would have his life and career shadowed by the politics of the age. He eventually found refuge in England, where he built a career as a novelist, <a href="https://en.wikipedia.org/wiki/The_Yogi_and_the_Commissar">essayist</a> and <a href="https://en.wikipedia.org/wiki/The_Sleepwalkers_(Koestler_book)">historian of science</a>.</p>
<p>The Graf Zeppelin continued in commercial passenger service principally on trans-Atlantic flights. But <a href="https://archive.org/details/hindenburg00moon">one of history’s most iconic tragedies</a> soon ended the era of zeppelin travel. In May 1937, the Graf Zeppelin’s younger sister airship, the Hindenburg, caught fire while trying to land in New Jersey. The Graf Zeppelin was dismantled in 1940 to provide scrap metal for the German war effort.</p><img src="https://counter.theconversation.com/content/189946/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Hamilton does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The new discovery echoes a mission in 1931, when a five-day zeppelin flight sent robots to the stratosphere and redrew the maps of the high Arctic.
Kevin Hamilton, Emeritus Professor of Atmospheric Sciences, University of Hawaii
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/185590
2022-08-29T18:04:43Z
2022-08-29T18:04:43Z
What’s going on with the Greenland ice sheet? It’s losing ice faster than forecast and now irreversibly committed to at least 10 inches of sea level rise
<figure><img src="https://images.theconversation.com/files/481620/original/file-20220829-8728-38vmqp.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1415%2C488&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A turbulent melt-river pours a million tons of water a day into a moulin, where it flows down through the ice to ultimately reach the ocean.</span> <span class="attribution"><span class="source">Ted Giffords</span></span></figcaption></figure><p>I’m standing at the edge of the Greenland ice sheet, mesmerized by a mind-blowing scene of natural destruction. A milewide section of glacier front has fractured and is collapsing into the ocean, calving an immense iceberg.</p>
<p>Seracs, giant columns of ice the height of three-story houses, are being tossed around like dice. And the previously submerged portion of this immense block of glacier ice just breached the ocean – a frothing maelstrom flinging ice cubes of several tons high into the air. The resulting tsunami inundates all in its path as it radiates from the glacier’s calving front.</p>
<p>Fortunately, I’m watching from a clifftop a couple of miles away. But even here, I can feel the <a href="https://doi.org/10.1029/2008GL036127">seismic shocks through the ground</a>.</p>
<figure class="align-center ">
<img alt="A large iceberg calves off a glacier." src="https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=344&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=344&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=344&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=433&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=433&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=433&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A fast-flowing outlet glacier calves a ‘megaberg’ into Greenland’s Uummannaq Fjord.</span>
<span class="attribution"><span class="source">Alun Hubbard</span></span>
</figcaption>
</figure>
<p>Despite the spectacle, I’m keenly aware that this spells yet more unwelcome news for the world’s low-lying coastlines.</p>
<p>As <a href="https://cage.uit.no/employee/alun-hubbard/">a field glaciologist</a>, I’ve worked on ice sheets for more than 30 years. In that time, I have witnessed some gobsmacking changes. The past few years in particular have been unnerving for the sheer rate and magnitude of change underway. My revered textbooks taught me that ice sheets respond over millennial time scales, but that’s not what we’re seeing today.</p>
<p><a href="https://doi.org/10.1038/s41558-022-01441-2">A study published</a> Aug. 29, 2022, demonstrates – for the first time – that Greenland’s ice sheet is now so out of balance with prevailing Arctic climate that it no longer can sustain its current size. It is irreversibly committed to retreat by at least 59,000 square kilometers (22,780 square miles), an area considerably larger than Denmark, Greenland’s protectorate state.</p>
<p>Even if all the greenhouse gas emissions driving global warming ceased today, we find that Greenland’s ice loss under current temperatures will <a href="https://doi.org/10.1038/s41558-022-01441-2">raise global sea level</a> by at least 10.8 inches (27.4 centimeters). That’s more than current models forecast, and it’s a highly conservative estimate. If every year were like 2012, <a href="https://doi.org/10.5194/tc-10-1147-2016">when Greenland experienced a heat wave</a>, that irreversible commitment to sea level rise would triple. That’s an ominous portent given that these are climate conditions we have already seen, not a hypothetical future scenario.</p>
<p>Our study takes a completely new approach – it is based on observations and glaciological theory rather than sophisticated numerical models. The current generation of <a href="https://doi.org/10.5194/tc-15-5705-2021">coupled climate and ice sheet models used to forecast future sea level rise fail</a> to capture the emerging processes that we see amplifying Greenland’s ice loss.</p>
<h2>How Greenland got to this point</h2>
<p>The <a href="http://nsidc.org/greenland-today/">Greenland ice sheet</a> is a massive, frozen reservoir that resembles an inverted pudding bowl. The ice is in <a href="https://doi.org/10.1002/2013GL058933">constant flux</a>, flowing from the interior – where it is over 1.9 miles (3 kilometers) thick, cold and snowy – to its edges, where the ice melts or calves bergs.</p>
<p>In all, the ice sheet locks up enough fresh water to <a href="https://doi.org/10.1002/2017GL074954">raise global sea level</a> by 24 feet (7.4 meters).</p>
<figure>
<iframe src="https://player.vimeo.com/video/743951647" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">David Attenborough takes us on a virtuoso tour of the Greenland ice sheet.</span></figcaption>
</figure>
<p>Greenland’s <a href="https://doi.org/10.1038/307620a0">terrestrial ice has existed for about 2.6 million years and has expanded and contracted with two dozen or so “ice age” cycles</a> lasting 70,000 or 100,000 years, punctuated by around 10,000-year warm interglacials. Each glacial is driven by <a href="https://climate.nasa.gov/ask-nasa-climate/2949/why-milankovitch-orbital-cycles-cant-explain-earths-current-warming">shifts in Earth’s orbit</a> <a href="https://doi.org/10.1126%2Fscience.194.4270.1121">that modulate</a> how much solar radiation reaches the Earth’s surface. These variations are then reinforced by snow reflectivity, or albedo; atmospheric greenhouse gases; and ocean circulation that redistributes that heat around the planet.</p>
<p>We are currently enjoying an interglacial period – the Holocene. For the past 6,000 years Greenland, like the rest of the planet, has benefited from a mild and stable climate with an ice sheet in equilibrium – until recently. Since 1990, as the atmosphere and ocean have warmed under rapidly increasing greenhouse gas emissions, Greenland’s mass balance has gone into the red. Ice losses due to enhanced melt, rain, ice flow and calving now far exceed the net gain from snow accumulation.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/stm1pBp0rfk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Greenland’s ice mass loss measured by NASA’s Grace satellites.</span></figcaption>
</figure>
<h2>What does the future hold?</h2>
<p>The critical questions are, how fast is Greenland losing its ice, and what does it mean for future sea level rise?</p>
<p>Greenland’s ice loss has been <a href="https://doi.org/10.1002/2017GL074954">contributing about 0.04 inches</a> (1 millimeter) per year to <a href="https://www.ipcc.ch/srocc/chapter/chapter-4-sea-level-rise-and-implications-for-low-lying-islands-coasts-and-communities/">global sea level rise</a> over the past decade.</p>
<p><a href="https://doi.org/10.1126/science.1178176">This net loss is split between surface melt and dynamic processes</a> that accelerate outlet glacier flow and are greatly exacerbated by atmospheric and oceanic warming, respectively. Though complex in its manifestation, the concept is simple: Ice sheets don’t like warm weather or baths, and the heat is on.</p>
<figure class="align-center ">
<img alt="A large area of meltwater pools on the snowy Greenland surface and forms a river and streams." src="https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=334&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=334&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=334&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=420&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=420&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=420&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Meltwater lakes feed rivers that snake across the ice sheet - until they encounter a moulin.</span>
<span class="attribution"><span class="source">Alun Hubbard</span></span>
</figcaption>
</figure>
<p>What the future will bring is trickier to answer.</p>
<p>The models used by the <a href="https://www.ipcc.ch/assessment-report/ar6/">Intergovernmental Panel on Climate Change</a> predict a sea level rise contribution from Greenland of <a href="https://doi.org/10.1029/2020GL091741">around 4 inches (10 centimeters) by 2100</a>, with a worst-case scenario of 6 inches (15 centimeters). </p>
<p>But that prediction is at odds with what field <a href="https://doi.org/10.1002/2017GL074954">scientists are witnessing from the ice sheet itself</a>. </p>
<p>According to our findings, Greenland will lose <a href="https://doi.org/10.1038/s41558-022-01441-2">at least 3.3% of its ice</a>, over 100 trillion metric tons. This loss is already committed – ice that <a href="https://www.usgs.gov/special-topics/water-science-school/science/fundamentals-water-cycle">must melt and calve icebergs</a> to reestablish Greenland’s balance with prevailing climate. </p>
<p>We’re observing many emerging processes that the models don’t account for that increase the ice sheet’s vulnerability. For example:</p>
<ul>
<li><p>Increased rain is <a href="https://doi.org/10.1038/ngeo2482">accelerating surface melt and ice flow</a>.</p></li>
<li><p>Large tracts of the ice surface are undergoing <a href="https://doi.org/10.1002/2017GL075958">bio-albedo darkening</a>, which <a href="https://doi.org/10.5194/tc-14-309-2020">accelerates surface melt</a>, as well as the impact of snow <a href="https://www.carbonbrief.org/darkening-ice-speeds-up-greenland-melt-new-research-suggests/">melting and refreezing</a> at the surface. These darker surfaces absorb more solar radiation, driving yet more melt.</p></li>
</ul>
<figure class="align-center ">
<img alt="Weather stations sit atop wet snow in Greenland" src="https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In August 2021, rain fell at the Greenland ice sheet summit for the first time on record. Weather stations across Greenland captured rapid ice melt.</span>
<span class="attribution"><a class="source" href="https://www.esa.int/ESA_Multimedia/Images/2022/06/Weather_station_high_on_the_Greenland_ice_sheet">European Space Agency</a></span>
</figcaption>
</figure>
<ul>
<li><p>Warm, subtropical-originating <a href="https://doi.org/10.5194/tc-8-1457-2014">ocean currents are intruding into Greenland’s fjords</a> and rapidly eroding outlet glaciers, undercutting and <a href="https://doi.org/10.1002/2015GL065806">destabilizing their calving fronts</a>.</p></li>
<li><p>Supraglacial lakes and river networks are draining into <a href="https://www.washingtonpost.com/climate-environment/2020/12/23/climate-moulins-greenland/">fractures and moulins</a>, bringing with them vast quantities of latent heat. This “<a href="https://doi.org/10.1029/2010GL044397">cryo-hydraulic warming</a>” within and at the base of the ice sheet softens and thaws the bed, thereby <a href="https://doi.org/10.1002/2013GL058933">accelerating interior ice flow</a> down to the margins.</p></li>
</ul>
<h2>The issue with models</h2>
<p>Part of the problem is that the models used for forecasting are mathematical abstractions that include only processes that are fully understood, quantifiable and deemed important.</p>
<p>Models reduce reality to a set of equations that are solved repeatedly on banks of very fast computers. Anyone into cutting-edge engineering – including me – knows the intrinsic value of models for experimentation and testing of ideas. But they are no substitute for reality and observation. It is apparent that current model forecasts of global sea level rise underestimate its actual threat over the 21st century. Developers are making constant improvements, but it’s tricky, and there’s a dawning realization that the complex models used for long-term sea level forecasting <a href="https://doi.org/10.1016/j.oneear.2020.11.002">are not fit for purpose</a>.</p>
<figure class="align-center ">
<img alt="Several brightly colored research tents dot a landscape with streams and snow on the ice sheet." src="https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=334&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=334&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=334&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=419&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=419&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=419&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Author Alun Hubbard’s science camp in the melt zone of the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Alun Hubbard</span></span>
</figcaption>
</figure>
<p>There are also “unknown unknowns” – those processes and feedbacks that we don’t yet realize and that models can never anticipate. They can be understood only by direct observations and literally drilling into the ice. </p>
<p>That’s why, rather than using models, we base our study on <a href="https://doi.org/10.1002/2014RG000470">proven glaciological theory</a> constrained by two decades of actual measurements from weather stations, satellites and ice geophysics.</p>
<h2>It’s not too late</h2>
<p>It’s an understatement that the societal stakes are high, and the risk is tragically real going forward. The consequences of catastrophic coastal flooding as sea level rises are still unimaginable to the majority of the billion or so people who live in low-lying coastal zones of the planet.</p>
<figure class="align-center ">
<img alt="A large sailing ship with an even larger iceberg behind it and a glacier in the distance." src="https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A large tabular iceberg that calved off Store Glacier within Uummannaq Fjord.</span>
<span class="attribution"><span class="source">Alun Hubbard</span></span>
</figcaption>
</figure>
<p>Personally, I remain hopeful that we can get on track. I don’t believe we’ve passed any doom-laden tipping point that irreversibly floods the planet’s coastlines. Of what I understand of the ice sheet and the insight <a href="https://www.nature.com/articles/s41558-022-01441-2">our new study</a> brings, it’s not too late to act. </p>
<p>But fossil fuels and emissions must be curtailed now, because time is short and the water rises – faster than forecast.</p><img src="https://counter.theconversation.com/content/185590/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alun Hubbard is also affiliated with Oulun yliopisto - The University of Oulu, Finland, Arctic Basecamp & La Venta Explorazioni.</span></em></p>
A field glaciologist explains the changes scientists are now seeing.
Alun Hubbard, Professor of Glaciology, Arctic Five Chair, University of Tromsø
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/183968
2022-07-20T12:20:39Z
2022-07-20T12:20:39Z
Human garbage is a plentiful but dangerous source of food for polar bears finding it harder to hunt seals on dwindling sea ice
<figure><img src="https://images.theconversation.com/files/469265/original/file-20220616-26-du02br.jpg?ixlib=rb-1.1.0&rect=11%2C5%2C3950%2C2488&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scenes like this one are becoming increasingly common in the Arctic.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/picture-taken-on-october-31-2018-shows-polar-bears-feeding-news-photo/1128697585">ALEXANDER GRIR/Contributor/AFP via Getty Images</a></span></figcaption></figure><p>More than 50 hungry <a href="https://tass.com/emergencies/1043985">polar bears invaded the Russian coastal village of Belushya Guba</a> over a period of three months, attracted by the local dump. Some bears entered homes and businesses by ripping doors off hinges and climbing through windows. These <a href="https://doi.org/10.1002/wsb.783">invasions have been steadily increasing in Arctic settlements</a>, though this case, in the winter of 2019, was one of the worst. While few people have been attacked, <a href="https://doi.org/10.1016/j.gecco.2020.e01320">the number of dead bears has climbed</a>. </p>
<p>I’m a <a href="https://scholar.google.com/citations?user=TUOTijQAAAAJ&hl=en&oi=sra">biologist who has studied bears</a> for the past 30 years. Over millennia, polar bears evolved an ability to locate food in the harsh Arctic climate. Now, as climate change causes a loss of sea ice, their foraging season is shorter and they’re forced onto land far more than ever before. Once on land, bears’ noses draw them into villages where they find ample unsecured food.</p>
<p><a href="https://scholar.google.com/citations?hl=en&user=iSP0d_YAAAAJ">My</a> <a href="https://scholar.google.com/citations?user=Nt6hDRMAAAAJ&hl=en&oi=ao">colleagues</a> <a href="https://scholar.google.com/citations?hl=en&user=rJ3oyPgAAAAJ">and</a> <a href="https://scholar.google.com/citations?hl=en&user=xxdom7wAAAAJ">I</a> <a href="https://scholar.google.com/citations?hl=en&user=qKKVEpoAAAAJ">recently</a> <a href="https://scholar.google.com/citations?view_op=list_works&hl=en&authuser=1&user=HfT0bVkAAAAJ&gmla=AJsN-F6wO1swTqdsYNr2Ivr6Ro4h2GznkesMa-VSsoUIntqeqWC8u8WPcpPwzn428pKdpongTj2kbF0w-6PtKEgDg9ShWcyTd38k411Zn61PtDEefeY7oiw">published</a> a paper on how human food and waste are becoming a <a href="https://doi.org/10.1017/S0030605322000278">major threat to polar bear existence</a> – and jeopardize human safety. We also offer solutions. </p>
<h2>Masters of scent and memory</h2>
<p>Polar bears live in an extremely austere environment where finding food drives their every move. To aid them in their perpetual hunt for food, polar bears have <a href="https://press.jhu.edu/books/title/3041/wild-mammals-north-america">one of the most highly developed senses of smell</a> of any animal on the planet. Their ability to detect scents from afar can be a problem, however, when the scent is not coming from seals – their main food resource. </p>
<p>Smelly substances associated with human villages can also attract polar bears. These scents include game meat hung outside homes, open dumps, barbecue grills and even bird seed. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469262/original/file-20220616-24-f4g9k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A mother polar bear and two cubs snuggle near a metal gate and trash can." src="https://images.theconversation.com/files/469262/original/file-20220616-24-f4g9k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469262/original/file-20220616-24-f4g9k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469262/original/file-20220616-24-f4g9k.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469262/original/file-20220616-24-f4g9k.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469262/original/file-20220616-24-f4g9k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469262/original/file-20220616-24-f4g9k.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469262/original/file-20220616-24-f4g9k.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Not only is this mother bear putting herself in harm’s way, but she is teaching her cubs dangerous behavior.</span>
<span class="attribution"><span class="source">© Dick Beck/Polar Bears International</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Once a polar bear has discovered a food source, it is not going to forget about it. While studies are few, work in zoos suggests bears are among the most curious mammals, investigating and exploring new objects <a href="https://doi.org/10.2307/3872860">long after other mammals have abandoned them</a>. That, coupled with their extraordinary ability to remember both the timing and locations of seasonal food opportunities, serves them very well. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469285/original/file-20220616-26-8hk1wr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A polar bear on ice with a seal carcass in its mouth." src="https://images.theconversation.com/files/469285/original/file-20220616-26-8hk1wr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469285/original/file-20220616-26-8hk1wr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469285/original/file-20220616-26-8hk1wr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469285/original/file-20220616-26-8hk1wr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469285/original/file-20220616-26-8hk1wr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469285/original/file-20220616-26-8hk1wr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469285/original/file-20220616-26-8hk1wr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">As nature intended – a young male polar bear feeds on the remains of a seal.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/young-male-polar-bear-feeding-on-the-remains-of-a-killed-news-photo/646540302">Arterra/Contributor/Universal Images Group via Getty Images</a></span>
</figcaption>
</figure>
<p>At the top of the Arctic food chain, polar bears feed largely on ringed seals (<em>Pusa hispida</em>), which feed on fish, which in turn feed on plankton. Disruption of this food chain will have <a href="https://doi.org/10.1242/jeb.228049">dire consequences for the stability of the entire ecosystem</a>. The U.S. has classified the once-abundant <a href="https://www.federalregister.gov/documents/2008/05/15/E8-11105/endangered-and-threatened-wildlife-and-plants-determination-of-threatened-status-for-the-polar-bear">polar bear as threatened</a>, meaning it is in danger of going extinct if trends continue.</p>
<h2>Disappearing sea ice</h2>
<p>Polar bears are ambush predators. They attack seals surfacing through holes in the sea ice to breathe. In the water, bears are good swimmers but not nearly agile enough to catch a fleeing seal, so they rely on sea ice as a platform from which to hunt.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/470605/original/file-20220623-51375-5klmwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Side by side maps comparing sea ice from 1980 and 2020. The ice in the 2020 map looks to be roughly half the size of the 1980 map." src="https://images.theconversation.com/files/470605/original/file-20220623-51375-5klmwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/470605/original/file-20220623-51375-5klmwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/470605/original/file-20220623-51375-5klmwj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/470605/original/file-20220623-51375-5klmwj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/470605/original/file-20220623-51375-5klmwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/470605/original/file-20220623-51375-5klmwj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/470605/original/file-20220623-51375-5klmwj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Maps show Arctic sea ice on Sept. 1, 1980, and Sept. 1, 2020.</span>
<span class="attribution"><span class="source">Map from ClimateReanalyzer.org, Climate Change Institute, University of Maine. Data credit to Sea Ice Index, Version 3, National Snow and Ice Data Center.</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Climate change has caused an alarming decrease in polar sea ice. Approximately <a href="https://doi.org/10.1890/14-1129.1">40% less ice exists today than only three decades ago</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/470836/original/file-20220624-18-zw9nbf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Side by side maps comparing the thickness of sea ice from 1985 and 2021. The ice in the 2021 map is considerably thinner than that of the 1984 map." src="https://images.theconversation.com/files/470836/original/file-20220624-18-zw9nbf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/470836/original/file-20220624-18-zw9nbf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/470836/original/file-20220624-18-zw9nbf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/470836/original/file-20220624-18-zw9nbf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/470836/original/file-20220624-18-zw9nbf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=462&fit=crop&dpr=1 754w, https://images.theconversation.com/files/470836/original/file-20220624-18-zw9nbf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=462&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/470836/original/file-20220624-18-zw9nbf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=462&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Maps from National Oceanic and Atmospheric Administration Climate show decreasing coverage of longstanding perennial ice in the Arctic between March 1985 and 2021.</span>
<span class="attribution"><span class="source">Data credit to Sea Ice Index, Version 3, National Snow and Ice Data Center.</span></span>
</figcaption>
</figure>
<p>Not only does less sea ice cover the Arctic Ocean, but what remains <a href="https://www.climate.gov/news-features/videos/arctics-oldest-ice-vanishing">is not as thick as it used to be</a> – a prelude to what will eventually become an ice-free Arctic basin. When that happens, all polar bears will be forced ashore, without the ability to hunt seals.</p>
<p>Polar bears’ cruising the shores and entering human settlements are direct results of reduced sea ice – and the loss of hunting opportunities that come with it. </p>
<h2>The threat of unsecured garbage</h2>
<p>Indigenous peoples and more recent arrivals make up the <a href="https://www.arctic-council.org/explore/topics/arctic-peoples/">nearly 4 million people living throughout the Arctic</a> in the countries of Russia, Norway, Greenland, Canada and the U.S. The economies of these <a href="https://www.arctic-council.org/explore/topics/arctic-peoples/">villages are largely subsistence-based</a> and are by no means affluent. Historically, <a href="https://www.researchgate.net/profile/Alex-Zahara/publication/273771889_The_Arctic_Wastes/links/59e685c4aca2721fc227acd3/The-Arctic-Wastes.pdf">food was never discarded in these areas</a>. But today’s throwaway global economy has resulted in dumps full of waste, including foodstuffs. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469359/original/file-20220616-13-q6fbdf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A massive dump with the Arctic ocean in the background." src="https://images.theconversation.com/files/469359/original/file-20220616-13-q6fbdf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469359/original/file-20220616-13-q6fbdf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469359/original/file-20220616-13-q6fbdf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469359/original/file-20220616-13-q6fbdf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469359/original/file-20220616-13-q6fbdf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469359/original/file-20220616-13-q6fbdf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469359/original/file-20220616-13-q6fbdf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The garbage dump of Ilulissat and the Disko Bay, Greenland.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/view-over-the-garbage-dump-of-ilulissat-and-the-disko-bay-news-photo/838083236">Education Images/Contributor/Universal Images Group via Getty Images</a></span>
</figcaption>
</figure>
<p>When polar bears enter these dumps in search of food, they are attracted to strong-smelling substances, some of which are not even edible. For example, antifreeze attracts bears – and is fatal when ingested. The many chemicals in dumps become toxic potions, which either <a href="https://doi.org/10.1139/z85-340">kill bears outright or weaken their immune systems</a>. Additionally, bears have been known to ingest nonfoods. Wood, plastics and metal have all been found in dead bears’ stomachs. Wraps, bags and other membranelike items <a href="https://doi.org/10.1139/z85-340">jam up the small opening from the bear’s stomach to its intestine</a>, resulting in a slow and painful death.</p>
<p>Once bears have thoroughly rummaged through dumps, they spin off into nearby villages – confronting people, attacking their pets and livestock and foraging around structures, within which they expect to find food. </p>
<p>Solutions already exist to remedy this situation. However, they require money and political will. </p>
<p>Electric fencing is highly effective at separating bears from garbage <a href="https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1029&context=icwdmhandbook">but can be costly for a small village</a>. Warehousing garbage, then barging it offsite to facilities where it can be safely disposed of, is also effective, but expensive. <a href="https://doi.org/10.1016/j.gecco.2020.e01320">Incinerators have been used </a> in some villages like Churchill, Canada, and have greatly reduced the amount of garbage. But these solutions come at an even greater cost, so villages would need financial assistance to put them in place. Education about how to properly store bear-attracting foods and substances would also help address the problem. </p>
<p>In brown and black bear battlegrounds like Yellowstone and Yosemite, managers have long fought the problem of bears attracted by garbage, learned and succeeded. From a high of 1,584 human-bear incidents in 1998, <a href="https://doi.org/10.26077/vm5g-7q38">Yosemite recorded only 22 by the end of 2018 – a 99% decrease</a>. </p>
<p>The knowledge exists on how to put an end to “dump bears” – and all that goes with that unfortunate title. In the battle of bears and garbage, bears are most often the losers.</p><img src="https://counter.theconversation.com/content/183968/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tom Smith and the other authors have received, and receive, funding through their respective private, state and federal institutions in order to conduct past and present polar bear research. They have not personally benefited from these funds other than to cover the costs of research. None of these authors benefits in any way from the content of this article. </span></em></p>
Polar bears are increasingly seeking sustenance in human trash because of melting sea ice and a loss of hunting opportunities. The result is a rise in human-bear conflict – and dead bears.
Thomas Scott Smith, Professor - Wildlife and Wildlands Conservation Program, Brigham Young University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/185462
2022-06-22T12:57:18Z
2022-06-22T12:57:18Z
Borgen is back – what the series gets right (and wrong) about Danish politics
<figure><img src="https://images.theconversation.com/files/470033/original/file-20220621-3417-90u6do.jpg?ixlib=rb-1.1.0&rect=152%2C50%2C4048%2C2336&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Danish political drama Borgen has returned to screens after a ten year hiatus.</span> <span class="attribution"><a class="source" href="https://media.netflix.com/en/only-on-netflix/81282868/assets/eyJpZCI6ImZrcTJibGNrd2giLCJuYW1lIjoiX0RTQzIzNjMuanBnIn0=">Mike Kollöffel / Netflix</a></span></figcaption></figure><p>The political drama Borgen first aired in Denmark in 2010. It soon became clear that its creator, Adam Price, had an uncanny ability to predict and, at times, influence political events in the real Christiansborg Palace, the seat of Danish parliament. Borgen began with centrist politician Birgitte Nyborg becoming Denmark’s first female prime minister. This feat was “repeated” a year later in real life by Social Democrat Helle Thorning-Schmidt. </p>
<p>Airing in the Sunday primetime slot just before the news, it was sometimes difficult to tell fiction from political reporting. Episodes dealt with issues such as <a href="https://cphpost.dk/?p=8936">prostitution</a> or <a href="https://www.bt.dk/danmark/virkeligheden-bag-borgen-saadan-behandler-vi-grise-i-danmark">industrialised pig farming</a> that went on to become hot topics in politics and the press.</p>
<p>Almost ten years after the third series ended, the show is back for a fourth. Borgen: Power & Glory follows a now middle-aged Nyborg, a workaholic and principled minister of foreign affairs in a coalition government led by PM and Labour leader Signe Kragh. Kragh’s flair for down-to-earth Instagram snaps of food and sporting events will remind Danish viewers of the <a href="https://www.instagram.com/p/CKq0k0YgfBt/?utm_source=ig_embed&ig_rid=4ebca6b3-2e1c-46ad-b3ec-fb5012ace4e5">current Social Democrat PM Mette Frederiksen</a>.</p>
<p>Price has maintained some of his predictive ability. In the first episode, Nyborg mentions the sanctioning of a Russian oligarch over the recent invasion of Ukraine. Most likely written with the 2014 annexation of Crimea in mind, viewers should be excused for believing that Borgen is entangled in a geopolitical present. A week after it aired in Denmark, Russia invaded Ukraine.</p>
<p>The new season has one major narrative arc: oil has been discovered in Greenland. The seasoned Nyborg rightly predicts trouble when geopolitical superpowers Russia, China and the US rush to assert themselves in the Arctic. Economic interests threaten to trump her party’s environmental ideals, and the already tense relationship between Greenland and Denmark threatens to erupt in a bitter struggle over political power and profits from oil extraction.</p>
<p>One of Borgen’s strengths lies in its portrayal of the increasingly tense geopolitical reality in the Arctic. Denmark and Greenland are both small players dependent upon larger powers. </p>
<figure class="align-center ">
<img alt="The ornate main entrance to Christiansborg with two Rococo pavilions on either side, against a pale blue morning sky in Copenhagen" src="https://images.theconversation.com/files/470029/original/file-20220621-19-lguur2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/470029/original/file-20220621-19-lguur2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/470029/original/file-20220621-19-lguur2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/470029/original/file-20220621-19-lguur2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/470029/original/file-20220621-19-lguur2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/470029/original/file-20220621-19-lguur2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/470029/original/file-20220621-19-lguur2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The real ‘Borgen’. How much do the events inside Christiansborg Palace reflect the Danish political drama?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/main-entrance-christiansborg-two-rococo-pavilions-1173561355">kavalenkava / Shutterstock</a></span>
</figcaption>
</figure>
<p>It also depicts the unequal impacts of climate change. While colonial powers’ oil extractions have driven climate change for centuries, Indigenous people such as the Greenlandic Inuit are <a href="https://www.un.org/en/chronicle/article/climate-change-arctic-inuit-reality">witnessing the effects</a> on their vulnerable ecosystems. This reality opens old wounds in the Danish realm that includes the former colonies and current dependencies of Greenland and the Faroe Islands. </p>
<h2>Colonialism continues on screen</h2>
<p>Denmark colonised Greenland in the 18th century, nearly <a href="https://visitgreenland.com/american-interest-in-greenland/">losing the country</a> to the US during the second world war. In 1953, Denmark initiated a <a href="https://nordics.info/show/artikel/podcast-the-danish-decolonisation-of-greenland-1945-54">“decolonisation”</a> of the country by integrating Greenland as an equal part of Denmark. Greenlanders’ desire for independence led to the introduction of home rule in 1979, and 30 years later Greenland achieved <a href="https://english.stm.dk/the-prime-ministers-office/the-unity-of-the-realm/greenland/">self-rule</a>. Today, the Greenlandic people’s right to self-determination is recognised, and most policies, apart from foreign affairs, are decided in Greenland. However, the abuses of colonial rule throughout Greenland’s modern history have led to <a href="https://sciencenordic.com/denmark-greenland-science-special-society/despite-self-governing-inuit-still-suffer-social-and-health-problems/1434945">social problems</a> such as alcoholism, sexual abuse and unemployment becoming endemic.</p>
<p>Borgen has never shied away from showing the darker sides of the colonial relationship between Denmark and Greenland. In the first season, Nyborg meets with Greenland PM Jens Enok to resolve the case of secret US flight landings with terrorist prisoners in Greenland. Enok reminds her that the issue started 300 years ago when Denmark colonised Greenland, and 60 years ago when Denmark forcefully removed the Inuit to make space for the American airbase. Nyborg initially dismisses Danish colonial guilt by suggesting that the Greenlanders are just “sitting around waiting for the ice to thaw so they can strike oil and get rich”. But Enok makes her realise that Denmark has played a substantial role in Greenland’s ongoing suffering.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/pmRJiZ4mFQU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>In the fourth season, oil is finally struck – and little has changed in Nyborg’s mind. She bullies a Greenlandic delegation, arguing that they cannot be trusted to run their own country. Jens Enok, now a Greenlandic MP, enters again to explain Greenland’s desire to pursue oil extraction. He argues that Greenlanders are the victims of climate change, not its perpetrators. As such, Denmark should not stand in the way of their desire to enrich themselves and achieve full independence. </p>
<h2>Greenlanders choose the environment</h2>
<p>Contrary to the plot of Borgen, today’s Greenlanders prioritise environmentally sustainable development on the road to full independence. In 2021, Greenland’s new government was elected on the promise to <a href="https://overthecircle.com/2021/08/02/turning-off-the-taps-greenland-says-no-to-oil-development-plans/">stop a controversial Uranium</a> and rare-earth mining project in Kuannersuit (Kvanefjeldet) in southern Greenland. The same government also put a stop to further oil exploration for environmental reasons. </p>
<p>It has also become near impossible to stay blind, as Nyborg does, to the colonial abuses perpetrated by the Danish state against Greenlanders. Earlier this year, the Danish PM publicly apologised on behalf of Denmark to 22 Greenlandic <a href="https://www.bbc.co.uk/news/world-europe-60646898">“children of the experiment”</a>. They had been taken from their families in the 1950s and sent to Denmark to be trained as a future Greenlandic elite. </p>
<p>In June 2022, the <a href="https://polarjournal.ch/en/2022/05/13/denmark-had-an-involuntary-iud-programme-in-greenland/">abuse of 4,000 Greenlandic women</a> as young as 13 by Danish health authorities, who implanted intrauterine devices without consent in the 1960s and 1970s, was revealed. In response, the Danish and Greenlandic governments have agreed <a href="https://www.rcinet.ca/eye-on-the-arctic/2022/06/09/greenland-denmark-initiate-investigation-into-past-relations/">to set up a commission</a> to shed light on the historical relationship between the two countries.</p>
<p>As Borgen would be the first fictional television series to tell you, there is still a need for courageous politicians to deliver on environmental sustainability – and investigative journalism to hold them to account – and uncomfortable but necessary confrontations with colonial pasts. Borgen provides the drama and stays close to life, but should not be expected to always get its predictions right.</p><img src="https://counter.theconversation.com/content/185462/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jakob Stougaard-Nielsen does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The Danish drama has become popular around the globe.
Jakob Stougaard-Nielsen, Professor in Scandinavian and Comparative Literature, UCL
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/184787
2022-06-16T12:42:27Z
2022-06-16T12:42:27Z
How Iceberg Alley got its name and why it may be under threat
<figure><img src="https://images.theconversation.com/files/468819/original/file-20220614-26-e9f42t.jpg?ixlib=rb-1.1.0&rect=26%2C26%2C3567%2C2338&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A large iceberg passes near Ferryland, an hour south of St. John's, Nfld., in April 2017</span> <span class="attribution"><span class="source">THE CANADIAN PRESS/Paul Daly</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/how-iceberg-alley-got-its-name-and-why-it-may-be-under-threat" width="100%" height="400"></iframe>
<p>Iceberg Alley, the stretch of coast ranging from Labrador to Newfoundland, is the southernmost region of the northern hemisphere where one can regularly see icebergs. But hurry up! As the planet continues to warm, Iceberg Alley may soon lose its name.</p>
<p>Iceberg sightseeing is a common — and much-anticipated — activity in Newfoundland. Every spring, locals and visitors brave the region’s damp and chilly weather — it’s one of the <a href="http://doi.org/10.1007/978-3-319-45229-6_2">foggiest places on the planet</a> — to scrutinize the horizon for large white objects or embark on boat tours, hoping that luck will be on their side. </p>
<p>But with iceberg counts ranging from <a href="https://doi.org/10.20383/101.0301">zero to more than 2,000</a> per year, booking a trip in advance to see these 10,000-year-old blocks of ice can be a gamble. </p>
<h2>10,000-year-old ice</h2>
<p>Every year, <a href="https://doi.org/10.1002/2013GL059010">hundreds of billions of tonnes of ice</a>, equivalent to more than 100 million Olympic pools of water, once melted, is shed from Greenland’s glaciers into the ocean. This phenomenon is called calving. </p>
<p>The bulk of the ice calving from Greenland’s glaciers form icebergs. While about <a href="https://doi.org/10.1002/2016GL070718">10-50 per cent</a> of these icebergs melt directly in Greenland’s fjords, the majority are carried away by ocean currents.</p>
<figure class="align-right ">
<img alt="A map of the North Atlantic Ocean showing the flow of icebergs from Greenland to the coast of Newfoundland." src="https://images.theconversation.com/files/468815/original/file-20220614-21-u1jaic.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/468815/original/file-20220614-21-u1jaic.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=775&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468815/original/file-20220614-21-u1jaic.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=775&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468815/original/file-20220614-21-u1jaic.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=775&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468815/original/file-20220614-21-u1jaic.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=974&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468815/original/file-20220614-21-u1jaic.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=974&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468815/original/file-20220614-21-u1jaic.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=974&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The icebergs that arrive in Newfoundland calve from the west coast of Greenland and follow ocean currents to the south. Data: General Bathymetric Chart of the Oceans.</span>
<span class="attribution"><a class="source" href="https://www.gebco.net/data_and_products/gridded_bathymetry_data/version_20141103/">(Frédéric Cyr)</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The Greenland ice sheet is the result of <a href="https://doi.org/10.1016/j.quascirev.2010.02.007">thousands of years of snow accumulation</a> that has reached a thickness of more than one kilometre. The pressure that comes from the enormous weight transforms the snow into ice. The same pressure pushes the glaciers — rivers of ice funnelled by numerous fjords — towards the ocean where they calve and form icebergs. </p>
<p>A subset of these icebergs, mostly originating from the west coast of Greenland, will reach Newfoundland. While these icebergs can live for as long as a decade, those reaching Newfoundland are generally <a href="https://doi.org/10.1029/2018GL077676">one to two years old</a>.</p>
<h2>Sinking of the Titanic</h2>
<p>The most famous of these icebergs is probably the one that sank the Titanic just south of the tip of the Grand Banks of Newfoundland in 1912. That year was <a href="https://theconversation.com/titanic-twist-1912-wasnt-a-bad-year-for-icebergs-after-all-25621">not an abnormal one for icebergs</a>, with 1,038 icebergs reported. Following this tragedy, in 1913, the <a href="https://www.mycg.uscg.mil/News/Article/3028040/international-ice-patrol-11-decades-of-monitoring-the-northern-atlantic-waters/">International Ice Patrol</a>, operated by the U.S. Coast Guard on behalf of several maritime nations, was created to monitor iceberg dangers for ships in the North Atlantic.</p>
<p>The International Ice Patrol’s <a href="https://nsidc.org/data/G10028">annual count of the number of icebergs that slip south of 48 degrees north</a> provides the longest and most reliable time series of icebergs in Newfoundland. In an average year, nearly <a href="https://doi.org/10.20383/101.0301">800 icebergs</a> are expected to cross the boundary, which lies just north of the Grand Banks of Newfoundland.</p>
<figure class="align-center ">
<img alt="Graphic showing the high variability in the number of observed icebergs over the past 122 years." src="https://images.theconversation.com/files/468842/original/file-20220614-8082-bt1kez.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468842/original/file-20220614-8082-bt1kez.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=285&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468842/original/file-20220614-8082-bt1kez.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=285&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468842/original/file-20220614-8082-bt1kez.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=285&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468842/original/file-20220614-8082-bt1kez.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=359&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468842/original/file-20220614-8082-bt1kez.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=359&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468842/original/file-20220614-8082-bt1kez.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=359&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Number of icebergs observed, 1900-2021.</span>
<span class="attribution"><span class="source">(Frédéric Cyr)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>These annual counts are extremely variable and affected by the climate of the North Atlantic. The 1980s and ‘90s were an especially cold period in the region, and more than 1,500 icebergs were observed during some of those years, with a record high of 2,202 in 1984. More recently, 1,515 icebergs were spotted in 2019, a year characterized with <a href="https://www.dfo-mpo.gc.ca/csas-sccs/Publications/ResDocs-DocRech/2021/2021_017-eng.html">colder than normal spring temperatures</a> and immediately following another cold period in the mid-2010s.</p>
<p>But these numbers decrease drastically during years characterized by milder winters and an early spring. This occurred in 2010 and 2021, where only one iceberg was observed; in 2011, which saw two icebergs; and in 2013, where 13 icebergs were recorded. Only two years, 1966 and 2006, in the 122-year time series have reported no icebergs journeying south of 48 degrees north.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/titanic-twist-1912-wasnt-a-bad-year-for-icebergs-after-all-25621">Titanic twist: 1912 wasn’t a bad year for icebergs after all</a>
</strong>
</em>
</p>
<hr>
<h2>An uncertain future</h2>
<p>With the planet warming up as a result of anthropogenic climate change, the <a href="https://doi.org/10.1038/s41586-019-1855-2">Greenland ice sheet is losing mass</a>. While this may suggest that more icebergs will calve into the ocean, it is far from guaranteed that this will lead to more sightseeing opportunities in Newfoundland. And the numbers may lie, as improvements in iceberg-detecting technology may be responsible for an <a href="https://www.navcen.uscg.gov/sites/default/files/pdf/iip/2018_Annual_Report_FINAL.pdf">apparent upward trend in counts</a>.</p>
<figure class="align-center ">
<img alt="An aerial view of a glacier with large and small chunks of ice floating in the water at its foot, with rocky slopes on either side of the narrow fjord." src="https://images.theconversation.com/files/468822/original/file-20220614-15-33xmz6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468822/original/file-20220614-15-33xmz6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468822/original/file-20220614-15-33xmz6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468822/original/file-20220614-15-33xmz6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468822/original/file-20220614-15-33xmz6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468822/original/file-20220614-15-33xmz6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468822/original/file-20220614-15-33xmz6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A glacier calves icebergs into a fjord off the Greenland ice sheet in southeastern Greenland in August 2017.</span>
<span class="attribution"><span class="source">(AP Photo/David Goldman)</span></span>
</figcaption>
</figure>
<p>The environmental parameters that control the number of icebergs in Newfoundland in a given year remain unclear. However, it appears that a warmer climate definitely leads to fewer or simply no icebergs at all in Newfoundland. </p>
<p>For example, when looking at the region’s three warmest years on record — 1966, 2010 and 2021 — only <a href="https://www.dfo-mpo.gc.ca/csas-sccs/Publications/ResDocs-DocRech/2022/2022_040-eng.html">zero, one and one icebergs</a> were reported. These outliers may well become the new norm as climate projections suggest with a high level of confidence that the <a href="https://www.ipcc.ch/report/ar6/wg2/">frequency and severity of extreme events</a>, such as an anomalously warm year, will increase in the future.</p>
<p>While the Newfoundland iceberg sightseeing tourism industry may well have benefited from a succession of exceptional iceberg seasons linked to a recent rebound in cold ocean conditions in the mid-2010s, its future is less certain. </p>
<p>Will the Iceberg Alley lose its name? It would be unfortunate, but it is possible. For the moment there is still time to enjoy these 10,000-year-old remnants of the past. So hurry up before it’s too late!</p><img src="https://counter.theconversation.com/content/184787/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frédéric Cyr does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Between zero and 2,000 icebergs reach Newfoundland each spring, but the warming climate could see an end to Iceberg Alley.
Frédéric Cyr, Adjunct professor, Physical Oceanography, Memorial University of Newfoundland
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/172136
2021-12-14T16:45:01Z
2021-12-14T16:45:01Z
2021 Arctic Report Card reveals a (human) story of cascading disruptions, extreme events and global connections
<figure><img src="https://images.theconversation.com/files/436805/original/file-20211209-188518-u3cogf.jpg?ixlib=rb-1.1.0&rect=0%2C3%2C2543%2C1686&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Community members from Utqiagvik, Alaska, look to open water from the edge of shorefast sea ice. </span> <span class="attribution"><span class="source">Matthew Druckenmiller</span></span></figcaption></figure><p>The Arctic has long been portrayed as a distant end-of-the-Earth place, disconnected from everyday common experience. But as the planet rapidly warms, what happens in this icy region, where <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/948/Surface-Air-Temperature">temperatures are rising twice as fast as the rest of the globe</a>, increasingly affects lives <a href="https://doi.org/10.1029/2018EF001088">around the world</a>.</p>
<p>On Dec. 14, 2021, a team of 111 scientists from 12 countries released the 16th annual <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021">Arctic Report Card</a>, a yearly update on the state of the Arctic system. <a href="https://cires.colorado.edu/researcher/matthew-druckenmiller">We are</a> <a href="https://cires.colorado.edu/researcher/twila-moon">Arctic</a> <a href="https://news.uaf.edu/expertsguide/rick-thoman">scientists</a> and the editors of this peer-reviewed assessment. In the report, we take a diverse look across the region’s interconnected physical, ecological and human components. </p>
<p>Like an annual checkup with a physician, the report assesses the Arctic’s vital signs – including <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/948/Surface-Air-Temperature">surface air temperatures</a>, <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/944/Sea-Surface-Temperature">sea surface temperatures</a>, <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/945/Sea-Ice">sea ice</a>, <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/947/Terrestrial-Snow-Cover">snow cover</a>, <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/946/Greenland-Ice-Sheet">the Greenland ice sheet</a>, <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/936/Tundra-Greenness">greening of the tundra</a>, and <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/937/Arctic-Ocean-Primary-Productivity-The-Response-of-Marine-Algae-to-Climate-Warming-and-Sea-Ice-Decline">photosynthesis rates by ocean algae</a> – while inquiring into other indicators of health and emerging factors that shed light on the trajectory of Arctic changes. </p>
<p>As the report describes, rapid and pronounced human-caused warming continues to drive most of the changes, and ultimately is paving the way for disruptions that affect ecosystems and communities far and wide.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_WbWjLUTvZM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A closer look at the 2021 Arctic Report Card.</span></figcaption>
</figure>
<h2>Continued loss of ice</h2>
<p>Arctic Sea ice – a central vital sign and one of the most iconic indicators of global climate change – <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/945/Sea-Ice">is continuing to shrink</a> under warming temperatures. </p>
<p>Including data from 2021, 15 of the lowest summer sea ice extents – the point when the ice is at its minimum reach for the year – <a href="https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/">have all occurred in the last 15 years</a>, within a record dating back to 1979 when satellites began regularly monitoring the region.</p>
<p>The sea ice is also thinning at an alarming rate as the Arctic’s oldest and thickest multi-year ice disappears. This loss of sea ice diminishes the Arctic’s ability to cool the global climate. It can also <a href="https://doi.org/10.1080/15230430.2021.1942400">alter lower latitude weather systems</a> to an extent that makes previously rare and impactful weather events, like droughts, heat waves and extreme winter storms, more likely.</p>
<p>Similarly, the <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/946/Greenland-Ice-Sheet">persistent melting of the Greenland ice sheet</a> and other land-based ice is raising seas worldwide, exacerbating the severity and exposure to coastal flooding, disruptions to drinking and waste water systems, and coastal erosion for more communities around the planet. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/436435/original/file-20211208-23-p9y7vr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436435/original/file-20211208-23-p9y7vr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436435/original/file-20211208-23-p9y7vr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436435/original/file-20211208-23-p9y7vr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436435/original/file-20211208-23-p9y7vr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=462&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436435/original/file-20211208-23-p9y7vr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=462&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436435/original/file-20211208-23-p9y7vr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=462&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">NOAA Climate.gov/NSIDC</span></span>
</figcaption>
</figure>
<h2>A warmer, wetter Arctic</h2>
<p>This transition from ice to water and its effects are evident across the Arctic system. </p>
<p>The eight major Arctic rivers are <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/953/River-Discharge">discharging more freshwater</a> into the Arctic Ocean, reflecting an Arctic-wide increase in water coming from land as a result of precipitation, permafrost thaw and ice melt. Remarkably, the summit of the Greenland ice sheet – over 10,000 feet above sea level – experienced its <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/946/Greenland-Ice-Sheet">first-ever observed rainfall during summer 2021</a>. </p>
<p>These developments point to a changed and more variable Arctic today. They also give credence to <a href="https://doi.org/10.1038/s41467-021-27031-y">new modeling studies</a> that show the potential for the Arctic to transition from a snow-dominated to rain-dominated system in summer and autumn by the time global temperatures rise to only 1.5 degrees Celisus (2.7 F) above pre-industrial times. The world has <a href="https://public.wmo.int/en/media/press-release/2020-was-one-of-three-warmest-years-record">already warmed by 1.2 C (2.2 F)</a>.</p>
<p>Such a shift to more rain and less snow would further transform landscapes, fueling faster glacier retreat and permafrost loss. The thaw of permafrost not only affects ecosystems but also further <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2019/ArtMID/7916/ArticleID/844/Permafrost-and-the-Global-Carbon-Cycle">adds to climate warming</a> by allowing previously once-frozen plant and animal remains to decompose, releasing additional greenhouse gases to the atmosphere.</p>
<p>This year’s report highlights how retreating glaciers and deteriorating permafrost are also posing growing <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/951/Glacier-and-Permafrost-Hazards">threats to human life through abrupt and localized flooding and landslides</a>. It urges coordinated international efforts to identify these hazards. More rain in the Arctic will further multiply these threats.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/436436/original/file-20211208-19-1k9eode.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436436/original/file-20211208-19-1k9eode.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=610&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436436/original/file-20211208-19-1k9eode.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=610&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436436/original/file-20211208-19-1k9eode.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=610&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436436/original/file-20211208-19-1k9eode.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=766&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436436/original/file-20211208-19-1k9eode.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=766&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436436/original/file-20211208-19-1k9eode.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=766&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">NOAA Climate.gov/CS ERA5</span></span>
</figcaption>
</figure>
<h2>Rising human impact</h2>
<p>Observed changes and disruptions in the Arctic have bearing on everyday lives and actions worldwide, either directly or as stark reminders of a range of human-caused harm to climate and ecosystems. </p>
<p>An Arctic Report Card essay on <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/955/Beaver-Engineering-Tracking-a-New-Disturbance-in-the-Arctic">beavers expanding northward into Arctic tundra</a> to exploit newly favorable conditions is a case study for how species around the world are on the move as habitats respond to climate shifts, and the need for new forms of collaborative monitoring to assess the scale of the resulting ecological transformations. </p>
<p>An essay on <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/952/2020-Foreign-Marine-Debris-Event%e2%80%94Bering-Strait">marine garbage from shipping washing ashore on the Bering Sea coast</a>, posing an immediate threat to food security in the region, reminds us that the threat of both micro- and macro-plastics in our oceans is a <a href="https://doi.org/10.17226/26132">preeminent challenge of our time</a>.</p>
<p>A report on <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/950/The-Changing-Arctic-Marine-Soundscape">shipping noise increasingly infiltrating the Arctic’s underwater marine soundscape</a>, to the detriment of marine mammals, is a call to conserve the integrity of natural soundscapes worldwide. For example, a <a href="https://doi.org/10.1038/s41467-021-26488-1">recent unrelated study</a> found that noise caused by human activities and biodiversity loss are deteriorating the spring songbird soundscapes in North America and Europe. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/436787/original/file-20211209-141213-12ddc9u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436787/original/file-20211209-141213-12ddc9u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436787/original/file-20211209-141213-12ddc9u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436787/original/file-20211209-141213-12ddc9u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436787/original/file-20211209-141213-12ddc9u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436787/original/file-20211209-141213-12ddc9u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436787/original/file-20211209-141213-12ddc9u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Donna Erickson cuts fish at camp near Unalakleet, Alaska.</span>
<span class="attribution"><span class="source">Jeff Erickson</span></span>
</figcaption>
</figure>
<p>Yet, an <a href="https://arctic.noaa.gov/Report-Card/Report-Card-2021/ArtMID/8022/ArticleID/957/The-Impact-of-COVID-19-on-Food-Access-for-Alaska-Natives-in-2020">Arctic Report Card essay from members of the Indigenous Foods Knowledges Network</a> highlights how, despite the continued climate threats to Arctic food systems, Alaska Indigenous communities weathered early pandemic disruptions to food security through their cultural values for sharing and “community-first” approaches.</p>
<p>Their cooperation and ability to adapt offer an important lesson for similarly struggling communities worldwide, while reminding everyone that the Arctic itself is a homeland; a place where large-scale disruptions are not new to its over 1 million Indigenous Peoples, and where solutions have long been found in practices of reciprocity.</p>
<h2>An Arctic connected to the rest of the world</h2>
<p>The Arctic Report Card compiles observations from across the circumpolar North, analyzing them within a polar projection of our planet. This puts the Arctic at the center, with all meridians extending outward to the rest of the world. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/436816/original/file-20211209-149721-mt0if2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/436816/original/file-20211209-149721-mt0if2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436816/original/file-20211209-149721-mt0if2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436816/original/file-20211209-149721-mt0if2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436816/original/file-20211209-149721-mt0if2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436816/original/file-20211209-149721-mt0if2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436816/original/file-20211209-149721-mt0if2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436816/original/file-20211209-149721-mt0if2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some of the Arctic events of 2021 discussed in the Arctic Report Card.</span>
<span class="attribution"><span class="source">NOAA Climate.gov</span></span>
</figcaption>
</figure>
<p>In this view, the Arctic is tethered to societies worldwide through a myriad of exchanges – the natural circulation of air, ocean and contaminants, the migration of animals and invasive species, as well as human-driven transport of people, pollution, goods and natural resources. The warming of the Arctic is also allowing for <a href="https://www.pame.is/projects-new/arctic-shipping/pame-shipping-highlights/411-arctic-shipping-status-reports">greater marine access</a> as sea ice loss permits ships to move deeper into Arctic waters and for longer periods of time. </p>
<p>[<em>Over 140,000 readers rely on The Conversation’s newsletters to understand the world.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-140ksignup">Sign up today</a>.]</p>
<p>These realities illuminate the importance for increased international cooperation in conservation, hazard mitigation and scientific research.</p>
<p>The Arctic has already undergone unprecedented rapid environmental and social changes. A warmer and more accessible Arctic results in a world only tethered more tightly together.</p><img src="https://counter.theconversation.com/content/172136/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew Druckenmiller receives funding from the National Oceanic and Atmospheric Administration (NOAA) to serve as a scientific editor of the Arctic Report Card. </span></em></p><p class="fine-print"><em><span>Rick Thoman receives funding from the National Oceanic and Atmospheric Administration (NOAA) via Cooperative Institute for Climate, Ocean, and Ecosystem Studies (CICOES) to serve as a scientific editor of the Arctic Report Card. </span></em></p><p class="fine-print"><em><span>Twila Moon receives funding from the National Oceanic and Atmospheric Administration (NOAA) to serve as a scientific editor for the Arctic Report Card. </span></em></p>
Sea ice is thinning at an alarming rate. Snow is shifting to rain. And humans worldwide are increasingly feeling the impact of what happens in the seemingly distant Arctic.
Matthew L. Druckenmiller, Research Scientist, National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder
Rick Thoman, Alaska Climate Specialist, University of Alaska Fairbanks
Twila A. Moon, Deputy Lead Scientist, National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/166567
2021-08-25T03:03:03Z
2021-08-25T03:03:03Z
What Greenland’s record-breaking rain means for the planet
<p>For three days this month, <a href="https://nsidc.org/greenland-today/2021/08/rain-at-the-summit-of-greenland/">7 billion tonnes of rain</a> fell across Greenland — the largest amount since records began in 1950. It’s also the first time since then that rain, not snow, fell on Greenland’s highest peak. </p>
<p>This is alarming. Greenland’s ice sheet is the second largest on the planet (after Antarctica) and any rain falling on its surface accelerates melting. By August 15, the amount of ice lost was seven times greater than is normal for mid-August.</p>
<p>This is just the latest extreme climate event on the island, which sits in the North Atlantic Ocean. In <a href="https://www.theguardian.com/environment/2021/jul/30/greenland-ice-sheet-florida-water-climate-crisis">a single day</a> in July this year, the amount of ice that melted in Greenland would have covered the US state of Florida with 5 centimetres of water. And last October, <a href="https://www.nature.com/articles/s41586-020-2742-6">research showed</a> ice in Greenland is melting faster than at any other time in the past 12,000 years.</p>
<p>Melting in Greenland threatens to significantly hamper humanity’s efforts to mitigate climate change. That’s because, after a certain point, it may create catastrophic “feedback loops”. Let’s look at the issue in more detail.</p>
<h2>Rising temperatures in the Arctic</h2>
<p>Greenland’s vast <a href="https://nsidc.org/cryosphere/quickfacts/icesheets.html">ice sheet</a> comprises almost 1.7 million square kilometres of glacial land ice. It covers most of the territory and contains enough ice to raise sea levels by more than <a href="https://advances.sciencemag.org/content/5/6/eaav9396">7 metres</a> if melted. </p>
<p>The Greenland and Antarctica ice sheets lost a <a href="https://www.esa.int/Applications/Observing_the_Earth/Space_for_our_climate/Greenland_and_Antarctica_losing_ice_six_times_faster_than_expected">combined 6.4 trillion tonnes of ice</a> between 1992 and 2017. Melting in Greenland has <a href="https://climate.nasa.gov/news/2958/greenland-antarctica-melting-six-times-faster-than-in-the-1990s/">contributed to 60%</a> (17.8 millimetres) of the Earth’s overall sea-level rise due to melting ice sheets, even though Greenland is much smaller than Antarctica. </p>
<p>This may be partly because half of Greenland’s melting is the <a href="https://www.esa.int/Applications/Observing_the_Earth/Space_for_our_climate/Greenland_and_Antarctica_losing_ice_six_times_faster_than_expected">result of rising air temperatures</a>, which cause surface melting. In Antarctica, most ice loss is from ocean water melting glaciers that spill from land into the sea. And the rate of ice loss in both Greenland and Antarctica <a href="https://www.nature.com/articles/d41586-019-03595-0">is accelerating</a> — increasing sixfold since the 1990s.</p>
<p>Rain falling on ice exacerbates this process. So what’s behind the recent unprecedented weather?</p>
<p>Temperatures in the Arctic are <a href="https://theconversation.com/climate-explained-why-is-the-arctic-warming-faster-than-other-parts-of-the-world-160614">rising twice as quickly</a> as the rest of the planet for a number of reasons, <a href="https://www.nasa.gov/topics/earth/features/warmingpoles.html">including</a> changes in cloud cover and water vapour, the reflectivity of the surface, and how weather systems transport energy from the tropics to the polar regions. This has made extreme weather events more common.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-explained-why-is-the-arctic-warming-faster-than-other-parts-of-the-world-160614">Climate explained: why is the Arctic warming faster than other parts of the world?</a>
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</em>
</p>
<hr>
<p>In recent years in Greenland, rain has fallen further north, and more rain has fallen in winter. This is not normal for these regions, which usually get snow, not rain, in below-freezing temperatures.</p>
<p>This month’s rain is <a href="https://nsidc.org/greenland-today/2021/08/rain-at-the-summit-of-greenland/">the result of</a> warm, moist air flowing up from south-west of Greenland and remaining for several days. In the morning of August 14, temperatures at the 3,216-metre summit of Greenland’s ice sheet surpassed freezing point, peaking at 0.48°C. Rain fell on the summit for several hours that morning and on August 15. </p>
<p>This was <a href="https://www.npr.org/2021/08/20/1029633740/rain-fall-peak-of-greenland-ice-sheet-first-climate-change">particularly shocking</a> given the above-freezing temperatures occurred so late in Greenland’s normally short summer. At this time of year, large areas of bare ice are exposed from a lack of snow, which leads to greater runoff of rainwater and meltwater into the oceans.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/417529/original/file-20210824-21-641ihm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/417529/original/file-20210824-21-641ihm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/417529/original/file-20210824-21-641ihm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/417529/original/file-20210824-21-641ihm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/417529/original/file-20210824-21-641ihm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/417529/original/file-20210824-21-641ihm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/417529/original/file-20210824-21-641ihm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/417529/original/file-20210824-21-641ihm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Temperatures rarely surpass freezing at Greenland’s highest point.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>When melting is self-reinforcing</h2>
<p>Rainfall makes the ice sheet more prone to surface melt since it exacerbates the so-called “ice-albedo positive feedback”. In other words, the melting reinforces itself. </p>
<p>When rain falls, its warmth can melt snow, exposing the underlying darker ice, which absorbs more sunlight. This increases temperatures at the surface, leading to more melting.</p>
<p>Unfortunately, this isn’t the only <a href="https://www.pnas.org/content/118/21/e2024192118">positive feedback loop</a> destabilising the Greenland ice sheet. </p>
<p>The “positive melt-elevation feedback” is another, where the lower height of the ice sheet leads to faster melting because higher temperatures occur at lower altitudes. </p>
<p>Also worrying is when higher temperatures cause coastal glaciers to thin, allowing <a href="https://advances.sciencemag.org/content/5/6/eaav9396">more ice to slip into the sea</a>. This both speeds up the rate of glacier flow towards the sea and lowers the ice surface, exposing it to warmer air temperatures and, in turn, increasing melting.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/417527/original/file-20210824-17-drt768.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/417527/original/file-20210824-17-drt768.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/417527/original/file-20210824-17-drt768.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/417527/original/file-20210824-17-drt768.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/417527/original/file-20210824-17-drt768.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/417527/original/file-20210824-17-drt768.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/417527/original/file-20210824-17-drt768.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/417527/original/file-20210824-17-drt768.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The rate of ice loss in both Greenland and Antarctica is accelerating.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What does this mean for the planet?</h2>
<p>These positive feedbacks can lead to tipping points — abrupt and irreversible changes in the climate system after a certain threshold is reached. We are more likely to reach these tipping points as emissions increase and global temperatures rise. </p>
<p>While the science on tipping points is still emerging, the <a href="https://www.ipcc.ch/report/ar6/wg1/">most recent report</a> from the Intergovernmental Panel on Climate Change said <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_TS.pdf">they cannot be ruled out</a>. The report identified likely tipping points such as widespread Arctic sea-ice melting and the thawing of methane-rich permafrost. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/failure-is-not-an-option-after-a-lost-decade-on-climate-action-the-2020s-offer-one-last-chance-158913">'Failure is not an option': after a lost decade on climate action, the 2020s offer one last chance</a>
</strong>
</em>
</p>
<hr>
<p>Recent studies show what humanity may be up against. <a href="https://www.pnas.org/content/118/21/e2024192118">A study from May this year</a> showed a substantial part of the Greenland ice sheet is either at, or about to reach, a tipping point where melting will accelerate, even if global warming is stopped. <a href="https://www.nature.com/articles/d41586-019-03595-0">Scientists are concerned</a> reaching this point may trigger a cascade effect, leading to other tipping points being reached.</p>
<p>Melted ice from both the Arctic Ocean and Greenland have caused an influx of freshwater into the North Atlantic Ocean. This <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/oceans/amoc">has contributed to</a> the slowing of a system of crucial ocean currents, which carry warm water from the tropics into the colder North Atlantic. This current, called the Atlantic Meridional Overturning Circulation (AMOC), has slowed by 15% since the 1950s.</p>
<p>If the AMOC slows down any further, the consequences for the planet could be profound. It could destabilise the West African monsoon, cause more frequent drought in the Amazon rainforest and accelerate ice loss in Antarctica.</p>
<h2>An existential threat</h2>
<p>The rising likelihood of tipping points being reached beyond 1.5°C of warming represents a potential, looming existential threat to human civilisation. However, even if we’ve already crossed some tipping points, as <a href="https://www.theguardian.com/environment/2019/nov/27/climate-emergency-world-may-have-crossed-tipping-points">some scientists suggest</a>, how fast the impacts unfold is still within our control.</p>
<p>If we limit global warming to 1.5°C this century, we give ourselves longer to adapt to heating already locked into the Earth’s system. But the window is rapidly closing; estimates indicate we may reach the crucial 1.5°C threshold <a href="https://www.weforum.org/agenda/2021/08/ipcc-report-on-climate-change/">as soon as the mid-2030s</a>.</p>
<p>The message for humanity is urgent: hard science, not cloying political spin, needs to dictate climate action in the coming years. As with COVID-19, listening to the scientists gives us the best hope of saving the planet.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/when-greenland-was-green-rapid-global-warming-55-million-years-ago-shows-us-what-the-future-may-hold-166342">When Greenland was green: rapid global warming 55 million years ago shows us what the future may hold</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/166567/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Willow Hallgren does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Greenland’s melting ice sheets threaten to significantly hamper humanity’s efforts to mitigate climate change.
Willow Hallgren, Adjunct Research Fellow, Centre for Planetary Health and Food Security, Griffith University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/164138
2021-07-20T12:16:04Z
2021-07-20T12:16:04Z
The US Army tried portable nuclear power at remote bases 60 years ago – it didn’t go well
<figure><img src="https://images.theconversation.com/files/410670/original/file-20210709-23-zyldp6.jpg?ixlib=rb-1.1.0&rect=0%2C404%2C5097%2C5783&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Part of a portable nuclear power plant arrives at Camp Century in 1960.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/the-u-s-army-engineers-who-are-installing-a-portable-news-photo/1180258522?adppopup=true">Bettmann Archive/Getty Images</a></span></figcaption></figure><p>In a tunnel 40 feet beneath the surface of the Greenland ice sheet, a <a href="https://www.west-point.org/class/usma1955/D/Hist/Century.htm">Geiger counter screamed</a>. It was 1964, the height of the Cold War. U.S. soldiers in the tunnel, 800 miles from the North Pole, were dismantling the Army’s first portable nuclear reactor. </p>
<p>Commanding Officer Joseph Franklin grabbed the radiation detector, ordered his men out and did a quick survey before retreating from the reactor. </p>
<p>He had spent about two minutes exposed <a href="https://www.dignitymemorial.com/obituaries/arlington-va/joseph-franklin-7323412">to a radiation field he estimated at 2,000 rads per hour</a>, enough to <a href="https://www.cdc.gov/nceh/radiation/emergencies/arsphysicianfactsheet.htm">make a person ill</a>. When he came home from Greenland, the Army sent Franklin to the Bethesda Naval Hospital. There, <a href="https://www.west-point.org/class/usma1955/D/Hist/Century.htm">he set off</a> a <a href="https://www.osti.gov/includes/opennet/includes/Understanding%20the%20Atom/Whole%20Body%20Counters.pdf">whole body radiation counter</a> designed to assess victims of nuclear accidents. Franklin was radioactive.</p>
<p>The Army called the reactor portable, even at 330 tons, because it was built from pieces that each fit in a C-130 cargo plane. It was powering Camp Century, one of the military’s most unusual bases. </p>
<figure class="align-center ">
<img alt="Three people stand at the opening of a trench with a half-round metal cover" src="https://images.theconversation.com/files/410664/original/file-20210709-15-qcgv1l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410664/original/file-20210709-15-qcgv1l.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=486&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410664/original/file-20210709-15-qcgv1l.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=486&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410664/original/file-20210709-15-qcgv1l.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=486&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410664/original/file-20210709-15-qcgv1l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=610&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410664/original/file-20210709-15-qcgv1l.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=610&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410664/original/file-20210709-15-qcgv1l.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=610&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Camp Century tunnels started as trenches cut into the ice.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/9/96/Camp_Century_trench_construction.png">U.S. Army Corps of Engineers</a></span>
</figcaption>
</figure>
<p>Camp Century was a series of tunnels built into the Greenland ice sheet and used for <a href="https://gombessa.tripod.com/scienceleadstheway/id9.html">both military research and scientific projects</a>. The military boasted that the nuclear reactor there, known as the PM-2A, needed just 44 pounds of uranium to replace a million or more gallons of diesel fuel. Heat from the reactor ran lights and equipment and allowed the 200 or so men at the camp <a href="https://www.youtube.com/watch?v=NnBG37CPDLI">as many hot showers as they wanted</a> in that brutally cold environment. </p>
<p>The PM-2A was the third child in a <a href="https://www.osti.gov/includes/opennet/includes/Understanding%20the%20Atom/Power%20Reactors%20in%20Small%20Packages%20V.2.pdf">family of eight Army reactors</a>, several of them experiments in portable nuclear power. </p>
<p>A few were misfits. PM-3A, nicknamed <a href="https://theconversation.com/remembering-antarcticas-nuclear-past-with-nukey-poo-99934">Nukey Poo</a>, was installed at the Navy base at Antarctica’s McMurdo Sound. It made a <a href="https://books.google.se/books?id=wwoAAAAAMBAJ&lpg=PA32&ots=VkjNgAvyhE&dq=PM-3A+Nukey+Poo&pg=PA32&redir_esc=y#v=onepage&q&f=false">nuclear mess in the Antarctic</a>, with 438 malfunctions in 10 years including a cracked and leaking containment vessel. SL-1, a stationary low-power nuclear reactor in Idaho, blew up during refueling, <a href="https://www.osti.gov/sciencecinema/biblio/1122857">killing three men</a>. SM-1 still sits 12 miles from the White House at Fort Belvoir, Virginia. It cost <a href="http://www.virginiaplaces.org/energy/nuclearbelvoir.html">US$2 million to build</a> and is expected to cost <a href="https://www.nab.usace.army.mil/Media/News-Releases/Article/2328156/army-corps-to-decommission-and-dismantle-historic-deactivated-nuclear-power-pla/">$68 million to clean up</a>. The only truly mobile reactor, <a href="https://digital.library.unt.edu/ark:/67531/metadc100219/m2/1/high_res_d/metadc100219.pdf">the ML-1</a>, <a href="https://atomicinsights.com/ml1-mobile-power-system-reactor-box/">never really worked</a>.</p>
<figure class="align-center ">
<img alt="A truck with a box on a trailer behind it" src="https://images.theconversation.com/files/410448/original/file-20210708-13-16ie7j3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410448/original/file-20210708-13-16ie7j3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=497&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410448/original/file-20210708-13-16ie7j3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=497&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410448/original/file-20210708-13-16ie7j3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=497&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410448/original/file-20210708-13-16ie7j3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=624&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410448/original/file-20210708-13-16ie7j3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=624&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410448/original/file-20210708-13-16ie7j3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=624&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Army abandoned its truck-mounted portable reactor program in 1965. This is the ML-1.</span>
<span class="attribution"><a class="source" href="https://usace.contentdm.oclc.org/digital/collection/p15141coll5/id/4152/rec/19">U.S. Army Corps of Engineers</a></span>
</figcaption>
</figure>
<p>Nearly 60 years after the PM-2A was installed and the <a href="https://www.usace.army.mil/Portals/2/Users/071/27/327/Exhibits/x05%2006%20-%20Experimental%20Reactors.jpg?ver=2019-06-13-150102-913">ML-1 project abandoned</a>, the U.S. military is exploring portable land-based nuclear reactors again. </p>
<p>In May 2021, the Pentagon requested $60 million for <a href="https://www.cto.mil/pele_eis/">Project Pele</a>. Its goal: Design and build, within five years, a small, truck-mounted portable nuclear reactor that could be flown to remote locations and war zones. It would be able to be powered up and down for <a href="https://www.thedrive.com/the-war-zone/40914/the-militarys-mobile-nuclear-reactor-prototype-is-set-to-begin-taking-shape">transport within a few days</a>. </p>
<p>The Navy has a long and mostly successful history of mobile nuclear power. The first two nuclear submarines, the Nautilus and the Skate, <a href="https://www.jstor.org/stable/10.14321/rhetpublaffa.16.3.0521#metadata_info_tab_contents">visited the North Pole in 1958</a>, just before Camp Century was built. Two other nuclear submarines sank in the 1960s – their reactors sit quietly on the Atlantic Ocean floor <a href="https://www.energy.gov/sites/prod/files/2019/09/f66/NT-19-1.pdf">along with two plutonium-containing nuclear torpedos</a>. Portable reactors on land pose different challenges – any problems are not under thousands of feet of ocean water.</p>
<p>Those in <a href="https://www.defense.gov/Newsroom/Releases/Release/Article/2545869/strategic-capabilities-office-selects-two-mobile-microreactor-concepts-to-proce/">favor of mobile nuclear power</a> for the battlefield claim it will provide nearly unlimited, low-carbon energy without the need for vulnerable supply convoys. Others argue that the <a href="https://sites.utexas.edu/nppp/files/2021/04/Army-Reactor-Report-NPPP-2021-April.pdf">costs and risks</a> outweigh the benefits. There are also concerns about <a href="https://thebulletin.org/2020/06/small-military-nuclear-reactors-in-need-of-global-safeguards/">nuclear proliferation</a> if mobile reactors are able to avoid international inspection. </p>
<h2>A leaking reactor on the Greenland ice sheet</h2>
<p>The PM-2A was built in 18 months. It arrived at Thule Air Force Base in Greenland in July 1960 and was dragged 138 miles across the ice sheet in pieces and <a href="https://usace.contentdm.oclc.org/digital/collection/p266001coll1/id/3968/">then assembled</a> at Camp Century.</p>
<p>When the reactor went critical for the first time in October, the engineers turned it off immediately because the PM-2A leaked neutrons, which can harm people. The Army fashioned lead shields and built walls of 55-gallon drums filled with ice and sawdust trying to protect the operators from radiation. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/kUVnYKIUeQU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">‘The Big Picture,’ an Army TV show distributed to U.S. stations, dedicated a 1961 episode to Camp Century and the reactor.</span></figcaption>
</figure>
<p>The PM-2A ran for two years, making fossil fuel-free power and heat and far more neutrons than was safe. </p>
<p>Those stray neutrons caused trouble. Steel pipes and <a href="https://www.osti.gov/servlets/purl/4456377/">the reactor vessel grew increasingly radioactive over time</a>, as did traces of sodium in the snow. Cooling water leaking from the reactor <a href="https://www.osti.gov/servlets/purl/4844195">contained dozens of radioactive isotopes</a> potentially exposing personnel to radiation and leaving a legacy in the ice.</p>
<p>When the reactor was dismantled for shipping, its metal pipes shed radioactive dust. Bulldozed snow that was once bathed in neutrons from the reactor released radioactive flakes of ice.</p>
<p>Franklin must have ingested some of the radioactive isotopes that the leaking neutrons made. In 2002, he had a <a href="https://www.west-point.org/class/usma1955/D/Hist/Century.htm">cancerous prostate and kidney removed</a>. By 2015, the cancer spread to his lungs and bones. He died of kidney cancer on March 8, 2017, as <a href="https://www.west-point.org/class/usma1955/PWP/FranJ.htm">a retired, revered and decorated major general</a>. </p>
<figure class="align-center ">
<img alt="Two men in uniform standing in a hangar." src="https://images.theconversation.com/files/410677/original/file-20210709-27-e1viyu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410677/original/file-20210709-27-e1viyu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410677/original/file-20210709-27-e1viyu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410677/original/file-20210709-27-e1viyu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410677/original/file-20210709-27-e1viyu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=604&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410677/original/file-20210709-27-e1viyu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=604&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410677/original/file-20210709-27-e1viyu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=604&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Joseph Franklin (right) with pieces of the decommissioned PM-2A reactor at Thule Air Base.</span>
<span class="attribution"><span class="source">U.S. Army Photograph, from Franklin Family, Dignity Memorial</span></span>
</figcaption>
</figure>
<h2>Camp Century’s radioactive legacy</h2>
<p>Camp Century was shut down in 1967. During its <a href="https://www.sciencemag.org/news/2019/10/ancient-soil-secret-greenland-base-suggests-earth-could-lose-lot-ice">eight-year life</a>, scientists had used the base to drill down through the ice sheet and extract an ice core that <a href="https://scholar.google.com/citations?user=nZ6d2zUAAAAJ&hl=en">my colleagues and I</a> are still using today to <a href="https://theconversation.com/ancient-leaves-preserved-under-a-mile-of-greenlands-ice-and-lost-in-a-freezer-for-years-hold-lessons-about-climate-change-157105">reveal secrets of the ice sheet’s ancient past</a>. Camp Century, its ice core and climate change are the focus of a book I am now writing.</p>
<p>The PM-2A was found to be highly radioactive and was buried in an Idaho nuclear waste dump. <a href="https://www.southpolestation.com/oaes/tr__174_camp_century.pdf">Army “hot waste” dumping records</a> indicate it left radioactive cooling water buried in a sump in the Greenland ice sheet.</p>
<p>When <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL069688">scientists studying Camp Century in 2016</a> suggested that the warming climate now <a href="https://theconversation.com/shrinking-glaciers-have-created-a-new-normal-for-greenlands-ice-sheet-consistent-ice-loss-for-the-foreseeable-future-144992">melting Greenland’s ice</a> could expose the camp and its waste, including lead, fuel oil, PCBs and possibly radiation, by 2100, <a href="https://www.climatechangenews.com/2016/10/17/greenland-warns-denmark-over-thawing-us-military-bases/">relations between the U.S, Denmark and Greenland grew tense</a>. Who would be responsible for the cleanup and any environmental damage?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/410199/original/file-20210707-27-1pxg1qd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of Camp Century reactor in trenches" src="https://images.theconversation.com/files/410199/original/file-20210707-27-1pxg1qd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410199/original/file-20210707-27-1pxg1qd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410199/original/file-20210707-27-1pxg1qd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410199/original/file-20210707-27-1pxg1qd.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410199/original/file-20210707-27-1pxg1qd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=604&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410199/original/file-20210707-27-1pxg1qd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=604&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410199/original/file-20210707-27-1pxg1qd.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=604&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A schematic diagram of Camp Century’s nuclear reactor in the Greenland ice sheet.</span>
<span class="attribution"><span class="source">U.S. Army Corps of Engineers.</span></span>
</figcaption>
</figure>
<h2>Portable nuclear reactors today</h2>
<p>There are <a href="https://theconversation.com/how-nuclear-power-generating-reactors-have-evolved-since-their-birth-in-the-1950s-36046">major differences</a> between nuclear power production in the 1960s and today. </p>
<p>The Pele reactor’s <a href="https://physicstoday.scitation.org/do/10.1063/PT.6.2.20210628a/full/">fuel will be sealed in pellets the size of poppy seeds</a>, and it will be air-cooled so there’s no radioactive coolant to dispose of.</p>
<p>Being able to produce energy with fewer greenhouse emissions is a positive in a warming world. The U.S. military’s liquid fuel use <a href="https://www.eurekalert.org/pub_releases/2019-06/lu-umc061919.php">is close to all of Portugal’s or Peru’s</a>. Not having to supply remote bases with as much fuel can also help protect lives in dangerous locations. </p>
<p>But, the U.S. still has <a href="https://news.stanford.edu/2021/03/24/biden-can-jumpstart-u-s-nuclear-waste-strategy/">no coherent national strategy</a> for nuclear waste disposal, and critics are asking <a href="https://thebulletin.org/2019/02/the-pentagon-wants-to-boldly-go-where-no-nuclear-reactor-has-gone-before-it-wont-work/">what happens if Pele falls into enemy hands</a>. Researchers at the Nuclear Regulatory Commission and the National Academy of Sciences have <a href="https://www.nap.edu/read/21874/chapter/7#90">previously questioned the risks</a> of nuclear reactors being attacked by terrorists. As proposals for portable reactors undergo review over the coming months, these and other concerns will be drawing attention.</p>
<p>The U.S. military’s first attempts at land-based portable nuclear reactors didn’t work out well in terms of environmental contamination, cost, human health and international relations. That history is worth remembering as the military considers new mobile reactors.</p>
<p>[<em>Get our best science, health and technology stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-best">Sign up for The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/164138/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Bierman receives funding from the U.S. National Science Foundation</span></em></p>
Nearly 60 years after a radiation-leaking reactor was removed from a US Army base on the Greenland ice sheet, the military is exploring portable nuclear reactors again.
Paul Bierman, Fellow of the Gund Institute for Environment, Professor of Natural Resources, University of Vermont
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/160477
2021-05-17T10:22:02Z
2021-05-17T10:22:02Z
Life in the deep freeze – the revolution that changed our view of glaciers forever
<figure><img src="https://images.theconversation.com/files/399492/original/file-20210507-17-1dedwyb.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5615%2C3741&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/perito-moreno-glacier-located-los-glaciares-599713124">Saiko3p/Shutterstock</a></span></figcaption></figure><p>I’ve been fascinated by glaciers since I was 14, when geography textbooks taught me about strange rivers of ice that crept down yawning valleys like giant serpents stalking their next meal. That kernel of wonder has carried me through a career of more than 25 years. I’ve travelled to the world’s peaks and its poles to see over 20 glaciers. Yet, when I first started out as a researcher in the early 1990s, we were convinced glaciers were lifeless deserts.</p>
<p>Then in 1999, <a href="https://pubs.geoscienceworld.org/gsa/geology/article-abstract/27/2/107/207041/Widespread-bacterial-populations-at-glacier-beds?redirectedFrom=fulltext">Professor Martin Sharp and colleagues</a> discovered bacteria living beneath the Haut Glacier d’Arolla in Switzerland. It seemed that glaciers, like the soil or our stomachs, had their own community of microbes, their own microbiome. Since then, we’ve found microorganisms just about everywhere within glaciers, transforming what we thought were sterile wastelands into vibrant ecosystems. </p>
<p>So what’s all that glacier life doing? These life forms may be invisible to the naked eye, but they can control how fast glaciers melt – and may even influence the global climate.</p>
<h2>The glacier microbiome</h2>
<p>Just like people, glacier microbes modify their homes. When I first saw the melting fringes of Greenland’s vast ice sheet, it looked as if a dust storm had scattered a vast blanket of dirt on the ice. Our team later discovered the dirt included extensive mats of <a href="https://www.nature.com/articles/ismej2012107">glacier algae</a>. These microscopic plant-like organisms contain <a href="https://academic.oup.com/femsec/article/94/3/fiy025/4850643">pigments</a> to help them harvest the Sun’s rays and protect them from harsh UV radiation. By coating the melting ice surface, they darken it, ensuring the ice absorbs more sunlight which causes more of it to melt. In western Greenland, <a href="https://tc.copernicus.org/articles/14/309/2020/">more than 10%</a> of the summer ice melt is caused by algae.</p>
<figure class="align-center ">
<img alt="Bright blue glacier ice on rocky terrain." src="https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&rect=0%2C0%2C3072%2C2304&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The margin of Engabreen glacier, Norway.</span>
<span class="attribution"><span class="source">Grzegorz Lis</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Again, just like us, microbes extract things from their environment to survive. The murky depths of glaciers are among the most challenging habitats for life on Earth. Microbes called <a href="https://aem.asm.org/content/80/19/6146">chemolithotrophs</a> – from the Greek meaning “eaters of rock” – survive here without light and get their energy from breaking down rock, releasing vital nutrients like iron, phosphorous and silicon to the meltwater. </p>
<p><a href="https://www.geochemicalperspectivesletters.org/article1510/">Rivers</a> and <a href="https://geochemicaltransactions.biomedcentral.com/articles/10.1186/1467-4866-9-7">icebergs</a> carry these nutrients to the ocean where they sustain the plant-like phytoplankton – the base of marine food webs which ultimately feed entire ecosystems, from microscopic animals, to fish and even whales. <a href="https://bg.copernicus.org/articles/11/2635/2014/bg-11-2635-2014.html">Models</a> and <a href="https://www.nature.com/articles/ngeo2633">satellite</a> observations show a lot of the photosynthesis in the iron-starved Southern Ocean could be sustained by rusty icebergs and meltwaters, which contain iron unlocked by glacier microbes. Recent evidence suggests something similar occurs off <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL073583">west</a> and <a href="https://www.nature.com/articles/s41598-019-53723-z">east</a> Greenland too.</p>
<figure class="align-center ">
<img alt="A microscope image depicting chains of brown rectangular cells." src="https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Glacier algae from the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Chris Williamson</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But glacier bugs also produce waste, the most worrying of which is the greenhouse gas methane. When ice sheets grow, they bury <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007GB002951">old soils and sediments</a>, all sources of carbon and the building blocks for earthly life. We think there could be thousands of billions of tonnes of <a href="https://www.nature.com/articles/nature11374">carbon buried beneath ice sheets</a> – potentially more than <a href="https://bg.copernicus.org/articles/11/6573/2014/">Arctic permafrost</a>. But who can use it in the oxygen-starved belly of an ice sheet? One type of microbe that flourishes here is <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2012.02763.x">the methanogen</a> (meaning “methane maker”), which also thrives in landfill sites and rice paddies.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A waterfall at the edge of a glacier." src="https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=896&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=896&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=896&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1126&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1126&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1126&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leverett Glacier’s wild river, Greenland.</span>
<span class="attribution"><span class="source">Jemma Wadham</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Some methane produced by methanogens escapes in meltwaters flowing from the ice sheet edges. The clever thing about microbial communities, though, is that one microbe’s waste is another’s food. We humans could learn a lot from them about recycling. Some methane beneath glaciers is consumed by bacteria called methanotrophs (methane eaters) which generate energy by converting it to carbon dioxide. They have been detected in <a href="https://www.nature.com/articles/ismej201459">Greenlandic glaciers</a>, but most notably in <a href="https://www.nature.com/articles/ngeo2992?WT.feed_name=subjects_climate-sciences">Lake Whillans</a> beneath the West Antarctic Ice Sheet. Here, bacteria have years to chomp on the gas, and almost all of the methane produced in the lake is eaten – a good thing for the climate, since carbon dioxide is 80 times less potent as a greenhouse gas when measured over two decades.</p>
<p>We’re not sure this happens everywhere though. Fast-flowing rivers emerging from the Greenland Ice Sheet are <a href="https://www.nature.com/articles/s41586-018-0800-0">super-saturated with microbial methane</a> because there just isn’t enough time for the methanotrophs to get to work. Will melting glaciers release stored methane faster than these bacteria can convert it?</p>
<p>Within the thick interior of ice sheets, scientists worry that there may be vast reserves of methane. The cold and high pressure here mean that it may be trapped in its solid form, methane hydrate (or clathrate), which is stable unless the ice retreats and thins. <a href="https://science.sciencemag.org/content/356/6341/948.abstract">It happened before</a> and it could happen again.</p>
<h2>Waking the sleeping giant</h2>
<p>Despite the climate crisis, when I spend time around glaciers I’m not surprised by their continuing vitality. As I amble up to the gently sloping snout of a glacier – traversing its rubbly lunar-like fore-fields – I often feel like I’m approaching the hulk of an enormous creature. Sleeping or seemingly dormant, the evidence of its last meal is clear from the mass of tawny-coloured rocks, pebbles and boulders strewn around its edges – a tantalising record of where it once rested when the climate was cooler.</p>
<p>As I get closer, I catch the sound of the glacier’s roaring chocolate meltwaters as they explode through an ice cave, punctuated by a cascade of bangs and booms as moving ice collapses into hollow melt channels below. The winds off the ice play ominously in my ears, like the whisper of the beast, a warning: “You’re on my land now.”</p>
<figure class="align-center ">
<img alt="The author inside a giant icy chasm within a glacier." src="https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Exploring a frozen melt channel of the Finsterwalderbeeen glacier in Svalbard.</span>
<span class="attribution"><span class="source">Jon Ove Hagen</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This sense of aliveness with glaciers changes everything. Resident microbes connect these hulking frozen masses with the Earth’s carbon cycle, ecosystems and climate. How will these connections change if we take away the frigid homes of our tiny glacier dwellers? These creatures may be microscopic, but the effects of their industry span entire continents and oceans.</p>
<p>After a period of uncertainty in my own life, which involved the removal of a satsuma-sized growth in my brain, I felt compelled to tell the story of glaciers to a wider audience. My book, <a href="https://www.penguin.co.uk/books/319/319535/ice-rivers/9780241467688.html">Ice Rivers</a>, is the result. I hope the memoir raises awareness of the dramatic changes that threaten glaciers – unless we act now.</p><img src="https://counter.theconversation.com/content/160477/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jemma is Director of the Cabot Institute for the Environment at the University of Bristol, and holds an adjunct professorship at UiT, the Arctic University of Norway. She has received grant funding in the past from the Engineering and Physics Research Council UK, Natural Environment Research Council UK, the Leverhulme Trust, The Royal Society, The British Council, EU Horizon 2020 and the Research Council of Norway. She is the author of Ice Rivers (Allen Lane-Penguin Press, Jemma Wadham Ltd). </span></em></p>
Glaciers aren’t sterile wastelands – they’re chock-full of microscopic life.
Jemma Wadham, Professor of Glaciology, University of Bristol
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/160885
2021-05-14T18:05:13Z
2021-05-14T18:05:13Z
How cables in glaciers could help forecast future sea level rise
<figure><img src="https://images.theconversation.com/files/400604/original/file-20210513-21-1wruqg3.jpg?ixlib=rb-1.1.0&rect=0%2C12%2C4025%2C3005&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Greenland Ice Sheet is the world's second largest body of ice</span> <span class="attribution"><span class="source">Robert Law</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Fibre-optic cables usually make us think of ultra-fast internet – or maybe the irritation of new installation works digging up the pavement. But there are now such cables snaking their way through the centre of the planet’s second largest body of ice, the Greenland ice sheet.</p>
<p>Fibre-optic technologies are allowing us to monitor the internal structure of glaciers in unprecedented levels of detail. <a href="https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.abe7136">In our new study</a>, we show how fibre-optics are offering extraordinary new insight into how ice sheets evolve – and how the movement of Greenland’s glaciers is far more complicated than previously thought.</p>
<p>Ice loss from Greenland has <a href="https://doi.org/10.1073/pnas.1904242116">increased sixfold since the 1980s</a>, and the melting ice sheet is now the <a href="https://doi.org/10.1038/s41467-020-20011-8">single biggest contributor</a> to global sea level rise. In order to forecast the ice sheet’s future – including its worrying rates of melting – we need to understand the thermodynamic processes at work within it. That means we need to take its temperature as accurately as we can. </p>
<p>Surface conditions can be detected simply enough using satellites or <a href="https://www.businessinsider.com/greeland-ice-sheet-turned-black-melts-faster-because-of-algae-2021-3?r=DE&IR=T">in-person observations</a>, but plumbing the deepest reaches of the ice sheet, a moving block of ice a kilometre thick, is a whole different challenge.</p>
<p>This is where fibre-optics come in. In any home broadband network, information travels through fibre-optic cables as a series of light pulses. We use a similar idea in our work, firing bursts of light from a laser into a length of cable. </p>
<p>However, the cable isn’t perfectly smooth: so as the light travels, some will be reflected from tiny flaws in the cable wall, much like how light bounces off the reflective shards on a disco ball. As the cable changes temperature, or is stretched slightly by tiny earthquakes, the flaws changes: and so do the characteristics of the reflections. By continually monitoring these changes, we build up a detailed picture of what the glacier is like deep under its icy surface. </p>
<figure class="align-center ">
<img alt="A man raises a hammer above an icy tundra surrounded by equipment" src="https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Taking a sledgehammer to the ice mimics seismic shockwaves.</span>
<span class="attribution"><span class="source">Adam Booth</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>As part of the EU-funded <a href="https://www.erc-responder.eu/">RESPONDER project</a> based at the <a href="https://www.spri.cam.ac.uk/">Scott Polar Research Institute</a>, University of Cambridge, we installed a kilometre-long stretch of fibre-optic cable to explore the properties of Sermeq Kujalleq, also known as Store Glacier, in West Greenland. Situated 28km from the front of the glacier, our study site creeps west at a rate of around 500 metres per year. </p>
<p>To get the cable in place, colleagues from <a href="https://www.aber.ac.uk/en/dges/research/centre-glaciology/">Aberystwyth University</a> used a hot-water drill to bore a 1,040-metre hole downwards through the ice before we threaded the cable in. The cable connects at the surface to a computer, called an interrogator, which fires and records the laser pulses. </p>
<p>Over six weeks, we monitored the cable to determine the temperature differences throughout the glacier’s layers. We also investigated ice stiffness, an indicator of how easily ice flows, by measuring variations in how quickly <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL088148">seismic vibrations</a> travel through the ice along the cable length: faster vibrations can indicate stiffer ice. For this, we made our own <a href="https://www.nature.com/articles/s43017-021-00176-6.epdf?sharing_token=0yan-HW5Qlwtkn524n42J9RgN0jAjWel9jnR3ZoTv0OwAreHKMhA7jKEtPMDxjS257nBx0-e_jzrqs7Lr8pBnLgy9pCUkVhbcrwhO5fyOv0ViYJsavEMtLn41vwpk6xbzf5jDj6Km9JFp4UzVgTXYOHnH84SmUtN90ksyxDJ7pI%3D">DIY shockwaves</a> by hitting the surface of the glacier with a sledgehammer.</p>
<figure> <img src="https://media.giphy.com/media/RUTAHot2ogFTCodPvx/giphy.gif"> <figcaption>Adam Booth makes mini earthquakes. Video by Poul Christoffersen</figcaption></figure>
<h2>The anatomy of a glacier</h2>
<p>The result is the most detailed description to date of the thermal and mechanical structure of the glacier. The internal temperature of glaciers is controlled by a few key processes. At their centre lies a core of extremely cold, stiff ice. As it continues its journey coastwards, the glacier surface is heated to -6.5°C – tropical in comparison – by sunlight and warmer air. </p>
<p>But nearest to the ground, the glacier is warmer still, as the constant churning of internal ice crystals generates heat. Add the heat naturally radiating from within the earth, and ice temperature approaches 0°C. </p>
<p>At these depths, ice coexists with small pockets of liquid water, similar to how snow becomes slush. We call such ice “temperate” and, in terms of glacier flow and eventual ice loss, it’s where the action is. That means it’s vital to understand how much temperate ice we’ve got.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=778&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=778&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=778&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=978&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=978&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=978&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Our temperature results (black line). The coldest ice is in the very centre of the ice column, heated at the surface by the atmosphere and at the bottom by the ice deforming around itself and heat radiated out from the Earth.</span>
<span class="attribution"><span class="source">Robert Law</span></span>
</figcaption>
</figure>
<p>So what did we find?</p>
<p>First, the heat map of our glacier showed far more variability than we’d expected. We found concentrated patches of heat in areas where the ice was particularly deformed, even at relatively shallow depths – something never previously observed in glacier ice. </p>
<p>Second, we observed three distinct ice layers within the glacier. Two of these were predictable. The upper 890 metres of the glacier was made of cold and stiff ice. Beneath that was older, weaker ice dating back to the last ice age. This ice is weaker because it contains particles of ice age dust, which disrupts the bonds between individual ice crystals. </p>
<figure class="align-center ">
<img alt="People stand around large equipment on an icy surface" src="https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The research team bores through the ice to install the fibre-optic cable.</span>
<span class="attribution"><span class="source">Adam Booth</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But the biggest surprise of all was hiding in the lowermost 70 metres of the glacier, where we found a large quantity of temperate ice. This might be expected in warm Alpine environments, but at such depths in Sermeq Kujalleq, the heat required to produce liquid water can only be produced by significant ice deformation: evidence of just how dynamic the base of the ice sheet is. </p>
<p>These observations not only help explain why the Greenland ice sheet is losing so much mass, they also help us predict future patterns of ice loss and sea level rise.</p><img src="https://counter.theconversation.com/content/160885/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Law receives funding from Natural Environment Research Council and European Research Council.</span></em></p><p class="fine-print"><em><span>Adam Booth does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
New research shows how fibre-optic cables can monitor the hidden structure of glaciers, teaching us about past and future ice flow.
Robert Law, PhD candidate, University of Cambridge
Adam Booth, Associate Professor in Applied Geophysics, School of Earth and Environment, University of Leeds
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/149341
2021-04-19T12:27:36Z
2021-04-19T12:27:36Z
Competition heats up in the melting Arctic, and the US isn’t prepared to counter Russia
<figure><img src="https://images.theconversation.com/files/395568/original/file-20210417-15-1qcv628.jpg?ixlib=rb-1.1.0&rect=235%2C770%2C3695%2C2051&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Russia has been beefing up its Arctic icebreaker fleet to take advantage of the changing climate.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/the-50-let-pobedy-50th-anniversary-of-victory-nuclear-news-photo/1135830248">Lev Fedoseyev\TASS via Getty Images</a></span></figcaption></figure><p>For decades, the frozen Arctic was little more than a footnote in global economic competition, but that’s changing as its ice melts with the warming climate.</p>
<p>Russia is now attempting to claim <a href="https://www.un.org/depts/los/clcs_new/submissions_files/submission_rus_rev1.htm">more of the Arctic seabed</a> for its territory. It has been rebuilding Cold War-era Arctic military bases and recently announced plans to test its Poseidon nuclear-powered, <a href="https://www.thetimes.co.uk/article/russia-sends-doomsday-nuclear-powered-torpedo-for-test-in-the-arctic-wf5ttr260">nuclear-armed torpedo</a> in the Arctic. In Greenland, the recent election ushered in a new pro-independence government that opposes foreign <a href="https://www.nytimes.com/2021/04/07/world/europe/left-wing-greenland-election-mine.html">rare earth metal mining</a> as its ice sheet recedes – including projects counted on by China and the U.S. <a href="https://theconversation.com/the-us-is-worried-about-its-critical-minerals-supply-chains-essential-for-electric-vehicles-wind-power-and-the-nations-defense-157465">to power technology</a>. </p>
<p>The Arctic region has been warming <a href="https://theconversation.com/100-degrees-in-siberia-5-ways-the-extreme-arctic-heat-wave-follows-a-disturbing-pattern-141442">at least twice as fast</a> as the planet as a whole. With the sea ice now thinner and disappearing sooner in the spring, several countries have had their eyes on the Arctic, both for access to <a href="https://www.eia.gov/analysis/studies/archive/2009/arctic/index.html">valuable natural resources</a>, including the fossil fuels whose use is now <a href="https://science2017.globalchange.gov/">driving global warming</a>, and as a shorter route for commercial ships. A tanker carrying liquefied natural gas from northern Russia to China tested that shorter route this past winter, <a href="https://www.maritime-executive.com/article/russian-lng-carrier-completes-winter-trips-on-the-northern-sea-route">traversing the normally frozen Northern Sea Route</a> in February for the first time with the help of an icebreaker. The route cut the shipping time by <a href="https://www.reuters.com/article/us-novatek-cnpc-lng/russias-novatek-ships-first-lng-cargo-to-china-via-arctic-idUSKBN1K90YN">nearly half</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/395412/original/file-20210416-17-15qz7tp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A round map with a view centered on the North Pole showing shipping routes" src="https://images.theconversation.com/files/395412/original/file-20210416-17-15qz7tp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/395412/original/file-20210416-17-15qz7tp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=569&fit=crop&dpr=1 600w, https://images.theconversation.com/files/395412/original/file-20210416-17-15qz7tp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=569&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/395412/original/file-20210416-17-15qz7tp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=569&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/395412/original/file-20210416-17-15qz7tp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=716&fit=crop&dpr=1 754w, https://images.theconversation.com/files/395412/original/file-20210416-17-15qz7tp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=716&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/395412/original/file-20210416-17-15qz7tp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=716&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Arctic shipping routes.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Northern_Sea_Route#/media/File:Map_of_the_Arctic_region_showing_the_Northeast_Passage,_the_Northern_Sea_Route_and_Northwest_Passage,_and_bathymetry.png">Susie Harder/Arctic Council</a></span>
</figcaption>
</figure>
<p>Russia has been building up its icebreaker fleet for years for these and other purposes. The U.S., meanwhile, is playing catch-up. While Russia has access to <a href="https://www.dco.uscg.mil/Our-Organization/Assistant-Commandant-for-Prevention-Policy-CG-5P/Marine-Transportation-Systems-CG-5PW/Office-of-Waterways-and-Ocean-Policy/Office-of-Waterways-and-Ocean-Policy-Mobility-and-Ice-Operations/">more than 40</a> of these ships today, the U.S. Coast Guard has two, one of them well past its intended service life. </p>
<p>As an <a href="https://fletcher.tufts.edu/people/rockford-weitz">expert in maritime trade and Arctic geopolitics</a>, I have been following the increasing activity and <a href="https://www.nytimes.com/2021/04/15/world/europe/us-russia-sanctions.html">geopolitical tensions</a> in the Arctic. They underscore the need for fresh thinking on U.S. Arctic policy to address emerging competition in the region. </p>
<h2>The problem with America’s icebreaker fleet</h2>
<p>America’s aging icebreaker fleet has been a persistent topic of frustration in Washington. </p>
<p>Congress put off investing in new icebreakers for decades in the face of more pressing demands. Now, the lack of polar-class icebreakers undermines America’s ability to <a href="https://www.dvidshub.net/video/582402/coast-guard-cutter-polar-star-breaks-ice-supporting-operation-deep-freeze-2018">operate in the</a> Arctic region, including responding to disasters as shipping and mineral exploration increase. </p>
<p>It might sound counterintuitive, but diminishing sea ice can make the region more dangerous – breakaway ice floes pose <a href="https://www.maritime-executive.com/article/icebergs-disrupt-north-atlantic-shipping">risks both to ships and to oil platforms</a>, and the opening waters are expected to attract both more shipping and more mineral exploration. The U.S. Geological Survey estimates that about 30% of the world’s undiscovered natural gas and 13% of undiscovered oil <a href="https://science.sciencemag.org/content/324/5931/1175">may be in the Arctic</a>. </p>
<figure class="align-center ">
<img alt="People walk on the ice beside the giant icebreaker" src="https://images.theconversation.com/files/395565/original/file-20210417-17-1ixnw7a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/395565/original/file-20210417-17-1ixnw7a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/395565/original/file-20210417-17-1ixnw7a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/395565/original/file-20210417-17-1ixnw7a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/395565/original/file-20210417-17-1ixnw7a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/395565/original/file-20210417-17-1ixnw7a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/395565/original/file-20210417-17-1ixnw7a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Polar Star icebreaker is 45 years old and in need of replacement.</span>
<span class="attribution"><a class="source" href="https://www.dvidshub.net/image/1078451/polar-star-antarctic-trip-2006">Mariana O'Leary/U.S. Coast Guard</a></span>
</figcaption>
</figure>
<p>The U.S. Coast Guard has just two icebreakers to manage this changing environment. </p>
<p>The <a href="https://www.pacificarea.uscg.mil/Our-Organization/Cutters/cgcPolarStar/">Polar Star</a>, a heavy icebreaker that can break through ice up to 21 feet thick, was commissioned in 1976. It is usually posted to Antarctica in the winter, but it was <a href="https://www.navytimes.com/news/your-navy/2020/12/02/coast-guard-icebreaker-polar-star-heading-to-arctic-as-covid-19-limits-antarctic-operations/">sent to the Arctic</a> this year to provide a U.S. presence. The crew on the aging ship has had to <a href="https://www.military.com/daily-news/2019/08/16/meet-polar-star-coast-guards-vital-neglected-icebreaker-its-falling-apart.html">fight fires</a> and deal with power outages and equipment breaks – all while in some of the most inhospitable and remote locations on Earth. The second icebreaker, the smaller <a href="https://www.pacificarea.uscg.mil/Our-Organization/Cutters/cgcHealy/">Healy</a>, commissioned in 2000, suffered a fire on board in August 2020 and <a href="https://news.usni.org/2020/08/25/coast-guard-icebreaker-healy-suffers-fire-on-arctic-mission-all-arctic-operations-cancelled">canceled all Arctic operations</a>.</p>
<figure class="align-center ">
<img alt="Two Coast Guard crew members, a man and a woman, work amid pipes on the ship." src="https://images.theconversation.com/files/395564/original/file-20210417-23-1krdxnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/395564/original/file-20210417-23-1krdxnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/395564/original/file-20210417-23-1krdxnl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/395564/original/file-20210417-23-1krdxnl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/395564/original/file-20210417-23-1krdxnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/395564/original/file-20210417-23-1krdxnl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/395564/original/file-20210417-23-1krdxnl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Engineers aboard the Polar Star fix a saltwater pump while in the Bering Sea on Jan. 28, 2021.</span>
<span class="attribution"><a class="source" href="https://www.dvidshub.net/image/6505575/coast-guard-cutter-polar-star-arctic-west-winter-2021">Cynthia Oldham/U.S. Coast Guard</a></span>
</figcaption>
</figure>
<p>Congress has <a href="https://crsreports.congress.gov/product/pdf/RL/RL34391/196">authorized construction of three more heavy icebreakers</a> at a total cost of around US$2.6 billion and has funded two of them so far, but they take years to produce. A shipyard in Mississippi expects to deliver the first by 2024.</p>
<h2>An icebreaker solution</h2>
<p>One way to add to the icebreaker fleet would be to have allies jointly procure and operate icebreakers, while each still builds up its own fleet. </p>
<p>For example, the Biden administration could collaborate with NATO allies to create a partnership modeled on NATO’s <a href="https://www.nspa.nato.int/about/namp/sac%5D">Strategic Airlift Capability</a> of C-17 airplanes. The airlift program, started in 2008, operates three large transport planes that its 12 member nations can use to quickly transport troops and equipment.</p>
<p>A similar program for icebreakers could operate a fleet under NATO – perhaps starting with icebreakers contributed by NATO countries, such as Canada, or partner countries, such as Finland. Like the Strategic Airlift Capability, each member country would purchase a percentage of the shared fleet’s operating hours based on their overall contributions to the program. </p>
<p>U.S. Defense Secretary Lloyd Austin announced a step toward more of this kind of collaboration on June 9, 2021, with plans to establish a new <a href="https://www.defense.gov/Newsroom/Releases/Release/Article/2651852/the-department-of-defense-announces-establishment-of-arctic-regional-center/">Center for Arctic Security Studies</a>, the sixth <a href="https://www.dsca.mil/dod-regional-centers-rc">Department of Defense Regional Center</a>. The centers focus on research, communications, and collaboration with partners.</p>
<h2>Using the Law of the Sea</h2>
<p>Another strategy that could boost U.S. influence in the Arctic, buffer looming conflicts, and help clarify seabed claims would be for the Senate to ratify the <a href="https://www.un.org/depts/los/convention_agreements/convention_overview_convention.htm">United Nations Convention on the Law of the Sea</a>.</p>
<figure class="align-center ">
<img alt="Russian President Vladimir Putin stands a man who is pointing outside the lit-up LNG plant." src="https://images.theconversation.com/files/395569/original/file-20210417-21-r9fhtq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/395569/original/file-20210417-21-r9fhtq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/395569/original/file-20210417-21-r9fhtq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/395569/original/file-20210417-21-r9fhtq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/395569/original/file-20210417-21-r9fhtq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/395569/original/file-20210417-21-r9fhtq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/395569/original/file-20210417-21-r9fhtq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Russia recently opened a large liquefied natural gas plant on the Kara Sea, above the Arctic Circle.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/russian-president-vladimir-putin-listens-to-novatek-ceo-news-photo/888363240">Mikhail Svetlov/Getty Images</a></span>
</figcaption>
</figure>
<p>The Law of the Sea took effect in 1994 and established rules for how the oceans and ocean resources are used and shared. That includes determining how countries can claim parts of the seabed. The U.S. initially objected over a section that limited deep seabed mining, but <a href="https://www.govinfo.gov/content/pkg/CHRG-110shrg45282/html/CHRG-110shrg45282.htm">that section was amended</a> to alleviate some of those concerns. Presidents Bill Clinton, George W. Bush and Barack Obama <a href="https://sites.tufts.edu/lawofthesea/chapter-eleven/">all urged the Senate to ratify it</a>, but that <a href="https://www.congress.gov/bill/116th-congress/senate-resolution/284/text">still has not happened</a>. </p>
<p>Ratification would give the U.S. a stronger international legal position in contested waters. It also would enable the U.S. to claim more than 386,000 square miles – an area twice the size of California – <a href="https://www.cfr.org/report/arctic-imperatives">of Arctic seabed along its extended continental shelf</a> and fend off any other country’s overlapping claims to that area. </p>
<p>Without ratification, the U.S. will be forced to rely on <a href="https://sites.tufts.edu/lawofthesea/chapter-one/">customary international law to pursue any maritime claims</a>, which weakens its <a href="https://sites.tufts.edu/lawofthesea/chapter-eleven/">international legal position in contested waters</a>, including the <a href="https://sites.tufts.edu/lawofthesea/chapter-eight/">Arctic</a> and the <a href="https://sites.tufts.edu/lawofthesea/chapter-ten/">South China Sea</a>.</p>
<h2>Relying on international cooperation</h2>
<p>The Arctic has generally been a region of international cooperation. <a href="https://arctic-council.org/en">The Arctic Council</a>, an international body, has kept eight countries with sovereignty over land in the region focused on the Arctic’s fragile ecosystem, the well-being of its Indigenous peoples, and emergency prevention and response. </p>
<p>Over the past few years, however, <a href="https://arctic-council.org/en/about/observers/">“near-Arctic” countries</a>, including China, Japan, South Korea, Britain and many European Union members, have become more engaged, and Russia has become more active.</p>
<p>With the rising tensions and expanding interest in the region, the era of cooperative engagement has started to recede with the melting sea ice. </p>
<p><em>This article was updated with the Defense Department announcing plans on June 9, 2021, to establish a new center to promote collaboration in the Arctic.</em></p><img src="https://counter.theconversation.com/content/149341/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rockford Weitz receives funding from the Smith Richardson Foundation to study emerging maritime security challenges, including those in the Arctic Ocean region. In addition to his position at Tufts University, he serves as a Board Director and President at the Institute for Global Maritime Studies Inc., a Massachusetts-based research and education non-profit, and as an advisor and investor in OceanShield Pte. Ltd., a maritime cyber-security startup.</span></em></p>
Russia is attempting to claim more of the Arctic seabed, an area rich in oil, gas and minerals. It’s also expanding shipping and reopening Arctic bases. Here are two things the U.S. can do about it.
Rockford Weitz, Professor of Practice & Director, Fletcher Maritime Studies Program, The Fletcher School, Tufts University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/157105
2021-03-15T19:07:07Z
2021-03-15T19:07:07Z
Ancient leaves preserved under a mile of Greenland’s ice – and lost in a freezer for years – hold lessons about climate change
<figure><img src="https://images.theconversation.com/files/389429/original/file-20210314-20-1edaygc.png?ixlib=rb-1.1.0&rect=0%2C0%2C8004%2C4493&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Remnants of ancient Greenland tundra were preserved in soil beneath the ice sheet.</span> <span class="attribution"><a class="source" href="https://doi.org/10.1073/pnas.2021442118">Andrew Christ and Dorothy Peteet</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>In 1963, inside a covert U.S. military base in northern Greenland, a team of scientists <a href="https://icedrill.org/sites/default/files/SR-126.pdf">began drilling</a> down through the Greenland ice sheet. Piece by piece, they extracted an ice core 4 inches across and nearly a mile long. At the very end, they pulled up something else – 12 feet of frozen soil.</p>
<p>The ice told a story of Earth’s climate history. The frozen soil was examined, set aside and then forgotten. </p>
<p>Half a century later, scientists rediscovered that soil in a Danish freezer. It is now revealing its secrets.</p>
<p>Using lab techniques unimaginable in the 1960s when the core was drilled, we and an international team of fellow scientists were able to show that Greenland’s massive ice sheet had melted to the ground there within the past million years. Radiocarbon dating shows that it would have happened more than 50,000 years ago. It most likely happened during times when the climate was warm and sea level was high, possibly 400,000 years ago.</p>
<p>And there was more. As we explored the soil under a microscope, we were stunned to discover the remnants of a tundra ecosystem – twigs, leaves and moss. We were looking at northern Greenland as it existed the last time the region was ice-free. Our <a href="https://doi.org/10.1073/pnas.2021442118">peer-reviewed study</a> was published on March 15, 2021 in <a href="https://www.pnas.org">Proceedings of the National Academy of Sciences</a>. </p>
<figure class="align-center ">
<img alt="A drilling rig in a trench dug deep into the ice ." src="https://images.theconversation.com/files/564437/original/file-20231208-19-2uftxu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564437/original/file-20231208-19-2uftxu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=761&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564437/original/file-20231208-19-2uftxu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=761&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564437/original/file-20231208-19-2uftxu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=761&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564437/original/file-20231208-19-2uftxu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=956&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564437/original/file-20231208-19-2uftxu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=956&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564437/original/file-20231208-19-2uftxu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=956&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The drilling trench at Camp Century, where sections of ice core are brought to the surface.</span>
<span class="attribution"><a class="source" href="https://repository.aip.org/islandora/object/nbla%3A292052">David Atwood, U.S. Army-ERDC-CRREL, courtesy of AIP Emilio Segrè Visual Archives</a></span>
</figcaption>
</figure>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Ota2-eEN41w?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Paul Bierman, a geomorphologist and geochemist, describes what he and his colleagues found in the soil.</span></figcaption>
</figure>
<p>With no ice sheet, sunlight would have warmed the soil enough for tundra vegetation to cover the landscape. The oceans around the globe would have been more than 10 feet higher, and <a href="https://scied.ucar.edu/learning-zone/climate-change-impacts/greenlands-ice-melting">maybe even 20 feet</a>. The land on which Boston, London and Shanghai sit today would have been under the ocean waves. </p>
<p>The ice core and the soil below are something of a Rosetta Stone for understanding how durable the Greenland ice sheet has been during past warm periods – and how quickly it might melt again as the climate heats up. Today, humans are warming Earth’s climate, and <a href="https://climate.nasa.gov/climate_resources/24/graphic-the-relentless-rise-of-carbon-dioxide/">the carbon dioxide levels in the atmosphere</a> are rising quickly. </p>
<h2>Secret military bases and Danish freezers</h2>
<p>The story of the ice core begins during the Cold War with a military mission dubbed Project Iceworm. Starting around 1959, the U.S. Army hauled hundreds of soldiers, heavy equipment and even a nuclear reactor across the ice sheet in northwest Greenland and dug a base of tunnels inside the ice. They called it <a href="https://www.youtube.com/watch?v=1Ujx_pND9wg">Camp Century</a>.</p>
<p>It was part of a secret plan to hide nuclear weapons from the Soviets. The public knew it as an Arctic research laboratory. Walter Cronkite even paid a visit and <a href="https://www.historicfilms.com/tapes/2705">filed a report</a>.</p>
<figure class="align-center ">
<img alt="Workers cover a trench to build the under-ice military base" src="https://images.theconversation.com/files/389375/original/file-20210313-20-hzxz94.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389375/original/file-20210313-20-hzxz94.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=485&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389375/original/file-20210313-20-hzxz94.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=485&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389375/original/file-20210313-20-hzxz94.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=485&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389375/original/file-20210313-20-hzxz94.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=609&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389375/original/file-20210313-20-hzxz94.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=609&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389375/original/file-20210313-20-hzxz94.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=609&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Workers build the snow tunnels at the Camp Century research base in 1960.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Camp_Century#/media/File:Camp_Century_trench_construction.png">U.S. Army Corps of Engineers</a></span>
</figcaption>
</figure>
<p>Camp Century didn’t last long. The snow and ice began slowly crushing the buildings inside the tunnels below, forcing the military to abandon it in 1966. During its short life, however, scientists were able to extract the ice core and begin analyzing Greenland’s climate history. <a href="https://www.ncdc.noaa.gov/news/picture-climate-what-can-we-learn-ice">As ice builds up</a> year by year, it captures layers of volcanic ash and changes in precipitation over time, and it traps air bubbles that reveal the past composition of the atmosphere.</p>
<p>One of the original scientists, glaciologist Chester Langway, kept the core and soil samples frozen at the University at Buffalo for years, then he shipped them to a Danish archive in the 1990s, where the soil was soon forgotten.</p>
<p>A few years ago, our Danish colleagues found the soil samples in a box of glass cookie jars with faded labels: “Camp Century Sub-Ice.”</p>
<figure class="align-center ">
<img alt="Scientists look at the sediment in jars" src="https://images.theconversation.com/files/389342/original/file-20210313-23-1n4arz6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389342/original/file-20210313-23-1n4arz6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389342/original/file-20210313-23-1n4arz6.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389342/original/file-20210313-23-1n4arz6.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389342/original/file-20210313-23-1n4arz6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389342/original/file-20210313-23-1n4arz6.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389342/original/file-20210313-23-1n4arz6.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Geomorphologist Paul Bierman (right) and geochemist Joerg Schaefer of Columbia University examine the jars holding Camp Century sediment for the first time. They were in a Danish freezer set at -17 F.</span>
<span class="attribution"><span class="source">Paul Bierman</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A surprise under the microscope</h2>
<p>On a hot July day in 2019, two samples of soil arrived at our <a href="https://www.uvm.edu/cosmolab/">lab at the University of Vermont</a> frozen solid. We began the painstaking process of splitting the precious few ounces of frozen mud and sand for different analyses.</p>
<p>First, we photographed the layering in the soil before it was lost forever. Then we chiseled off small bits to examine under the microscope. We melted the rest and saved the ancient water.</p>
<p>Then came the biggest surprise. While we were washing the soil, we spotted something floating in the rinse water. <a href="https://scholar.google.com/citations?user=nZ6d2zUAAAAJ&hl=en">Paul</a> grabbed a pipette and some filter paper, <a href="https://scholar.google.com/citations?user=FlafCtYAAAAJ&hl=en">Drew</a> grabbed tweezers and turned on the microscope. We were absolutely stunned as we looked down the eyepiece.</p>
<p>Staring back at us were leaves, twigs and mosses. This wasn’t just soil. This was an ancient ecosystem perfectly preserved in Greenland’s natural deep freeze.</p>
<figure class="align-center ">
<img alt="One of the authors looking excited" src="https://images.theconversation.com/files/389343/original/file-20210313-21-1io45o4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389343/original/file-20210313-21-1io45o4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389343/original/file-20210313-21-1io45o4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389343/original/file-20210313-21-1io45o4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389343/original/file-20210313-21-1io45o4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389343/original/file-20210313-21-1io45o4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389343/original/file-20210313-21-1io45o4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Glacial geomorphologist Andrew Christ (right), with geology student Landon Williamson, holds up the first fossil twig spotted as they washed a sediment sample from Camp Century.</span>
<span class="attribution"><span class="source">Paul Bierman</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Dating million-year-old moss</h2>
<p>How old were these plants?</p>
<p>Over the last million years, Earth’s climate was punctuated by relatively short warm periods, typically lasting about 10,000 years, called interglacials, when there was less ice at the poles and sea level was higher. The Greenland ice sheet survived through all of human history during the Holocene, the present interglacial period of the last 12,000 years, and most of the interglacials in the last million years. </p>
<p>But our research shows that at least one of these interglacial periods was warm enough for a long enough period of time to melt large portions of the Greenland ice sheet, allowing a tundra ecosystem to emerge in northwestern Greenland.</p>
<p>We used two techniques to determine the age of the soil and the plants. First, we used <a href="https://www.youtube.com/channel/UCSb1dSMVGCr4PzdooW5qSOQ">clean room chemistry</a> and a <a href="https://www.physics.purdue.edu/primelab/">particle accelerator</a> to count atoms that form in rocks and sediment when exposed to natural radiation that bombards Earth. Then, a colleague used an ultra-sensitive method for measuring <a href="http://www.usu.edu/geo/luminlab/">light emitted from grains of sand</a> to determine the last time they were exposed to sunlight.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/389382/original/file-20210313-22-1p9isiu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Maps of Greenland Ice Sheet speed and bedrock elevation" src="https://images.theconversation.com/files/389382/original/file-20210313-22-1p9isiu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389382/original/file-20210313-22-1p9isiu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=498&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389382/original/file-20210313-22-1p9isiu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=498&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389382/original/file-20210313-22-1p9isiu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=498&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389382/original/file-20210313-22-1p9isiu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=626&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389382/original/file-20210313-22-1p9isiu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=626&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389382/original/file-20210313-22-1p9isiu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=626&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Maps of Greenland show the speed of the ice sheet as it flows (left) and the landscape hidden beneath it (right).</span>
<span class="attribution"><span class="source">BedMachine v3; Copernicus Climate Change Service (C3S)</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<figure class="align-center ">
<img alt="Chart of CO2 concentrations over time" src="https://images.theconversation.com/files/389669/original/file-20210315-13-1vsslxu.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389669/original/file-20210315-13-1vsslxu.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389669/original/file-20210315-13-1vsslxu.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389669/original/file-20210315-13-1vsslxu.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389669/original/file-20210315-13-1vsslxu.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389669/original/file-20210315-13-1vsslxu.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389669/original/file-20210315-13-1vsslxu.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The concentration of carbon dioxide in the atmosphere today is well beyond past levels determined from ice cores. On March 14, 2021, the CO2 level was about 417 ppm.</span>
<span class="attribution"><a class="source" href="https://climate.nasa.gov/vital-signs/carbon-dioxide/">NASA Jet Propulsion Laboratory</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The million-year time frame is important. <a href="https://doi.org/10.1038/nature20146">Previous work on another ice core, GISP2, extracted from central Greenland</a> in the 1990s, showed that the ice had also been absent there within the last million years, perhaps about 400,000 years ago.</p>
<h2>Lessons for a world facing rapid climate change</h2>
<p>Losing the Greenland ice sheet would be catastrophic to humanity today. The melted ice would raise sea level by more than 20 feet. That would redraw coastlines worldwide.</p>
<p>About 40% of the global population <a href="https://www.un.org/sustainabledevelopment/wp-content/uploads/2017/05/Ocean-fact-sheet-package.pdf">lives within 60 miles of a coast</a>, and 600 million people live within 30 feet of sea level. <a href="https://nca2018.globalchange.gov/chapter/9/">If warming continues</a>, ice melt from Greenland and Antarctica will pour more water into the oceans. Communities will be forced to relocate, climate refugees will become more common, and costly infrastructure will be abandoned. Already, <a href="https://www.ipcc.ch/srocc/home/">sea level rise has amplified</a> flooding from coastal storms, causing hundreds of billions of dollars of damage every year.</p>
<figure class="align-center ">
<img alt="A rock and tundra with a glacier in the background" src="https://images.theconversation.com/files/389345/original/file-20210313-23-1dfbpfe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389345/original/file-20210313-23-1dfbpfe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=626&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389345/original/file-20210313-23-1dfbpfe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=626&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389345/original/file-20210313-23-1dfbpfe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=626&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389345/original/file-20210313-23-1dfbpfe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=787&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389345/original/file-20210313-23-1dfbpfe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=787&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389345/original/file-20210313-23-1dfbpfe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=787&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tundra near the Greenland ice sheet today. Is this what Camp Century looked like before the ice came back sometime in the last million years?</span>
<span class="attribution"><span class="source">Paul Bierman</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The <a href="https://www.sciencemag.org/news/2019/10/ancient-soil-secret-greenland-base-suggests-earth-could-lose-lot-ice">story of Camp Century</a> spans two critical moments in modern history. An Arctic military base built in response to the existential threat of nuclear war inadvertently led us to discover another threat from ice cores – the threat of sea level rise from human-caused climate change. Now, its legacy is helping scientists understand how the Earth responds to a changing climate.</p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p><img src="https://counter.theconversation.com/content/157105/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Christ receives funding from the Gund Institute for Environment and the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Paul Bierman receives funding from the US National Science Foundation and UVM Gund Institute for Environment.</span></em></p>
This ancient ecosystem showed that the ice sheet had melted to the ground
in northern Greenland within the past million years.
Andrew Christ, Postdoctoral Fellow and Lecturer in Geology, University of Vermont
Paul Bierman, Fellow of the Gund Institute for Environment, Professor of Natural Resources and Environmental Science, University of Vermont
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/150261
2020-11-17T16:45:45Z
2020-11-17T16:45:45Z
Greenland is melting: we need to worry about what’s happening on the largest island in the world
<figure><img src="https://images.theconversation.com/files/369860/original/file-20201117-13-19n3zcw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Jonathan Bamber</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Greenland is the largest island in the world and on it rests the largest ice mass in the Northern Hemisphere. If all that ice melted, the sea would rise by <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL074954">more than 7 metres</a>. </p>
<p>But that’s not going to happen is it? Well not any time soon, but understanding how much of the ice sheet might melt over the coming century is a critical and urgent question that scientists are trying to tackle using sophisticated numerical models of how the ice sheet <a href="https://tc.copernicus.org/articles/14/3071/2020/">interacts with the rest of the climate system</a>. The problem is that the models aren’t that good at reproducing recent observations and are limited by our poor knowledge of the detailed topography of the subglacial terrain and fjords, which the ice flows over and in to.</p>
<p>One way around this problem is to see how the ice sheet responded to changes in climate in the past and compare that with model projections for the future for similar changes in temperature. That is exactly what colleagues and I did in a new study now published in the journal <a href="https://www.nature.com/articles/s41467-020-19580-5">Nature Communications</a>. </p>
<p>We looked at the three largest glaciers in Greenland and used historical aerial photographs combined with measurements scientists had taken directly over the years, to reconstruct how the volume of these glaciers had changed over the period 1880 to 2012. The approach is founded on the idea that the past can help inform the future, not just in science but in all aspects of life. But just like other “classes” of history, the climate and the Earth system in future won’t be a carbon copy of the past. Nonetheless, if we figure out exactly how sensitive the ice sheet has been to temperature changes over the past century, that can provide a useful guide to how it will respond over the next century. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/369795/original/file-20201117-23-1ha07y1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man walks over grassy land with glacier in background" src="https://images.theconversation.com/files/369795/original/file-20201117-23-1ha07y1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/369795/original/file-20201117-23-1ha07y1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/369795/original/file-20201117-23-1ha07y1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/369795/original/file-20201117-23-1ha07y1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/369795/original/file-20201117-23-1ha07y1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/369795/original/file-20201117-23-1ha07y1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/369795/original/file-20201117-23-1ha07y1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Greenland’s glaciers contain around 8% of the world’s fresh water.</span>
<span class="attribution"><span class="source">Jonathan Bamber</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We found that the three largest glaciers were responsible for 8.1mm of sea level rise, about 15% of the whole ice sheet’s contribution. Over the period of our study the sea globally has risen by around 20cm, about the height of an A5 booklet, and of that, about a finger’s width is entirely thanks to ice melting from those three Greenland glaciers.</p>
<h2>Melting As Usual</h2>
<p>So what does that tell us about the future behaviour of the ice sheet? In 2013, a <a href="https://www.nature.com/articles/nature12068">modelling study</a> by Faezeh Nick and colleagues also looked at the same “big three” glaciers (Jakobshavn Isbrae in the west of the island and Helheim and Kangerlussuaq in the east) and projected how they would respond in different future climate scenarios. The most extreme of these scenarios is called <a href="https://www.carbonbrief.org/explainer-the-high-emissions-rcp8-5-global-warming-scenario">RCP8.5</a> and assumes that economic growth will continue unabated through the 21st century, resulting in a global mean warming of about 3.7˚C above today’s temperatures (about 4.8˚C above pre-industrial or since 1850). </p>
<p>This scenario has sometimes been referred to as Business As Usual (BAU) and there is an <a href="https://www.scientificamerican.com/article/the-worst-climate-scenarios-may-no-longer-be-the-most-likely/">active debate</a> among climate researchers regarding how plausible RCP8.5 is. It’s interesting to note, however, that, according to a recent study from a group of US scientists it may be the most appropriate scenario <a href="https://www.pnas.org/content/117/33/19656">up to at least 2050</a>. Because of something called <a href="https://theconversation.com/siberia-heatwave-why-the-arctic-is-warming-so-much-faster-than-the-rest-of-the-world-141455">polar amplification</a> the Arctic will likely heat up by more than double the global average, with the climate models indicating around 8.3˚C warming over Greenland in the most extreme scenario, RCP8.5. </p>
<p>Despite this dramatic and terrifying hike in temperature Faezeh’s modelling study projected that the “big three” would contribute between 9 and 15 mm to sea level rise by 2100, only slightly more than what we obtained from a 1.5˚C warming over the 20th century. How can that be? Our conclusion is that the models are at fault, even including the <a href="https://tc.copernicus.org/articles/14/3071/2020/">latest and most sophisticated available</a> which are being used to assess how the whole ice sheet will respond to the next century of climate change. These models appear to have a relatively weak link between climate change and ice melt, when <a href="https://www.nature.com/articles/s41467-020-19580-5">our results</a> suggest it is much stronger. Projections based on these models are therefore likely to under-predict how much the ice sheet will be affected. Other lines of evidence <a href="https://theconversation.com/the-arctic-hasnt-been-this-warm-for-3-million-years-and-that-foreshadows-big-changes-for-the-rest-of-the-planet-144544">support</a> this <a href="https://theconversation.com/climate-change-sea-level-rise-could-displace-millions-of-people-within-two-generations-116753">conclusion</a>. </p>
<p>What does all of that mean? If we do continue along that very scary RCP8.5 trajectory of increasing greenhouse gas emissions, the Greenland ice sheet is very likely to start melting at rates that we haven’t seen for at least 130,000 years, with dire consequences for sea level and the <a href="https://www.nature.com/articles/s41467-019-12808-z">many millions of people</a> who live in low lying coastal zones.</p><img src="https://counter.theconversation.com/content/150261/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonathan Bamber receives funding from the UK Natural Environment Research Council and the European Research Council.</span></em></p>
Our new research shows the island’s largest glaciers are losing ice faster than previously thought.
Jonathan Bamber, Professor of Physical Geography, University of Bristol
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/144992
2020-10-05T12:10:13Z
2020-10-05T12:10:13Z
Shrinking glaciers have created a new normal for Greenland’s ice sheet – consistent ice loss for the foreseeable future
<figure><img src="https://images.theconversation.com/files/361421/original/file-20201002-20-8jxj4v.jpeg?ixlib=rb-1.1.0&rect=49%2C93%2C3603%2C2305&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">As Greenland's glaciers retreat, they are losing ice at a faster and faster rate. </span> <span class="attribution"><span class="source">Michalea King</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Greenland is the largest island on Earth, and about 80% of it is covered by a <a href="https://nsidc.org/cryosphere/quickfacts/icesheets.html">giant sheet of ice</a>. Slowly flowing glaciers connect this massive frozen reservoir of fresh water to the ocean, but because of climate change, these glaciers are rapidly retreating.</p>
<p><a href="https://scholar.google.com/citations?user=1PYqI-4AAAAJ&hl=en&oi=ao">I’m an earth scientist</a> who studies how changes to Greenland’s glaciers affect the stability of the ice sheet as a whole. Healthy glaciers are stable in size and shape and act as drains for the ice sheet, transporting ice into the sea. They maintain a balance where the ice added each year roughly equals the ice lost to the sea. </p>
<p>But because of warming caused by climate change, that dynamic has changed. </p>
<p>For years, scientists have watched as glaciers around the world retreat. But our research has found that the glaciers along the edge of Greenland have retreated so much that they no longer <a href="https://doi.org/10.1038/s43247-020-0001-2">keep the ice sheet that feeds them in balance</a>. </p>
<p>As the glaciers retreat up valleys, they flow faster and bring more ice from inland to the sea. Imagine a traffic jam: When a highway is jampacked with cars – or ice – it flows slowly. But as the jam or glacier gets smaller, the number of cars, or the amount of ice, that can flow by in a given time increases. </p>
<p>Greenland’s ice sheet is now out of balance. The new normal is an <a href="https://doi.org/10.1038/s43247-020-0001-2">annual overall loss of ice</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/361423/original/file-20201002-22-hnuk7b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An aerial view of the edge of the large Jakobshvan Glacier, where ice breaks off into the sea." src="https://images.theconversation.com/files/361423/original/file-20201002-22-hnuk7b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/361423/original/file-20201002-22-hnuk7b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/361423/original/file-20201002-22-hnuk7b.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/361423/original/file-20201002-22-hnuk7b.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/361423/original/file-20201002-22-hnuk7b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=524&fit=crop&dpr=1 754w, https://images.theconversation.com/files/361423/original/file-20201002-22-hnuk7b.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=524&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/361423/original/file-20201002-22-hnuk7b.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=524&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The place where glaciers meet the sea – called the calving front – is important for the stability of the entire ice sheet. Jakobshavn Glacier has been retreating for decades.</span>
<span class="attribution"><span class="source">Michalea King</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Changes at the edge, consequences for the whole</h2>
<p>Ice sheets are formed when snowfall accumulates over thousands of years and compresses into layers upon layers of ice. But ice is not a perfectly rigid material – it behaves kind of like an <a href="https://doi.org/10.1002/2015EF000301">extra-thick yet brittle honey</a>. </p>
<p>Once an ice sheet becomes tall enough, the ice begins to flow outward because of its own weight. This ice is funneled down valleys toward the ocean, forming fast–flowing outlet glaciers. These glaciers can move as much as <a href="https://doi.org/10.5194/tc-8-209-2014">10 miles</a> per year.</p>
<p>Although glaciers comprise only a narrow region at the edge of the ice sheet, they play a huge role in controlling how rapidly ice is drained from the sheet into the ocean. Generally, a glacier that extends a long distance through a valley <a href="https://doi.org/10.1029/JB094iB04p04071">will move more slowly</a> and drain less ice from the ice sheet than if it were shorter. </p>
<p>Most of Greenland’s glaciers end at the sea, where ocean water melts and weakens the ice until it breaks off in pieces that dramatically fall into the North Atlantic. If ice is lost at the front of the glacier faster than it is replenished by upstream ice, the glacier will recede inland. This is called glacial retreat. </p>
<p>Retreat not only shortens the length of the glacier but also reduces the <a href="https://doi.org/10.1038/ngeo394">friction between the ice and surrounding valleys</a>. With less surface area of ice touching the ground, the ice can flow faster. Much like a shrinking traffic jam, sustained glacier retreat results in faster-flowing glaciers that <a href="https://doi.org/10.3189/002214308786570908">drain the ice sheet above more rapidly</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/361422/original/file-20201002-13-1dijqh9.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map showing the extent of glacial retreat since 1990." src="https://images.theconversation.com/files/361422/original/file-20201002-13-1dijqh9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/361422/original/file-20201002-13-1dijqh9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=602&fit=crop&dpr=1 600w, https://images.theconversation.com/files/361422/original/file-20201002-13-1dijqh9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=602&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/361422/original/file-20201002-13-1dijqh9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=602&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/361422/original/file-20201002-13-1dijqh9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=757&fit=crop&dpr=1 754w, https://images.theconversation.com/files/361422/original/file-20201002-13-1dijqh9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=757&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/361422/original/file-20201002-13-1dijqh9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=757&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The blue line shows the current boundary between the Jakobshavn Glacier (right side, light gray) and the floating ice (center, white) between the valley walls (top and bottom, dark gray). The other colored lines show where this boundary was in previous years.</span>
<span class="attribution"><span class="source">Michalea King</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A persistent state of loss</h2>
<p>Ocean and air temperatures have strong effects on glaciers. Both <a href="https://doi.org/10.1029/2018GL078024">ocean</a> and <a href="https://doi.org/10.1007/s10712-013-9261-z">air temperatures</a> are rising.</p>
<p>For Greenland’s glaciers, the warming ocean is the biggest cause of glacial retreat. On average the glaciers have retreated about <a href="https://doi.org/10.1038/s43247-020-0001-2">3 kilometers since the mid-1980s</a>, with most of this retreat occurring between 2000 and 2005.</p>
<p>My colleagues and I used thousands of satellite images to measure changes in length, thickness and flow speed of Greenland’s glaciers. With this information, we found two important things: Glacial retreat is accelerating, and the ice sheet is losing an astonishing – and also increasing – amount of ice each year.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/361425/original/file-20201002-14-1td91n8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Michalea King, a glacier researcher, stands in front of bay full of icebergs." src="https://images.theconversation.com/files/361425/original/file-20201002-14-1td91n8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/361425/original/file-20201002-14-1td91n8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/361425/original/file-20201002-14-1td91n8.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/361425/original/file-20201002-14-1td91n8.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/361425/original/file-20201002-14-1td91n8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/361425/original/file-20201002-14-1td91n8.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/361425/original/file-20201002-14-1td91n8.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The glaciers have retreated so much that the amount of ice they lose exceeds how much ice is added each year.</span>
<span class="attribution"><span class="source">Santiago de la Peña</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our team found that today, the glaciers drain <a href="https://doi.org/10.1038/s43247-020-0001-2">14% more ice from the ice sheet annually</a> – approximately 500 billion metric tons – than they did on average between 1985 and 1999. This faster flow is causing the ice sheet that covers most of Greenland to shrink, but it has also changed the dynamic of the entire system. </p>
<p>The ice sheet is now in a new, unbalanced state of persistent mass loss. Before the year 2000, ice loss roughly equaled the ice added from snowfall, so the ice sheet was stable. Now, ice mass losses consistently exceed mass gains – even in the coolest years of relatively high snow accumulation. The glaciers used to act as an important traffic jam, keeping ice loss in check. Now, however, traffic flows more freely and the ice is able to more easily flow away from the ice sheet. </p>
<p>Unfortunately, warmer air temperatures have also <a href="https://doi.org/10.1038/s41586-018-0752-4">increased surface melt</a>, resulting in less snow now accumulating on Greenland. Given all these factors, my colleagues and I now estimate that the ice sheet may see a mass gain year <a href="https://doi.org/10.1038/s43247-020-0001-2">only once a century</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/361426/original/file-20201002-24-fwt0zp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An aerial view of a pond on the top of a glacier formed by melting ice." src="https://images.theconversation.com/files/361426/original/file-20201002-24-fwt0zp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/361426/original/file-20201002-24-fwt0zp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/361426/original/file-20201002-24-fwt0zp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/361426/original/file-20201002-24-fwt0zp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/361426/original/file-20201002-24-fwt0zp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=552&fit=crop&dpr=1 754w, https://images.theconversation.com/files/361426/original/file-20201002-24-fwt0zp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=552&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/361426/original/file-20201002-24-fwt0zp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=552&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eventually, the ice sheet will become completely landlocked, and only ice melt and snow accumulation will determine then whether it grows or disappears completely.</span>
<span class="attribution"><span class="source">Michalea King</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>In serious trouble, but not yet doomed</h2>
<p>Our study showed how widespread retreat drove both an increase in glacier discharge and a shift to persistent ice sheet mass loss. But this doesn’t mean the ice sheet is doomed. Continued retreat and further increases in discharge are limited by topography. </p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>Over the next several centuries, the glaciers may retreat onto higher ground and eventually form a completely <a href="https://doi.org/10.1126/sciadv.aav9396">landlocked ice sheet with minimal flow</a> – essentially a large chunk of ice sitting on top of Greenland with no glaciers to drain it. Under this future scenario, the balance of the ice sheet would be determined only by surface changes – snow accumulation and surface melt. This loss of ice would equal <a href="https://doi.org/10.1126/sciadv.aav9396">meters of sea level rise</a>.</p>
<p>At this point, the fate of the ice sheet simply depends on whether it is melting faster than it grows from snowfall. In a warm world where climate change is not addressed, the ice sheet will slowly melt and ultimately disappear. But if climate change is controlled and cooler temperatures are maintained for a prolonged period, it is possible that the Greenland ice sheet could regrow.
That day may be hundreds of years into the future, but it is actions made today that will decide the fate of Greenland’s ice sheet.</p><img src="https://counter.theconversation.com/content/144992/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michalea King received partial funding from NASA during her graduate studies to complete this work. </span></em></p>
Greenland’s glaciers have retreated so far that they can no longer support the ice sheet that feeds them. The ice sheet system has reached a new normal of consistent annual ice loss.
Michalea King, Postdoctoral Climate Science Researcher, The Ohio State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/144544
2020-09-30T12:27:39Z
2020-09-30T12:27:39Z
The Arctic hasn’t been this warm for 3 million years – and that foreshadows big changes for the rest of the planet
<figure><img src="https://images.theconversation.com/files/360342/original/file-20200928-22-p7w75v.jpg?ixlib=rb-1.1.0&rect=45%2C0%2C5100%2C3359&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ice floe drifting in Svalbard, Norway.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/ice-floe-drifting-in-the-hinlopenstretet-hinlopenstreet-news-photo/1265232693?adppopup=true">Sven-Erik Arndt/Arterra/Universal Images Group via Getty Images</a></span></figcaption></figure><p>Every year, sea ice cover in the Arctic Ocean shrinks to a low point in mid-September. This year it measures just 1.44 million square miles (3.74 million square kilometers) – the <a href="http://nsidc.org/arcticseaicenews/2020/09/arctic-sea-ice-decline-stalls-out-at-second-lowest-minimum/">second-lowest value</a> in the 42 years since satellites began taking measurements. The ice today covers only <a href="https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/">50% of the area it covered 40 years ago</a> in late summer.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/360368/original/file-20200928-18-7f937o.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph showing area of Arctic Ocean with at least 15% sea ice in 2020." src="https://images.theconversation.com/files/360368/original/file-20200928-18-7f937o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/360368/original/file-20200928-18-7f937o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=589&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360368/original/file-20200928-18-7f937o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=589&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360368/original/file-20200928-18-7f937o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=589&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360368/original/file-20200928-18-7f937o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=740&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360368/original/file-20200928-18-7f937o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=740&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360368/original/file-20200928-18-7f937o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=740&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This year’s minimum ice extent is the lowest in the 42-year-old satellite record except for 2012, reinforcing a long-term downward trend in Arctic ice cover. Each of the past four decades averages successively less summer sea ice.</span>
<span class="attribution"><span class="source">NSIDC</span></span>
</figcaption>
</figure>
<p>As the Intergovernmental Panel on Climate Change has shown, carbon dioxide levels in the atmosphere are <a href="https://www.ipcc.ch/srocc/">higher than at any time in human history</a>. The last time that atmospheric CO2 concentrations reached today’s level – <a href="https://www.esrl.noaa.gov/gmd/ccgg/trends/">about 412 parts per million</a> – was 3 million years ago, <a href="https://doi.org/10.5194/cp-15-1603-2019">during the Pliocene Epoch</a>. </p>
<p>As geoscientists who study <a href="https://www.semanticscholar.org/author/J.-Brigham-Grette/3965160">the evolution of Earth’s climate</a> and <a href="https://scholar.google.com/citations?user=vrffoAcAAAAJ&hl=en">how it creates conditions for life</a>, we see evolving conditions in the Arctic as an indicator of how climate change could transform the planet. If global greenhouse gas emissions continue to rise, they could return the Earth to Pliocene conditions, with higher sea levels, shifted weather patterns and altered conditions in both the <a href="https://doi.org/10.1073/pnas.1809600115">natural world</a> and <a href="https://doi.org/10.1126/sciadv.aaw1838">human societies</a>.</p>
<h2>The Pliocene Arctic</h2>
<p>We are part of a team of scientists who analyzed sediment cores from <a href="https://en.wikipedia.org/wiki/Lake_Elgygytgyn">Lake El’gygytgyn</a> in northeast Russia in 2013 to understand the Arctic’s climate under higher atmospheric carbon dioxide levels. Fossil pollen preserved in these cores shows that the Pliocene Arctic was very different from its current state. </p>
<p>Today the Arctic is a treeless plain with only sparse <a href="https://ucmp.berkeley.edu/exhibits/biomes/tundra.php">tundra vegetation</a>, such as grasses, sedges and a few flowering plants. In contrast, the Russian sediment cores contained <a href="https://doi.org/10.1126/science.1233137">pollen from trees such as larch, spruce, fir and hemlock</a>. This shows that <a href="https://ucmp.berkeley.edu/exhibits/biomes/forests.php">boreal forests</a>, which today end hundreds of miles farther south and west in Russia and at the Arctic Circle in Alaska, once reached all the way to the Arctic Ocean across much of Arctic Russia and North America. </p>
<p>Because the Arctic was much warmer in the Pliocene, the Greenland Ice Sheet did not exist. Small glaciers along Greenland’s mountainous eastern coast were among the few places with year-round ice in the Arctic. The Pliocene Earth had ice only at one end – in Antarctica – and that ice was <a href="https://dx.doi.org/10.1073%2Fpnas.1112248109">less extensive and more susceptible to melting</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/360318/original/file-20200928-22-1casktr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Forest with birches and evergreen trees." src="https://images.theconversation.com/files/360318/original/file-20200928-22-1casktr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/360318/original/file-20200928-22-1casktr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=903&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360318/original/file-20200928-22-1casktr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=903&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360318/original/file-20200928-22-1casktr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=903&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360318/original/file-20200928-22-1casktr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1134&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360318/original/file-20200928-22-1casktr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1134&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360318/original/file-20200928-22-1casktr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1134&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Boreal forest near Lake Baikal in Russia. Three million years ago these forests extended hundreds of miles farther north than they reach today.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Taiga#/media/File:BaikalForest_(pixinn.net).jpg">Christophe Meneboeuf/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Because the oceans were warmer and there were no large ice sheets in the Northern Hemisphere, sea levels were 30 to 50 feet (9 to 15 meters) higher around the globe than they are today. Coastlines were far inland from their current locations. The areas that are now California’s Central Valley, the Florida Peninsula and the Gulf Coast all were underwater. So was the land where major coastal cities like New York, Miami, Los Angeles, Houston and Seattle stand. </p>
<p>Warmer winters across what is now the western U.S. reduced snowpack, which these days <a href="https://theconversation.com/climate-change-will-mean-more-multiyear-snow-droughts-in-the-west-121406">supplies much of the region’s water</a>. Today’s Midwest and Great Plains were so much warmer and dryer that it would have been impossible to grow corn or wheat there. </p>
<h2>Why was there so much CO2 in the Pliocene?</h2>
<p>How did CO2 concentrations during the Pliocene reach levels similar to today’s? Humans would not appear on Earth for at least another million years, and our use of fossil fuels is even more recent. The answer is that some natural processes that have occurred on Earth throughout its history release CO2 to the atmosphere, while others consume it. The main system that keeps these dynamics in balance and controls Earth’s climate is a natural global thermostat, regulated by rocks that <a href="https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cycle">chemically react with CO2</a> and pull it out of the atmosphere.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/360392/original/file-20200928-18-10dxl29.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of rock thermostat" src="https://images.theconversation.com/files/360392/original/file-20200928-18-10dxl29.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/360392/original/file-20200928-18-10dxl29.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=341&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360392/original/file-20200928-18-10dxl29.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=341&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360392/original/file-20200928-18-10dxl29.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=341&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360392/original/file-20200928-18-10dxl29.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=428&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360392/original/file-20200928-18-10dxl29.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=428&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360392/original/file-20200928-18-10dxl29.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=428&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Greenhouse Effect leads to increases in surface temperatures and, in some places, rainfall. Together these accelerate silicate rock weathering. Faster weathering in turn removes more CO2 from the atmosphere (yellow arrow). The strength of the Greenhouse Effect relies on atmospheric CO2 levels.</span>
<span class="attribution"><span class="source">Gretashum/Wikipedia</span></span>
</figcaption>
</figure>
<p>In soils, certain rocks continually break down into new materials in reactions that consume CO2. These reactions tend to speed up when temperatures and rainfall are higher – exactly the climate conditions that occur when atmospheric greenhouse gas concentrations rise. </p>
<p>But this thermostat has a built-in control. When CO2 and temperatures increase and rock weathering accelerates, it pulls more CO2 from the atmosphere. If CO2 begins to fall, temperatures cool and rock weathering slows globally, pulling out less CO2. </p>
<p>Rock weathering reactions also can work faster where soil contains lots of newly exposed mineral surfaces. Examples include areas with high erosion or periods when Earth’s tectonic processes pushed land upward, creating major mountain chains with steep slopes. </p>
<p>The rock weathering thermostat operates at a geologically slow pace. For example, at the end of the Age of Dinosaurs about 65 million years ago, scientists estimate that atmospheric CO2 levels were between 2,000 and 4,000 parts per million. It took over 50 million years to reduce them naturally to around 400 parts per million in the Pliocene. </p>
<p>Because natural changes in CO2 levels happened very slowly, cyclic shifts in Earth’s climate system were also very slow. Ecosystems had millions of years to adapt, adjust and slowly respond to changing climates. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/2hNgEVFMJnQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Summer heat waves are altering northern Siberia, thawing permafrost and creating conditions for large-scale wildfires.</span></figcaption>
</figure>
<h2>A Pliocene-like future?</h2>
<p>Today human activities are overwhelming the natural processes that pull CO2 out of the atmosphere. At the dawn of the Industrial Era in 1750, atmospheric CO2 stood at about <a href="https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide">280 parts per million</a>. It has taken humans only 200 years to completely reverse the trajectory begun 50 million years ago and return the planet to CO2 levels not experienced for millions of years.</p>
<p>Most of that shift has happened since World War II. Yearly increases of 2-3 parts per million now are common. And in response, the Earth is warming at a fast pace. Since roughly 1880 the planet has warmed by <a href="https://earthobservatory.nasa.gov/world-of-change/global-temperatures">1 degree Celsius (2 degrees Fahrenheit)</a> – many times faster than any warming episode in the past 65 million years of Earth’s history. </p>
<p>In the Arctic, losses of reflective snow and ice cover have amplified this warming to +5 C (9 F). As a result, summertime Arctic sea ice coverage is trending lower and lower. Scientists project that the Arctic will be <a href="https://orcid.org/0000-0001-7316-8320">completely ice-free in summer</a> within the next two decades. </p>
<p>[<em>Insight, in your inbox each day.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=insight">You can get it with The Conversation’s email newsletter</a>.]</p>
<p>This isn’t the only evidence of drastic Arctic warming. Scientists have recorded <a href="https://nsidc.org/greenland-today/">extreme summer melt rates</a> across the Greenland Ice Sheet. In early August, Canada’s last remaining ice shelf, in the territory of Nunavut, <a href="https://www.nesdis.noaa.gov/content/canada%E2%80%99s-milne-ice-shelf-collapses">collapsed into the sea</a>. Parts of <a href="https://www.aljazeera.com/news/2020/07/07/siberian-arctic-experiences-record-high-temperatures/?gb=true">Arctic Siberia</a> and <a href="https://www.severe-weather.eu/news/svalbard-record-heat-norway-mk/">Svalbard</a>, a group of Norwegian islands in the Arctic Ocean, reached record-shattering high temperatures this summer. </p>
<p>Coastal cities, agricultural breadbasket regions and water supplies for many communities all will be radically different if this planet returns to a Pliocene CO2 world. This future is not inevitable – but avoiding it will require big steps now to decrease fossil fuel use and turn down Earth’s thermostat.</p><img src="https://counter.theconversation.com/content/144544/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julie Brigham-Grette receives funding from the US National Science Foundation </span></em></p><p class="fine-print"><em><span>Steve Petsch receives funding from the U.S. National Science Foundation. </span></em></p>
Extreme shrinkage of summer sea ice is just the latest evidence of rapid Arctic warming – and what happens in the Arctic doesn’t stay there.
Julie Brigham-Grette, Professor of Geosciences, UMass Amherst
Steve Petsch, Associate Professor of Geosciences, UMass Amherst
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/144575
2020-08-20T20:14:38Z
2020-08-20T20:14:38Z
We pieced together the most precise records of major climate events from thousands of years ago. Here’s what we found
<p>Between 115,000 and 11,700 years ago, the Earth would have been almost unrecognisable. Massive ice-sheets covered northern Europe and northern Asia, and about half of North America, and global sea-levels were as much as 130 meters lower than today.</p>
<p>In this period, known as the “last glacial period”, the climate was much cooler and drier than today. It was punctuated by some of the largest and most rapid climate change events in Earth’s recent geological history. </p>
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Read more:
<a href="https://theconversation.com/humans-inhabited-north-america-in-the-depths-of-the-last-ice-age-but-didnt-thrive-until-the-climate-warmed-142810">Humans inhabited North America in the depths of the last Ice Age, but didn't thrive until the climate warmed</a>
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<p>For a long time, scientists have pondered how closely timed these abrupt climate change events were between Greenland and other regions of the world — far beyond the Arctic.</p>
<p>In our research, <a href="https://science.sciencemag.org/cgi/doi/10.1126/science.aay5538">published today in Science</a>, we’ve shown abrupt climate changes across the Northern Hemisphere and into the southern mid-latitudes occurred simultaneously, within decades of each other, throughout the last glacial period. We’ve also determined exactly when the abrupt changes occurred, much more precisely than before. </p>
<p>This can help us predict how abrupt climate changes might play out in the future.</p>
<h2>A series of abrupt climate changes</h2>
<p>Scientists can peer into Earth’s climate history through long ice cylinders, called “<a href="http://www.iceandclimate.nbi.ku.dk/research/drill_analysing/">ice cores</a>”, drilled from the Greenland ice sheet. Changes in the chemical composition of these ice cores reveal that the surrounding atmospheric temperature repeatedly warmed by 8-16°C, and each time within just a few decades. </p>
<p>Each warming event was followed by a more gradual period of cooling. These abrupt warming and cooling events happened more than 25 times throughout the last glacial period, and are known as <a href="http://www.iceandclimate.nbi.ku.dk/research/climatechange/glacial_interglacial/the_glacial_instability/">Dansgaard-Oeschger events</a>. They reflect changes in circulation patterns of the Atlantic Ocean. </p>
<p>While we have records of climate changes from many regions, the relative timing of these changes between Greenland and across the northern hemisphere into the southern sub-tropics is not well understood. </p>
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Read more:
<a href="https://theconversation.com/6-000-years-of-climate-history-an-ancient-lake-in-the-murray-darling-has-yielded-its-secrets-133685">6,000 years of climate history: an ancient lake in the Murray-Darling has yielded its secrets</a>
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<p>This has been difficult to resolve because we need very precisely dated records to make exact comparisons in timing. Ice cores provide a wealth of information about Dansgaard-Oeschger events. But while they faithfully reproduce the patterns of past climate, they are difficult to date very precisely. </p>
<h2>Crystal time capsules beneath our feet</h2>
<p>For our study, we turned to more precisely datable climate records: those from cave <a href="https://www.climate.gov/news-features/featured-images/picture-climate-what-can-we-learn-caves">stalagmites</a>. </p>
<p>Stalagmites are cave mineral deposits, which build up layer-by-layer on the cave floor. Their growth is fed by water dripping from the cave ceiling, which carries with it a chemical signal of temperature and rainfall conditions above the cave at that time. This signal is trapped in the crystal structure of the growing stalagmite. </p>
<p><a href="https://earthobservatory.nasa.gov/features/Paleoclimatology_Speleothems">Stalagmites</a> can be dated very precisely, by measuring the decay of minute amounts of uranium trapped in them. This key feature enables us to compare the timing of climate events from place to place. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/353781/original/file-20200820-18-1p90z4x.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C994%2C666&q=45&auto=format&w=1000&fit=clip"><img alt="A group of stalagmites illuminated in a cave." src="https://images.theconversation.com/files/353781/original/file-20200820-18-1p90z4x.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C994%2C666&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353781/original/file-20200820-18-1p90z4x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353781/original/file-20200820-18-1p90z4x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353781/original/file-20200820-18-1p90z4x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353781/original/file-20200820-18-1p90z4x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353781/original/file-20200820-18-1p90z4x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353781/original/file-20200820-18-1p90z4x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Stalagmites hold chemical signals that reveal what the climate above the cave was like thousands of years ago.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>However, long, high-quality stalagmite records are rare. Scientists from around the world have been working for more than 20 years to produce these records. Only now that enough records are available, we are able to make precise comparisons of the timing of Dansgaard-Oeschger events between different regions.</p>
<p>We collated and compared 63 published stalagmite records from caves in Asia, Europe and South America, and we determined the timings of abrupt climate changes in each.</p>
<h2>What we found</h2>
<p>Our results show that during each Dansgaard-Oeschger event, climate changes felt in Asia, South America and Europe occurred within decades of one another. Being able to determine this level of synchrony is remarkable, given we are looking at events that occurred many tens of thousands of years ago. </p>
<p>This means that as large temperature increases were occurring in Greenland, abrupt changes were also occurring in air temperature and rainfall in Europe, and in the monsoon systems in Asia and South America.</p>
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Read more:
<a href="https://theconversation.com/delving-deep-into-caves-can-teach-us-about-climate-past-and-present-50122">Delving deep into caves can teach us about climate past and present</a>
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<p>So why is this important? First of all, finding that climate change events occurred in lots of different parts of the world within decades provides clues as to how they started in the first place.</p>
<p>It tells us the changes were likely propagated from the North Atlantic region to these locations through the re-organisation of patterns in atmospheric circulation. And knowing this can help scientists narrow down the underlying triggers, which are still not conclusive.</p>
<p>And our findings mean the precise ages from the stalagmites can be used to better date ice cores, enhancing one of the most important records we have of the last glacial climate.</p>
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<a href="https://images.theconversation.com/files/353783/original/file-20200820-16-nicg1f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An ice sheet over Greenland" src="https://images.theconversation.com/files/353783/original/file-20200820-16-nicg1f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353783/original/file-20200820-16-nicg1f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=329&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353783/original/file-20200820-16-nicg1f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=329&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353783/original/file-20200820-16-nicg1f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=329&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353783/original/file-20200820-16-nicg1f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=414&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353783/original/file-20200820-16-nicg1f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=414&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353783/original/file-20200820-16-nicg1f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=414&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">In the last glacial period, vast ice sheets covered much of the world.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<h2>Implications for the future</h2>
<p>The abrupt climate changes we studied occurred under very different conditions compared to the climate of today. </p>
<p>While our ancestors lived through the last glacial period, humans are unlikely to experience Dansgaard-Oeschger events for many thousands of years, until the earth has again cooled to glacial temperatures. </p>
<p>However, piecing together the puzzle of how abrupt climate changes took place in the past will help us to understand how abrupt climate changes might occur in the future. For example, our findings will help validate climate models used to predict climate changes.</p>
<p>Showing that profound changes in climate can occur simultaneously across large regions of the Earth highlights just how unstable and interconnected our climate system can be. </p>
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Read more:
<a href="https://theconversation.com/climate-explained-why-we-wont-be-heading-into-an-ice-age-any-time-soon-123675">Climate explained: why we won't be heading into an ice age any time soon</a>
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<img src="https://counter.theconversation.com/content/144575/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ellen Corrick received funding from The Australian Government Research Training Program. </span></em></p><p class="fine-print"><em><span>John Hellstrom received funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Russell Drysdale received funding from the Australian Research Council.</span></em></p>
The “last glacial period” saw huge, rapid climate changes. Our new research found they happened all around the world, and each time within just a few decades.
Ellen Corrick, PhD Candidate, The University of Melbourne
John Hellstrom, U-Series Geochemistry Specialist, The University of Melbourne
Russell Drysdale, Associate Professor , The University of Melbourne
Licensed as Creative Commons – attribution, no derivatives.