tag:theconversation.com,2011:/uk/topics/glaciers-1751/articlesGlaciers – The Conversation2024-03-05T21:00:26Ztag:theconversation.com,2011:article/2243732024-03-05T21:00:26Z2024-03-05T21:00:26ZFrozen in time: old paintings and new photographs reveal some NZ glaciers may soon be extinct<figure><img src="https://images.theconversation.com/files/579425/original/file-20240303-30-xkp27s.jpeg?ixlib=rb-1.1.0&rect=12%2C64%2C8502%2C3052&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Freshly exposed bedrock at the terminus of Brewster Glacier in March 2023.</span> <span class="attribution"><span class="source">Andrew Lorrey</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>As the austral summer draws to a close, we are preparing to fly over the Southern Alps to survey glaciers. This annual flight supports the longest scientific study of Aotearoa New Zealand’s icescapes – and it shows that all of our glaciers have retreated since 1978.</p>
<p>This year’s survey comes on the heels of the <a href="https://wmo.int/news/media-centre/wmo-confirms-2023-smashes-global-temperature-record">warmest year on record globally</a> and the <a href="https://niwa.co.nz/climate/summaries/annual-climate-summary-2023#">second warmest for New Zealand</a>, which produced extreme weather events and impacts that still cut deep for many local communities. </p>
<p>Despite strong El Niño conditions in the Pacific this season, which typically <a href="https://www.nature.com/articles/ncomms14202">boost ice volume</a>, we expect the recent heat grilling the glaciers will have had a grim effect. </p>
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<figcaption><span class="caption">Our work monitoring ice in the Southern Alps and central North Island shows many small glaciers are approaching an extinction horizon.</span></figcaption>
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<p>The 46-year record of end-of-summer glacier images is incredibly valuable because it contains irrefutable <a href="https://theconversation.com/a-birds-eye-view-of-new-zealands-changing-glaciers-97074">visual evidence of climate change</a>. We can see how glaciers are changing from year to year, with extremely hot years such as 2023 standing out clearly. </p>
<p>But our insights aren’t limited to images of glaciers taken from light aircraft. We can also learn from historic paintings of New Zealand’s mountain landscapes. </p>
<h2>Portraits of past climate</h2>
<p>Old paintings with glaciers are common for the European Alps, where many artists lived and visited. But similar offerings are relatively rare for our part of the world.</p>
<p>What’s remarkable for New Zealand is that some of these works of art were produced without the artist ever seeing the glaciers. </p>
<p>We recently scrutinised the artistic vistas painted by <a href="https://teara.govt.nz/en/biographies/1g25/gully-john">John Gully</a> to see if they were true to the real landscapes. Gully based his works on field sketches by <a href="https://teara.govt.nz/en/biographies/6h17/haast-julius-von">Julius Haast</a>, one of the first scientists to formerly recognise widespread glaciation in New Zealand. </p>
<p>Gully’s paintings show features that can be linked to glacial landforms we can see today, including moraines (rocks deposited by a glacier, typically at its edges), outwash fans (sediment deposited by braided rivers fed by a melting glacier) and trimlines (lines that mark a glacier’s earlier, higher position in a valley). </p>
<p>Many of those features in the paintings have ice in direct contact with them, showing how accurately field scientists and artists depicted glaciers at the time. </p>
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<a href="https://images.theconversation.com/files/578079/original/file-20240226-27-zie9ae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/578079/original/file-20240226-27-zie9ae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/578079/original/file-20240226-27-zie9ae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=305&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578079/original/file-20240226-27-zie9ae.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=305&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578079/original/file-20240226-27-zie9ae.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=305&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578079/original/file-20240226-27-zie9ae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=383&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578079/original/file-20240226-27-zie9ae.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=383&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578079/original/file-20240226-27-zie9ae.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=383&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">John Gully, On the Great Godley Glacier [1862], watercolour. Lakes and sediment now exist in these valleys where glaciers used to flow.</span>
<span class="attribution"><span class="source">Alexander Turnbull Library</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>Gully’s paintings were intended to convey the dramatic scale of a mysterious land located far away from industrialised 19th-century society. Serendipitously, for contemporary scientists, comparing these artworks with current photos vividly shows the magnitude of ice loss that has occurred since the mid-1800s. </p>
<p>The perspective we get from Gully’s paintings concurs with studies that place the <a href="https://www.science.org/doi/10.1126/science.1169312">timing of ice retreat</a> as being already underway in the mid-1800s. Prior to this time, known commonly as the Little Ice Age, New Zealand <a href="https://link.springer.com/article/10.1007/s00382-013-1876-8">experienced cooler temperatures</a> between about 1450 and 1850. </p>
<p>Modelling ice volume loss using these Little Ice Age landforms provides a benchmark. It illustrates that recent changes have occurred in a geological instant and that the <a href="https://www.nature.com/articles/s41598-020-70276-8">peak summer flows from glaciers</a> that helped create the braided river systems so typical of the South Island landscape are in the past. </p>
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Read more:
<a href="https://theconversation.com/how-climate-change-made-the-melting-of-new-zealands-glaciers-10-times-more-likely-143626">How climate change made the melting of New Zealand's glaciers 10 times more likely</a>
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<h2>Accelerating pace of glacier retreat</h2>
<p>Recent glacier changes are occurring ever more quickly. The long-term photographic record from the Southern Alps shows an <a href="https://www.cambridge.org/core/journals/journal-of-glaciology/article/southern-alps-equilibrium-line-altitudes-four-decades-of-observations-show-coherent-glacierclimate-responses-and-a-rising-snowline-trend/44DD090754DAEB558AFFF4D31BD734B1">acceleration</a> of the pace at which snowlines rise due to climate warming. </p>
<p>For a glacier to exist, average summer temperatures must be cool enough for the summer snowline to remain below mountain tops so ice can accumulate. We now observe that ice is disappearing from mountains which held small amounts during the late 1970s. Glaciers there are going extinct.</p>
<p>Combining long-term snowline observations with direct field measurements of <a href="https://www.antarcticglaciers.org/glacier-processes/mass-balance/#">glacier mass balance</a> and <a href="https://www.cambridge.org/core/journals/journal-of-glaciology/article/using-structure-from-motion-photogrammetry-to-measure-past-glacier-changes-from-historic-aerial-photographs/18ACF49DFC0EC82A02655108A9E3453C">3D models of ice volume change</a> gives a good synopsis of how things have changed and a sense of things to come. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/cop28-earths-frozen-zones-are-in-trouble-were-already-seeing-the-consequences-218119">COP28: Earth's frozen zones are in trouble – we're already seeing the consequences</a>
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<p>We estimate at least 13 trillion litres of water (in the form of ice) has been lost from the Southern Alps since 1978. This is equivalent to the basic water needs for all New Zealanders during that time. </p>
<p>The regions around the central Southern Alps that hold many small glaciers are experiencing accelerated ice loss. Some areas, like Southland and Otago, have small glaciers that are rapidly approaching an extinction horizon. And once they pass it, we are not likely to see them again. </p>
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<a href="https://images.theconversation.com/files/579415/original/file-20240303-18-6z9u00.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/579415/original/file-20240303-18-6z9u00.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579415/original/file-20240303-18-6z9u00.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=431&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579415/original/file-20240303-18-6z9u00.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=431&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579415/original/file-20240303-18-6z9u00.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=431&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579415/original/file-20240303-18-6z9u00.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=542&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579415/original/file-20240303-18-6z9u00.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=542&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579415/original/file-20240303-18-6z9u00.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=542&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">Brewster Glacier in Mt Aspiring National Park has the longest record of mass balance measurements. Using snowstakes, we document its retreat due to warming temperatures.</span>
<span class="attribution"><span class="source">Andrew Lorrey</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>The central North Island also hosts a number of <a href="https://www.rnz.co.nz/national/programmes/ourchangingworld/audio/2018783809/glaciers-as-barometers-of-climate-change54">small glaciers on Mt. Ruapehu</a> that feed into the headwaters of the Waikato and Whanganui rivers. Glaciers there were <a href="https://www.tandfonline.com/doi/abs/10.1080/00288306.2020.1811354">originally mapped</a> in the mid-20th century, and again in 1978, 1988 and 2016. A recent photographic capture of Mt Ruapehu reflects a dire situation, indicating glaciers are fast approaching extinction. </p>
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<a href="https://images.theconversation.com/files/579099/original/file-20240301-16-h982sz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/579099/original/file-20240301-16-h982sz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579099/original/file-20240301-16-h982sz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=706&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579099/original/file-20240301-16-h982sz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=706&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579099/original/file-20240301-16-h982sz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=706&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579099/original/file-20240301-16-h982sz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=887&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579099/original/file-20240301-16-h982sz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=887&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579099/original/file-20240301-16-h982sz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=887&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">This aerial image of the Mt Ruapehu summit region shows the earliest complete glacier survey from the Randolph Glacier Inventory (1978, white-dashed line) and an assessment from 2022 (yellow-dashed line).</span>
<span class="attribution"><span class="source">Shaun Eaves</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<h2>Environments and ethics</h2>
<p>New Zealand’s diminishing glaciers and loss of ice across Earth are largely carrying on unabated. These changes are primarily caused by rising temperatures driven by <a href="https://www.nature.com/articles/s41558-020-0849-2">human activities that produce greenhouse gas emissions</a>. </p>
<p>The <a href="https://gml.noaa.gov/ccgg/trends/weekly.html">global increase in atmospheric carbon dioxide</a> continues undiminished. This needs to change soon and rapidly to protect many of our glaciers. </p>
<p>We face particularly serious ethical questions with respect to Mt Ruapehu’s glaciers. They help sustain the Whanganui River Te Awa Tupua, which has been <a href="https://www.legislation.govt.nz/act/public/2017/0007/latest/whole.html">granted the rights of a living entity</a>. The glaciers’ ongoing retreat – and possible extinction – highlights our collective responsibilities for doing simultaneous harm to the environment and people.</p>
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<p><em>The authors acknowledge Rebekah Parsons-King at NIWA for her work on the Glacier Extinction Horizons video. We also thank Brian Anderson for his long-term leadership on the Brewster Glacier snowstakes programme, and Pascal Sirguey for his work calculating mass balance for Brewster Glacier.</em> </p>
<hr><img src="https://counter.theconversation.com/content/224373/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Lorrey receives funding from NIWA's Strategic Science Investment Fund, which supports the annual Southern Alps glacier and snowline survey. </span></em></p><p class="fine-print"><em><span>George Hook, Lauren Vargo, and Shaun Eaves do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>An estimated 13 trillion litres of ice has already been lost from glaciers in New Zealand’s Southern Alps since 1978. Several are now approaching extinction.Andrew Lorrey, Principal Scientist & Programme Leader of Southern Hemisphere Climates and Environments, National Institute of Water and Atmospheric ResearchGeorge Hook, Research Associate (in process), Canterbury MuseumLauren Vargo, Research Fellow, Antarctic Research Centre, Te Herenga Waka — Victoria University of WellingtonShaun Eaves, Senior Lecturer in Physical Geography, Te Herenga Waka — Victoria University of WellingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2232412024-02-12T16:03:49Z2024-02-12T16:03:49ZNature award for polar bear photo shows that images of these magnificent creatures still have the power to move people<p>A polar bear sleeps perched atop a precariously angled shard of melting ice. The bear’s calm is juxtaposed by the frenetic waves lapping at the little island, suggesting that at some point the sea will reclaim it. This is the scene, captured by the photographer Nima Sarikhani, that <a href="https://www.bbc.co.uk/news/in-pictures-68215592">has won</a> this year’s Wildlife Photographer of the Year People’s Choice award. </p>
<p>When I saw this picture had won, I had mixed feelings. </p>
<p>Don’t get me wrong, the photograph is stunning and fully deserves praise. But the subject of a lone bear on a small patch of ice remains, for me, laden with problems. In the 2015 film <a href="https://www.youtube.com/watch?v=MOG6umLGFs8">This Changes Everything</a>, the writer Naomi Klein famously stated that images of “desperate polar bears” were so regularly used in the media that they had begun to bore her. </p>
<p>She didn’t mean that she didn’t care but wanted to draw attention to the way that certain images or motifs lose power the more they are repeated. Was it useful for the environmental movement to keep fixating on polar bears when countless other species were also suffering or when there are, perhaps, more original ways of communicating the issues at hand?</p>
<p>Up until recently, I’d been persuaded by Klein’s argument. Popular messaging around climate change is saturated with images of polar bears and it can be hard to maintain interest. However, that Sarikhani’s photograph received the People’s Choice award is one of many indications that the power of the polar bear is not as diminished as some think it is. Was I wrong to be bored of polar bears?</p>
<p>About a year ago, I started approaching this question from another angle by looking at how polar bears have been depicted in the past.</p>
<h2>Beyond photographs</h2>
<p>As an expert on 19th-century art and visual culture, I’ve frequently encountered polar bears in <a href="https://artuk.org/discover/artworks/the-cold-north-124946/search/2024--keyword:polar-bear--referrer:global-search/page/2/view_as/grid">Victorian paintings</a>, yet I hadn’t given them a second thought.</p>
<p>I decided to explore whether there was a connection between these historical works and our current fascination. I also wanted to look beyond a certain way of visualising polar bears. After all, Klein’s reservations were not about polar bears per se, but about images of “desperate” polar bears. Perhaps there are other ways of picturing them that might change the way I thought.</p>
<p>My research took me on a fascinating journey, from delicate <a href="https://collectionsearch.pkc.gov.uk/detail.aspx?parentpriref=">Innuit sculptures</a> of standing bears to some <a href="https://forbesandclark.mused.org/en/items/7271/greenland-whale-fishery">rather dodgy European prints</a> in which they look rather more like white, shaggy dogs. </p>
<p>Through these works, I’ve learned a lot about the long and complex relationship between people and polar bears, and how polar bears have been constantly caught up in wider concerns. For example, Edwin Landseer’s famous 1864 painting <a href="https://www.royalholloway.ac.uk/about-us/art-collections/collection-highlights/man-proposes-god-disposes/#:%7E:text=This%20painting%20of%20two%20polar,find%20the%20North%2DWest%20passage.">Man Proposes, God Disposes</a> represents two ferocious bears feeding among the wreckage of a ship. </p>
<p>Man Proposes, God Disposes is about the arctic explorer <a href="https://theconversation.com/hms-terror-wreck-found-but-what-happened-to-her-doomed-crew-heres-the-science-65384">John Franklin’s famous failed expedition</a> to discover the Northwest Passage. Here, the polar bears represent man’s violent defeat by nature.</p>
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<img alt="Painting of two polar bears feeding among the wreckage of a ship in the arctic." src="https://images.theconversation.com/files/574949/original/file-20240212-24-ej4mrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574949/original/file-20240212-24-ej4mrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=220&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574949/original/file-20240212-24-ej4mrv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=220&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574949/original/file-20240212-24-ej4mrv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=220&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574949/original/file-20240212-24-ej4mrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=276&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574949/original/file-20240212-24-ej4mrv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=276&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574949/original/file-20240212-24-ej4mrv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=276&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Man Proposes God Disposes by Edwin Landseer.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Man_Proposes,_God_Disposes#/media/File:Manproposesgoddisposes.jpg">Wikimedia</a></span>
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<p><a href="https://artuk.org/discover/artworks/diana-and-chase-in-the-arctic-79330">Other Victorian paintings</a>, meanwhile, show how closely the fate of polar bears was aligned to the whaling trade in and around the north and south poles. When whales became scarce in Arctic waters, hunters would turn their attention to the trade in bear skins. Here, man’s dependence on nature is foregrounded as well as the violence enacted upon it.</p>
<p>While researching these pictures I decided to reach out to Doug Allan, a wildlife cameraman who has spent over 35 years filming and photographing in the Arctic. I wanted to know whether Allan could see connections between the longer history of polar bear imagery and contemporary photographs and footage of bears we see today.</p>
<h2>Better stories</h2>
<p>It’s fair to say that Allan has never been bored of polar bears, despite the many hours he has spent in the Arctic waiting for one to amble into view. </p>
<p>He shared my interest in the history of polar bears and the contexts in which their image has been used. Together, we explored the collections in the Scottish city of Perth. Objects owned by Perth Museum and Art Gallery and the Royal Scottish Geographical Society, offered me new insights into this subject.</p>
<p>We drew links between 19th-century paintings and the kind of footage he’s filmed for series such as <a href="https://www.bbc.co.uk/programmes/b00mfl7n">Frozen Planet</a>. Although there are many differences, these Victorian paintings and nature documentaries share the goal of trying to capture moments of high drama to communicate a message.</p>
<p>The conclusion we reached was that it wasn’t pictures of polar bears that were boring, the problem was the limited, often maudlin narratives that accompanied them. The images are more than cute, sad or emotional representations of climate collapse – these sorts of descriptions flatten them. Instead, they deserve explanations that tell much more complex, sometimes conflicted stories.</p>
<p>In relation to this, I’m still thinking about Sarikhan’s photograph – about how it differs from other contemporary polar bear images and may relate to this longer tradition of depicting bears.</p>
<iframe width="100%" height="315" src="https://www.youtube.com/embed/M7iAFsAzzk8?si=bDh5FecHL9oE8bjh" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen=""></iframe>
<p>Why are photos of polar bears on icebergs so popular? What other kinds of polar images are we overlooking? How would our perception of this particular photograph differ, for instance, if the bear were dead, not sleeping?</p>
<p>I may have mixed feelings about Sarikhan’s photograph. However, as someone who has now seen hundreds of images of polar bears, I am far from bored by it. Instead, when I look at it, I see the complex history of polar bear images and the many dramatic narratives of survival and violence that have continuously been thrust upon them.</p>
<p>So, if you are feeling unmoved by what you consider “just another bear on an iceberg” try thinking about the storied tradition of polar bear images, about how these have changed as our own relationship with the environment has, and I dare you to be bored.</p><img src="https://counter.theconversation.com/content/223241/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samuel Shaw has in the past received funding from the Arts and Humanities Research Council</span></em></p>Image of the majestic creatures remain powerful communicators of humanity’s connection with nature.Samuel Shaw, Lecturer in History of Art, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2228342024-02-09T19:01:37Z2024-02-09T19:01:37ZAtlantic Ocean is headed for a tipping point − once melting glaciers shut down the Gulf Stream, we would see extreme climate change within decades, study shows<figure><img src="https://images.theconversation.com/files/573965/original/file-20240207-22-751n5r.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5607%2C3741&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Too much fresh water from Greenland's ice sheet can slow the Atlantic Ocean's circulation.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/iceberg-calving-from-eqip-glacier-on-disko-bay-royalty-free-image/534972902?phrase=melting+glaciers+greenland&adppopup=true">Paul Souders/Stone via Getty Images</a></span></figcaption></figure><p>Superstorms, abrupt climate shifts and New York City frozen in ice. That’s how the blockbuster Hollywood movie “<a href="https://www.imdb.com/title/tt0319262/">The Day After Tomorrow</a>” depicted an abrupt shutdown of the Atlantic Ocean’s circulation and the catastrophic consequences.</p>
<p>While Hollywood’s vision was over the top, the 2004 movie raised a serious question: If global warming shuts down the Atlantic Meridional Overturning Circulation, which is crucial for carrying heat from the tropics to the northern latitudes, how abrupt and severe would the climate changes be?</p>
<p>Twenty years after the movie’s release, we know a lot more about the Atlantic Ocean’s circulation. Instruments deployed in the ocean starting in 2004 <a href="http://dx.doi.org/10.1038/s41586-018-0006-5">show that the Atlantic Ocean circulation</a> has <a href="https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/">observably slowed</a> over the past two decades, possibly to its <a href="https://doi.org/10.1038/s41561-021-00699-z">weakest state in almost a millennium</a>. Studies also suggest that the circulation has reached a <a href="https://doi.org/10.1126/science.abn7950">dangerous tipping point</a> in <a href="https://doi.org/10.1126/science.aaf5529">the past</a> that sent it into a precipitous, unstoppable decline, and that it <a href="https://doi.org/10.1038/s41467-023-39810-w">could hit that tipping point again</a> as the planet warms and glaciers and ice sheets melt.</p>
<p>In a new study using the latest generation of Earth’s climate models, we simulated the flow of fresh water until the ocean circulation reached that tipping point. </p>
<p>The results showed that the circulation could <a href="http://www.science.org/doi/10.1126/sciadv.adk1189">fully shut down within a century</a> of hitting the tipping point, and that it’s headed in that direction. If that happened, average temperatures would drop by several degrees in North America, parts of Asia and Europe, and people would see severe and cascading consequences around the world.</p>
<p>We also discovered a physics-based early warning signal that can alert the world when the Atlantic Ocean circulation is nearing its tipping point.</p>
<h2>The ocean’s conveyor belt</h2>
<p>Ocean currents are driven by winds, tides and water <a href="https://doi.org/10.1007/s003820050144">density differences</a>.</p>
<p>In the Atlantic Ocean circulation, the relatively warm and salty surface water near the equator flows toward Greenland. During its journey it crosses the Caribbean Sea, loops up into the Gulf of Mexico, and then flows along the U.S. East Coast before crossing the Atlantic. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two illustrations show how the AMOC looks today and its weaker state in the future" src="https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How the Atlantic Ocean circulation changes as it slows.</span>
<span class="attribution"><a class="source" href="https://www.ipcc.ch/report/ar6/wg1/figures/chapter-9/faq-9-3-figure-1">IPCC 6th Assessment Report</a></span>
</figcaption>
</figure>
<p>This current, also known as the Gulf Stream, brings heat to Europe. As it flows northward and cools, the water mass becomes heavier. By the time it reaches Greenland, it starts to sink and flow southward. The sinking of water near Greenland pulls water from elsewhere in the Atlantic Ocean and the cycle repeats, like a <a href="https://doi.org/10.1002/2015RG000493">conveyor belt</a>.</p>
<p><a href="https://doi.org/10.1126/science.abn7950">Too much fresh water</a> from melting glaciers and the Greenland ice sheet can dilute the saltiness of the water, preventing it from sinking, and weaken this <a href="https://doi.org/10.1002/2015RG000493">ocean conveyor belt</a>. A <a href="https://doi.org/10.1073/pnas.97.4.1347">weaker conveyor belt</a> transports <a href="https://doi.org/10.1038/s41558-022-01380-y">less heat northward</a> and also enables less heavy water to reach Greenland, which <a href="https://doi.org/10.1073/pnas.97.4.1347">further weakens</a> the conveyor belt’s strength. Once it reaches the <a href="https://doi.org/10.1073/pnas.0705414105">tipping point</a>, it shuts down quickly.</p>
<h2>What happens to the climate at the tipping point?</h2>
<p>The existence of a tipping point was first noticed in an overly simplified model of the Atlantic Ocean circulation in the <a href="https://doi.org/10.1111/j.2153-3490.1961.tb00079.x">early 1960s</a>. Today’s more <a href="https://www.carbonbrief.org/cmip6-the-next-generation-of-climate-models-explained/">detailed climate models</a> indicate a continued <a href="https://doi.org/10.1029/2019GL086075">slowing of the conveyor belt’s strength</a> under climate change. However, an abrupt shutdown of the Atlantic Ocean circulation <a href="https://doi.org/10.1016/j.physd.2023.133984">appeared to be absent</a> in these climate models.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/p4pWafuvdrY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How the ocean conveyor belt works.</span></figcaption>
</figure>
<p>This is where our study comes in. We performed an experiment with a detailed climate model to find the tipping point for an abrupt shutdown by slowly increasing the input of fresh water. </p>
<p>We found that once it reaches the tipping point, the conveyor belt shuts down within 100 years. The heat transport toward the north is strongly reduced, leading to abrupt climate shifts.</p>
<h2>The result: Dangerous cold in the North</h2>
<p>Regions that are influenced by the Gulf Stream receive <a href="https://doi.org/10.1038/s41558-022-01380-y">substantially less heat</a> when the circulation stops. This cools the North American and European continents by a few degrees.</p>
<p>The European climate is much more influenced by the Gulf Stream than other regions. In our experiment, that meant parts of the continent changed at more than 5 degrees Fahrenheit (3 degrees Celsius) per decade – far faster than today’s global warming of about 0.36 F (0.2 C) per decade. We found that parts of Norway would experience temperature drops of more than 36 F (20 C). On the other hand, regions in the Southern Hemisphere would warm by a few degrees.</p>
<figure class="align-center ">
<img alt="Two maps show US and Europe both cooling by several degrees if the AMOC stops." src="https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=271&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=271&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=271&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=340&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=340&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=340&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The annual mean temperature changes after the conveyor belt stops reflect an extreme temperature drop in northern Europe in particular.</span>
<span class="attribution"><a class="source" href="http://www.science.org/doi/10.1126/sciadv.adk1189">René M. van Westen</a></span>
</figcaption>
</figure>
<p>These temperature changes develop over about 100 years. That might seem like a long time, but on typical climate time scales, it is abrupt.</p>
<p>The conveyor belt shutting down would also affect sea level and precipitation patterns, which can <a href="https://doi.org/10.1088/1748-9326/ac3955">push other ecosystems closer to their tipping points</a>. For example, the Amazon rainforest is vulnerable to <a href="https://doi.org/10.1073/pnas.2120777119">declining precipitation</a>. If its forest ecosystem turned to grassland, the transition would <a href="https://esd.copernicus.org/articles/13/1667/2022/">release carbon</a> to the atmosphere and result in the loss of a valuable carbon sink, further accelerating climate change.</p>
<p>The Atlantic circulation has <a href="https://doi.org/10.1126/science.aaf5529">slowed significantly in the distant past</a>. During <a href="https://doi.org/10.1146/annurev-marine-010816-060415">glacial periods</a> when ice sheets that covered large parts of the planet were melting, the influx of fresh water slowed the Atlantic circulation, triggering huge climate fluctuations.</p>
<h2>So, when will we see this tipping point?</h2>
<p>The big question – when will the Atlantic circulation reach a tipping point – remains unanswered. Observations don’t go back far enough to provide a clear result. While a recent study suggested that the conveyor belt is rapidly <a href="https://doi.org/10.1038/s41467-023-39810-w">approaching its tipping point</a>, possibly within a few years, these statistical analyses made several assumptions that give rise to uncertainty.</p>
<p>Instead, we were able to develop a physics-based and observable early warning signal involving the salinity transport at the southern boundary of the Atlantic Ocean. Once a threshold is reached, the tipping point is likely to follow in one to four decades.</p>
<figure class="align-center ">
<img alt="A line chart of circulation strength shows a quick drop-off after the amount of freshwater in the ocean hits a tipping point." src="https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=467&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=467&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=467&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=586&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=586&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=586&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A climate model experiment shows how quickly the AMOC slows once it reaches a tipping point with a threshold of fresh water entering the ocean. How soon that will happen remains an open question.</span>
<span class="attribution"><a class="source" href="http://www.science.org/doi/10.1126/sciadv.adk1189">René M. van Westen</a></span>
</figcaption>
</figure>
<p>The climate impacts from our study underline the severity of such an abrupt conveyor belt collapse. The temperature, sea level and precipitation changes will severely affect society, and the <a href="https://doi.org/10.1029/2023GL106088">climate shifts are unstoppable</a> on human time scales.</p>
<p>It might seem counterintuitive to worry about extreme cold as the planet warms, but if the main Atlantic Ocean circulation shuts down from too much meltwater pouring in, that’s the risk ahead.</p>
<p><em>This article was updated on Feb. 11, 2024, to fix a typo: The experiment found temperatures in parts of Europe changed by more than 5 F per decade.</em></p><img src="https://counter.theconversation.com/content/222834/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>René van Westen receives funding from the European Research Council (ERC-AdG project 101055096, TAOC).</span></em></p><p class="fine-print"><em><span>Henk A. Dijkstra receives funding from the European Research Council (ERC-AdG project 101055096, TAOC, PI: Dijkstra). </span></em></p><p class="fine-print"><em><span>Michael Kliphuis 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>Scientists now have a better understanding of the risks ahead and a new early warning signal to watch for.René van Westen, Postdoctoral Researcher in Climate Physics, Utrecht UniversityHenk A. Dijkstra, Professor of Physics, Utrecht UniversityMichael Kliphuis, Climate Model Specialist, Utrecht UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2182012024-01-19T13:41:44Z2024-01-19T13:41:44ZI’m an artist using scientific data as an artistic medium − here’s how I make meaning<figure><img src="https://images.theconversation.com/files/569152/original/file-20240112-27-8u7iv7.jpeg?ixlib=rb-1.1.0&rect=2%2C0%2C1393%2C932&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sarah Nance at the Bonneville Salt Flats, Utah, 2019.</span> <span class="attribution"><span class="source">Courtesy of Sarah Nance</span></span></figcaption></figure><p>As an <a href="https://www.binghamton.edu/art/profile.html?id=snance">artist working across media</a>, I’ve used everything from thread to my voice to poetically translate and express information. Recently, I’ve been working with another medium – geologic datasets. </p>
<p>While scientists use data visualization to show the results of a dataset in interesting and informative ways, my goal as an artist is a little different. In the studio, I treat geologic data as another material, using it to guide my interactions with Mylar film, knitting patterns or opera. Data, in my work, functions expressively and abstractly. </p>
<p>Two of my projects in particular, “points of rupture” and “tidal arias,” exemplify this way of working. In these pieces, my goal is to offer new ways for people to personally relate to the immense scale of geologic time.</p>
<h2>Points of rupture</h2>
<p>An early project in which I treated data as a medium was my letterpress print series “<a href="https://www.sarahnance.com/shroud/alaska">points of rupture</a>.” In this series, I encoded data from <a href="https://www.britannica.com/science/cryoseism">cryoseismic, or ice quake</a>, events to create knitting patterns. </p>
<p>Working with ice quake data was a continuation of my research into what I call “archived landscapes.” These are places that have had multiple distinct geologic identities over time, like <a href="https://www.nps.gov/gumo/learn/nature/coralreefs.htm">mountains that were once sea reefs</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="silver knitting symbols on black background" src="https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.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"></a>
<figcaption>
<span class="caption">‘points of rupture (alaska glacial event 1999),’ 2020. Letterpress print of knitting pattern coded using cryoseismic data. Edition of 15. 18 x 18 in.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p>Because knit textiles are made up of many individual stitches, I can use them to encode discrete data points. In a knitting pattern, or chart, each kind of stitch is represented by a specific symbol. I used the open-source program <a href="https://stitch-maps.com">Stitch Maps</a> to write the patterns for this project, translating the peaks and valleys of seismographs into individual stitch symbols. </p>
<p>Knitting charts typically display these symbols in a grid. Instead, Stitch Maps allows them to fall as they would when knitted, so the chart mimics the shape of the final textile. </p>
<p>I was drawn to the expressive possibilities of this feature and how the software allowed me to experiment. I was able to write patterns that worked only in theory and not as physical, handmade structures. This gave me more freedom to design patterns that fully expressed the datasets without having to ensure their viability as textiles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="graphite drawing of mitten knitting chart on gallery wall" src="https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.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">‘and when you change the landscape, is it with bare hands or with gloves? (lichen, woodwork, grate),’ 2023. Graphite drawing of selbu mitten knitting chart. 99 x 67 linear inches as installed.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p><a href="https://nsidc.org/learn/parts-cryosphere/glaciers">Glaciers form</a> incrementally as new snowfall compacts previous layers of snow, crystallizing them into ice. A knitted fabric similarly accumulates in layers, as rows of interlocking loops. Each structure appears stable but could easily be dissolved.</p>
<p>Ice quakes occur in glaciers as a result of <a href="https://www.britannica.com/science/cryoseism">calving events or pooling meltwater</a>. Like melting glaciers, knitting is always in danger of coming apart – but instead of melting, by snagging and unraveling into formlessness. These structural similarities between glaciers and knitting are reflected in the “points of rupture” prints, where disruptive ice quakes translate into unknittable patterns. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="silver knitting symbols on black background" src="https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.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"></a>
<figcaption>
<span class="caption">‘points of rupture (glacier de la plaine morte icequake 2016),’ 2020. Letterpress print of knitting pattern coded using cryoseismic data. Edition of 15. 18 x 18 in.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<h2>The loop</h2>
<p>Repeated, interlocking loops are the base units that compose the structure of a knitted textile. The loop also forms the seed of an in-progress work I pursued during an artist residency with the <a href="https://lunarscience.nasa.gov/sserviteams">NASA</a> <a href="https://www.geodes.umd.edu">GEODES</a> research group. I joined their research team in Flagstaff, Arizona, in August 2023. I assisted in gathering data from sites within the San Francisco volcanic field, while also conducting my own fieldwork: photography, drawing, note-taking and walking.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A digital map showing a crater, with a green circle indicating the path walked, around the lip of the crater." src="https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=629&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=629&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=629&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=790&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=790&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=790&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sarah Nance’s walk at S P Crater in Arizona, as recorded in AllTrails.</span>
<span class="attribution"><span class="source">Screenshot of All Trails map</span></span>
</figcaption>
</figure>
<p>One of my walks was a trek around a particularly prominent geologic loop – the rim of the S P cinder cone volcano. This is the second crater walk I’ve completed, the first being a tracing of the subsurface rim of the <a href="https://insider.si.edu/2013/03/iowa-meteorite-crater-confirmed/">Decorah impact structure</a> in Iowa. </p>
<p>I see my paths through these landscapes as stand-ins for yarn. Over time, by taking walks that trace craters, or geologic loops, I will perform a textile. The performance of something as familiar as a textile offers me a new way to think about something that is much more difficult to comprehend – <a href="https://www.britannica.com/science/geologic-time">geologic time</a>. </p>
<hr>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A square box with the words 'Art & Science Collide' and a drawing of a lightbulb with its wire filament in the shape of a brain, surrounded by a circle." src="https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.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"></a>
<figcaption>
<span class="caption">Art & Science Collide series.</span>
<span class="attribution"><span class="source">source</span></span>
</figcaption>
</figure>
<p><em><strong><a href="https://theconversation.com/us/topics/art-in-science-series-2024-149583">This article is part of Art & Science Collide</a></strong>, a series examining the intersections between art and science.</em></p>
<p><em>You may be interested in:</em></p>
<p><a href="https://theconversation.com/literature-inspired-my-medical-career-why-the-humanities-are-needed-in-health-care-217357">Literature inspired my medical career: Why the humanities are needed in health care</a></p>
<p><a href="https://theconversation.com/i-wrote-a-play-for-children-about-integrating-the-arts-into-stem-fields-heres-what-i-learned-about-encouraging-creative-interdisciplinary-thinking-218001">I wrote a play for children about integrating the arts into STEM fields – here’s what I learned about interdisciplinary thinking</a> </p>
<p><a href="https://theconversation.com/art-and-science-entwined-this-course-explores-the-long-interrelated-history-of-two-ways-of-seeing-the-world-210250">Art and science entwined: This course explores the long, interrelated history of two ways of seeing the world </a></p>
<hr>
<h2>Performance and tides</h2>
<p>Performance has been a useful tool in my work, as it can help people understand and relate to geologic processes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="artist's hands holding small chunk of glacial ice" src="https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.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">‘transference,’ 2017. Atlantic sea ice, body heat. Documentation of site-responsive performance on the East Coast Trail, Newfoundland, Canada. Project supported in part by La Soupée, Galerie Diagonale, Montréal, Québec.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p>The field of geology emerges from a <a href="https://www.upress.umn.edu/book-division/books/a-billion-black-anthropocenes-or-none">long history</a> of extraction and <a href="https://www.dukeupress.edu/geontologies">colonialist ventures</a>. In this context, land is valued for its economic importance – as raw material to be extracted or territory to be claimed. In my performances, I aim to interact with geology as its own active entity, rather than as a consumable resource. </p>
<p>In recent years, I have composed and performed two arias from tidal data. </p>
<p>The first, “<a href="https://www.sarahnance.com/marseille">marseille tidal gauge aria</a>,” sourced 130 years of sea level data collected from a tidal gauge in the Bay of Marseille, France. I converted each yearly average sea level into an individual note within my vocal range. This resulted in a composition that expresses the rising sea levels of the bay as increasingly higher pitches in the aria. </p>
<p>Its lyrics come from a somber poem in Rasu-Yong Tugen’s book “<a href="https://gnomebooks.wordpress.com/2014/02/10/songs-from-the-black-moon/">Songs From the Black Moon</a>.” Each note of the aria communicates not just the measured sea level but also my emotive response to this dataset. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Black flexi disc with gold text and image" src="https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.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">‘tidal arias,’ 2022. Limited edition flexi disc with vocal performances ‘marseille tidal gauge aria’ and ‘skagway tidal aria.’</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p>Last fall, “marseille tidal gauge aria” was transmitted <a href="https://www.swpc.noaa.gov/phenomena/ionosphere">to the ionosphere</a>, the boundary between Earth’s atmosphere and outer space. This was done as part of artist Amanda Dawn Christie’s project “<a href="https://ghostsintheairglow.space/transmission/august-2023">Ghosts in the Air Glow</a>,” using the <a href="https://haarp.gi.alaska.edu">High-frequency Active Auroral Research Program</a>’s ionospheric research instrument, which is an array of 180 antennas transmitting high-frequency radio waves. </p>
<p>The aria’s transmission reflected off the ionosphere, back to Earth and to shortwave radio listeners around the world.</p>
<p>For the second of these vocal pieces, “skagway tidal aria,” I used predictive as well as recorded tidal data from Skagway, Alaska. With this data, I composed an aria for <a href="https://t2051mcc.com">The 2051 Munich Climate Conference</a>, where speakers presented from the perspective of a climate-altered world 30 years in the future. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="vocal music score" src="https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Score for ‘skagway tidal aria,’ 2021. Recorded and speculative tidal data from Skagway, Alaska (1945-2081), sonified as a vocal composition. Text from ‘Songs From the Black Moon’ by Rasu-Yong Tugen.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p>I was drawn to this particular dataset because the falling tide levels in Skagway appear to contradict the <a href="https://theconversation.com/what-drives-sea-level-rise-us-report-warns-of-1-foot-rise-within-three-decades-and-more-frequent-flooding-177211">global trend of rising sea levels</a>. However, this is a temporary effect caused by melting glaciers releasing pressure on the land, allowing it to rise faster than water levels. The effect will flatten over the next half-century, and Skagway’s tides will start to rise again.</p>
<p>Over the next few months, I’ll be working with geophysical datasets gathered during the NASA GEODES field expedition to write new arias. I want these pieces to continue blurring the separation between the human and the geologic, inviting listeners to think more deeply about their own relationships with the lands they use and occupy.</p><img src="https://counter.theconversation.com/content/218201/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The author's projects with GEODES and Ghosts in the Air Glow were supported with funding from these organizations.</span></em></p>Sarah Nance uses geologic data and a variety of artistic media to help people think about their place in the landscapes they use and occupy.Sarah Nance, Assistant Professor of Integrated Practice in Art and Design, Binghamton University, State University of New YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2195332023-12-13T17:19:17Z2023-12-13T17:19:17ZAntarctic study proves glacier has undergone irreversible retreat – highlighting potential for widespread ice loss<figure><img src="https://images.theconversation.com/files/565184/original/file-20231212-19-asy8hd.JPG?ixlib=rb-1.1.0&rect=0%2C418%2C2437%2C1880&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ice on the Antarctic peninsula flowing along a channel into an ice shelf in the ocean.</span> <span class="attribution"><span class="source">Hilmar Gudmundsson</span></span></figcaption></figure><p><a href="https://www.antarcticglaciers.org/antarctica-2/west-antarctic-ice-sheet-2/pine-island-glacier/">Pine Island glacier</a> is one of the fastest flowing outlets of ice from the west <a href="https://www.pnas.org/doi/abs/10.1073/pnas.1812883116">Antarctic ice sheet</a>, draining an area three-quarters the size of the UK. In recent decades, the glacier has been retreating rapidly and losing ice, contributing more to global sea level rise than any other Antarctic glacier. </p>
<p>The speed of the glacier’s retreat and the rate that is has been losing ice has led to concerns about how stable the region is. <a href="https://tc.copernicus.org/articles/17/3761/2023/">Model results show</a> that this region of west Antarctica could collapse in the future. If it does, then it could raise global mean sea level by several metres.</p>
<p>There have been periods of rapid global sea-level rise <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011RG000371">in the past</a> (by 1cm–2cm per year). This probably happened because glaciers were losing mass at an accelerated rate. One of the key mechanisms responsible for this is known as “<a href="https://www.antarcticglaciers.org/antarctica-2/west-antarctic-ice-sheet-2/marine-ice-sheets/">marine ice sheet instability</a>”. </p>
<p>When glaciers, like those in west Antarctica, experience a small retreat due to some change in the climate, they can continue retreating even if the change is reversed. Essentially, the glacier gets pushed beyond a tipping point, whereby it experiences rapid mass loss until it reaches a new state.</p>
<p>This kind of retreat is irreversible because the change in climate needed for the glacier to recover its original position is much greater than what initially caused it to retreat. This instability mechanism is well understood in theory, and models show it could happen in west Antarctica in the future. But until now there has been no proof that it had happened in the past.</p>
<p>In a <a href="https://www.nature.com/articles/s41558-023-01887-y">new study</a>, we found that Pine Island Glacier experienced irreversible mass loss and retreat, starting in the 1940s. Our model suggests that a temporary increase in melting under its floating ice shelf was enough to push the glacier past a tipping point.</p>
<p>This phase of accelerated retreat had finished by the 1990s. But, in a <a href="https://tc.copernicus.org/articles/15/1501/2021/">separate study</a> where we used the same model, we found that the glacier will cross future tipping points unless global warming is kept within safe limits.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/565188/original/file-20231212-29-11ree3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A glacier flowing into the ocean in west Antarctica." src="https://images.theconversation.com/files/565188/original/file-20231212-29-11ree3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565188/original/file-20231212-29-11ree3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565188/original/file-20231212-29-11ree3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565188/original/file-20231212-29-11ree3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565188/original/file-20231212-29-11ree3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565188/original/file-20231212-29-11ree3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565188/original/file-20231212-29-11ree3.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">If it collapses, the west Antarctic ice sheet could raise global mean sea level by several metres.</span>
<span class="attribution"><span class="source">Hilmar Gudmundsson</span></span>
</figcaption>
</figure>
<h2>What happened?</h2>
<p>Before the 1940s, Pine Island Glacier extended further than it does today. Its grounding line – the point at which glacial ice begins to float in the ocean rather than being in contact with the ground – was situated 40km further downstream on a shallow ridge on the seabed. This ridge provided a stable position for the glacier, keeping it in place, possibly for at least 5,000 to 10,000 years.</p>
<p>Recent <a href="https://www.science.org/doi/full/10.1126/science.1244341">observations</a> show that ocean conditions beneath the floating ice shelf change from year to year. Every so often, warmer waters come into contact with the floating underside of the ice, causing a lot of melting from below. In the 1940s, a climate anomaly in west Antarctica, which has been <a href="https://www.pnas.org/doi/abs/10.1073/pnas.0803627105">linked to a large El Niño event</a>, possibly triggered a temporary change in ocean conditions. </p>
<p>We found that an increase in melting due to changed ocean conditions beneath the ice shelf would have led to the thinning of its grounded ice further upstream. This caused a gap to open between the grounded glacier and seabed, allowing warmer ocean waters to flow beyond the ridge. These results are supported by <a href="https://www.nature.com/articles/nature20136">evidence</a> recovered from the sediments under the present-day ice shelf.</p>
<p>Once warmer waters circulate beneath the newly exposed ice, it triggers further melting and thinning, at an even faster rate. Our model shows that this sparked rapid retreat and accelerated ice flow over the following two to three decades, culminating with the detachment of the ice shelf from the ridge between the late 1970s and the early 1980s. The pattern and timescale of retreat shown in our model is consistent with <a href="https://www.nature.com/articles/ngeo890">observations</a> of changes in the glacier.</p>
<h2>Irreversible change</h2>
<p>After the ice shelf detached from the ridge, there was a slowdown in ice flow and a more gradual retreat. This retreat only stopped when the grounding line reached a shallow section of bedrock in the early 1990s. </p>
<p>Our analysis shows that the phase of rapid retreat between the 1940s and 1970s was irreversible. If ocean conditions cooled and there was lower melting beneath the shelf during that period, then this would have been unable to stop the ongoing mass loss. </p>
<p>These results show us that if there is a significant increase in melting at the base of a glacier’s floating ice shelf, it can retreat past a tipping point. This means that even if conditions cool down, the loss of ice mass may be irreversible.</p>
<p>The future implications of this are clear. What occurred before could happen again. If we cross future ice sheet tipping points, simply reverting back to the previous climate conditions might not be enough to fix the damage.</p>
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<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">
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<hr><img src="https://counter.theconversation.com/content/219533/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brad Reed receives funding from The Natural Environment Research Council and UK Research and Innovation.</span></em></p><p class="fine-print"><em><span>Hilmar Gudmundsson receives funding from The Natural Environment Research Council, NSF and EU Horizon 2020 programme. </span></em></p><p class="fine-print"><em><span>Mattias Green receives funding from The Natural Environment Research Coucil. </span></em></p>Pine Island Glacier passed a tipping point decades ago, and it could do again in the future.Brad Reed, Research Fellow in the Department of Geography and Environmental Sciences, Northumbria University, NewcastleHilmar Gudmundsson, Professor of Glaciology, Northumbria University, NewcastleMattias Green, Professor in Physical Oceanography, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2181192023-11-28T17:59:20Z2023-11-28T17:59:20ZCOP28: Earth’s frozen zones are in trouble – we’re already seeing the consequences<p>As this year’s UN climate summit (<a href="https://www.cop28.com/">COP28</a>) gets under way in Dubai, scientists studying Earth’s frozen regions have been delivering an urgent call for action to policy makers. But is anyone listening? </p>
<p>Throughout 2023, we have been warning of an impending series of crises occurring in the cryosphere – polar ice sheets, ice shelves, sea ice, mountain glaciers and permafrost. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1724640545212084319"}"></div></p>
<p>The Scientific Committee on Antarctic Research (<a href="https://www.scar.org/">SCAR</a>) released its <a href="https://scar.org/library/scar-publications/occasional-publications/5758-acce-decadal-synopsis/">decadal synopsis</a> on the state of Antarctic climate change and ecosystems. It led the recent Antarctic Treaty meeting to issue the <a href="https://www.ats.aq/devAS/Meetings/Measure/806">Helsinki Declaration</a> to highlight that significant observed changes in Antarctica influence climate impacts globally.</p>
<p>The World Climate Research Programme (<a href="https://www.wcrp-climate.org/">WCRP</a>) has prepared the <a href="https://unitingtocombatntds.org/en/the-kigali-declaration/">Kigali Declaration</a>, summarising the latest climate science to highlight the urgency at COP28.</p>
<p>And this month, a <a href="https://www.iccinet.org/statecryo23/">State of the Cryosphere 2023</a> report assessing the most recent science warned that even 2°C of warming would trigger irreversible loss of ice sheets, glaciers, snow, sea ice and permafrost, with disastrous consequences for society and nature. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1728061951983390940"}"></div></p>
<p>I have contributed to all three documents. Some of the most dramatic changes are occurring in Antarctica and the Southern Ocean, including extreme heatwaves, record lows in sea ice and the emergence of an amplified warming pattern across the entire Antarctic continent. </p>
<p>These changes are melting Antarctica’s ice sheet and delivering vast quantities of freshwater to the ocean. This in turn drives an accelerating rise in shorelines around the world. </p>
<p>Polar warming is also contributing to drought and wildfires in Australia, floods in New Zealand and extreme weather at every latitude.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-can-still-prevent-the-collapse-of-the-west-antarctic-ice-sheet-if-we-act-fast-to-keep-future-warming-in-check-215878">We can still prevent the collapse of the West Antarctic ice sheet – if we act fast to keep future warming in check</a>
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</em>
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<hr>
<h2>Breaching planetary thresholds</h2>
<p>In July this year, average monthly global temperatures breached 1.5°C above pre-industrial levels for the first time. With a large El Niño event underway in the Pacific, 2023 is virtually certain to be the hottest year on record. </p>
<p>The World Meteorological Organisation predicts the world is on track to <a href="https://public.wmo.int/en/our-mandate/climate/wmo-statement-state-of-global-climate">exceed the Paris target</a> to keep warming below 2°C within the next five years, on an annual basis.</p>
<p>Scientific evidence is clear that due to the current trajectory of human-derived greenhouse gas emissions, the polar regions will continue to warm at rates of up to four times the global average. </p>
<p>This is because of self-reinforcing feedbacks, such as those related to retreating sea ice. The more sea ice melts, the more energy the darker ocean surface absorbs, in turn leading to more land ice melting and the potential crossing of tipping points linked to temperature thresholds close to 1.5-2°C of global warming. </p>
<figure class="align-center ">
<img alt="This map shows the location of climate elements in the cryosphere (blue), biosphere (green), and ocean/atmosphere (orange), and global warming levels at which their tipping points will likely be triggered." src="https://images.theconversation.com/files/560314/original/file-20231120-21-xolre7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560314/original/file-20231120-21-xolre7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=346&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560314/original/file-20231120-21-xolre7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=346&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560314/original/file-20231120-21-xolre7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=346&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560314/original/file-20231120-21-xolre7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560314/original/file-20231120-21-xolre7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560314/original/file-20231120-21-xolre7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Several of Earth’s potential tipping points are in the cryosphere.</span>
<span class="attribution"><a class="source" href="https://www.science.org/doi/10.1126/science.abn7950">Author supplied</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>There are two key planetary thresholds in the polar regions. Firstly, thawing permafrost in the Arctic has the potential for widespread release of methane and carbon dioxide into the atmosphere, further enhancing global heating. </p>
<p>Secondly, meltdown of up to two-thirds of Antarctica’s ice sheet may become irreversible, locking in multi-metre sea-level rise for generations to come even if the warming were to stop or reverse after peaking before 2100.</p>
<h2>Dramatic consequences at all latitudes</h2>
<p>The Southern Ocean has taken up most of the heat from global warming (70%). This excess energy will remain in the ocean for centuries and continue melting parts of the coastal fringes of Antarctica from underneath.</p>
<p>The amplified polar warming is accelerating the melting of ice sheets. They are now the <a href="https://www.ipcc.ch/ar6-syr/">largest contributors to rising global sea levels</a>. But they respond slowly, trapping heat and releasing it over long timescales. Sea-level rise will therefore continue for centuries to come, even with net zero emissions. </p>
<p>Projections show substantial differences between low- and high-emissions scenarios, especially after 2050. A high-emissions scenario could result in multi-metre sea-level rise for coming centuries. This includes a “low likelihood, high impact” scenario in which two metres by 2100 cannot be ruled out due to rapid loss of Antarctica’s fringing ice shelves and consequent melting of the ice sheet. </p>
<p>The ice shelves currently stabilise the interior ice sheet and protect it from erosion by encroaching warming ocean waters. <a href="https://www.ipcc.ch/report/ar6/syr/downloads/report/IPCC_AR6_SYR_SPM.pdf">Evidence suggests</a> the Paris climate target of limiting heating to 1.5-2C°C is a threshold for widespread ice shelf loss.</p>
<p>The loss of two-thirds of the world’s high mountain glaciers (often referred to as the third pole) is also likely. This will affect two billion people who depend on these frozen water stores for their drinking, power production, agriculture and related ecosystems services. </p>
<p>As glacial lakes fill up, more people will be exposed to hazards such as the recent <a href="https://www.bbc.com/news/world-asia-india-67050830">glacial outburst flood and landslides in Sikkim</a> in India’s northeast.</p>
<p>Intense high-latitude, low-pressure systems – “bomb cyclones” – are now bringing extreme temperatures and precipitation via <a href="https://tc.copernicus.org/articles/17/865/2023/">atmospheric rivers</a> to coastal regions and the interior of Antarctica and Greenland. These extremes cause unseasonal weather not only in polar regions, but also in lower latitudes, including New Zealand.</p>
<h2>Changing icescapes</h2>
<p>An unprecedented <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL104910">heat wave occurred over East Antarctica</a> in March 2022, peaking at 39°C above the climatological average. It was the largest temperature anomaly ever recorded globally. A local ice shelf, which was in a vulnerable state, collapsed within days.</p>
<p>This demonstrates the potential of future heatwaves over the warmer, lower-elevation West Antarctic Ice Sheet to trigger surface melting and <a href="https://www.nature.com/articles/s43247-022-00422-9">collapse of ice shelves</a>.</p>
<p>During this year’s southern hemisphere winter, Antarctica’s sea ice cover reached a 40-year low. This followed the <a href="https://spj.science.org/doi/10.34133/olar.0007">record low annual sea-ice minimum in early 2023</a>, due to an unseasonably warm Southern Ocean and changed atmospheric circulation patterns that brought warm air south.</p>
<figure class="align-center ">
<img alt="This graph shows anomalies in Antarctica’s sea-ice extent (in millions of square kilometres) for each year from 1978 to 2023." src="https://images.theconversation.com/files/560539/original/file-20231120-21-uknzp8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560539/original/file-20231120-21-uknzp8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560539/original/file-20231120-21-uknzp8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560539/original/file-20231120-21-uknzp8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560539/original/file-20231120-21-uknzp8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=402&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560539/original/file-20231120-21-uknzp8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=402&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560539/original/file-20231120-21-uknzp8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=402&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">During 2023, the extent of Antarctica’s sea ice reached a record low.</span>
<span class="attribution"><span class="source">National Snow and Ice Data Centre</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>These unprecedented changes were well outside the range of natural variability. They coincide with new evidence from a <a href="https://www.nature.com/articles/s41558-023-01791-5">study of ice cores</a> that shows the emergence of an amplified surface-warming pattern over Antarctica. </p>
<h2>Decision makers still hold the power</h2>
<p>The <a href="https://www.ipcc.ch/report/sixth-assessment-report-cycle/">latest report</a> by the Intergovernmental Panel on Climate Change (<a href="https://www.ipcc.ch/">IPCC</a>) reinforces that “limiting warming well below 2°C involves rapid, deep and in most cases immediate greenhouse gas emissions reductions”. </p>
<p>However, it is now clearer than ever that policy is not responding at the pace and scale required to avert the impending nexus of global climate, ecological and environmental catastrophes. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/antarcticas-heart-of-ice-has-skipped-a-beat-time-to-take-our-medicine-202729">Antarctica's heart of ice has skipped a beat. Time to take our medicine</a>
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<p>Every nation’s emissions policy settings are <a href="https://climateactiontracker.org/climate-target-update-tracker-2022/">insufficient to achieve the Paris target</a>. New Zealand’s climate policies are assessed as “<a href="https://climateactiontracker.org/countries/new-zealand/">highly insufficient</a>”, but the country is not alone. The global policy response remains grossly ineffective and has been that way since the IPCC’s first report in 1990.</p>
<p>But the report provides some hope through “multiple feasible and effective, sustainable and equitable options to reduce greenhouse gas emissions and adapt to human caused climate change”. </p>
<p>Scientists made this clear in a <a href="https://council.science/publications/policy-brief-global-sea-level-rise/">policy briefing on sea-level rise</a> to the UN General Assembly, stating:</p>
<blockquote>
<p>Ambitious mitigation in line with the Paris Agreement is critical to avoiding thresholds that would yield rapid and irreversible sea-level rise and to enabling successful adaptation.</p>
</blockquote><img src="https://counter.theconversation.com/content/218119/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy Naish 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 world is on track to exceed 2°C warming within the next five years, with dire consequences for polar ice, mountain glaciers and permafrost – and human society.Timothy Naish, Professor in Earth Sciences, Te Herenga Waka — Victoria University of WellingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2184082023-11-27T17:01:47Z2023-11-27T17:01:47ZA Peruvian farmer is trying to hold energy giant RWE responsible for climate change – the inside story of his groundbreaking court case<p>On a crisp, sunny day high in the Peruvian Andes, two German judges gaze across a mountain lake to the towering white glaciers in the distance. Dark spots are visible on the pristine ice and, in quiet moments, the cold wind carries the sounds of creaking and cracking.</p>
<p>The judges, from the German city of Hamm, have flown more than 6,500 miles to witness the melting glaciers for themselves. It is May 2022 and their visit has taken more than three years to organise – and some intensive diplomatic negotiations between Peru and Germany. Also here, more than 4,500 metres above sea level, are five German and Austrian scientific experts flying drones to assess whether Lake Palcacocha poses a significant risk of flooding to the thousands of people in the valley below.</p>
<p>A throng of local Peruvian officials have tagged along too, to share their concerns about <a href="https://glacierlab.uoregon.edu/glacier-hazards-and-disasters/">glacier hazards</a> with the judges. Around two-dozen international journalists and four documentary film teams are in the area to <a href="https://www.washingtonpost.com/climate-environment/interactive/2022/peru-climate-lawsuit-melting-glacier/">cover the event</a>. But the judges have requested they stay away from the lake so the court can do its work.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/561132/original/file-20231122-15-2fn2tp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A high-altitude blue lake surrounded by snow-capped mountains." src="https://images.theconversation.com/files/561132/original/file-20231122-15-2fn2tp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/561132/original/file-20231122-15-2fn2tp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561132/original/file-20231122-15-2fn2tp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561132/original/file-20231122-15-2fn2tp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561132/original/file-20231122-15-2fn2tp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561132/original/file-20231122-15-2fn2tp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561132/original/file-20231122-15-2fn2tp.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>
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<span class="caption">Lake Palcacocha is fed by the region’s accelerating glacial melt.</span>
<span class="attribution"><a class="source" href="https://www.germanwatch.org/de/medienservice">Alexander Luna/Germanwatch</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>The deep-blue water glistens ominously in the sunshine. The lake is fed by the region’s accelerating <a href="https://www.ipcc.ch/srocc/chapter/chapter-2/">glacial melt</a>, powered by warming temperatures that were long ago shown to be the <a href="https://par.nsf.gov/servlets/purl/10299146">result of human climate emissions</a>.</p>
<p>Lake Palcacocha is the subject of an <a href="https://climatecasechart.com/non-us-case/lliuya-v-rwe-ag/">unprecedented climate justice lawsuit</a>. On one side, a German energy giant that is said to be responsible for 0.47% of the world’s industrial greenhouse gas emissions. On the other, a Quechua-speaking farmer who had never travelled outside Peru until he joined this <a href="https://climatecase.org/en">groundbreaking legal challenge</a>.</p>
<h2>The unlikely plaintiff</h2>
<p>The Cordillera Blanca mountain range in the northern Peruvian Andes is a region shaped by disaster. In 1941, Lake Palcacocha’s banks broke, probably due to an avalanche, devastating the city of Huaraz downstream and killing around 2,000 people.</p>
<p>The region’s most devastating disaster occurred three decades later in 1970, when an earthquake caused another massive avalanche that <a href="https://en.wikipedia.org/wiki/1970_Huascar%C3%A1n_debris_avalanche">destroyed the town of Yungay</a> and nearby villages, burying 30,000 people (although many of the town’s children survived because they were attending a nearby circus show). The disaster left a deep impact on the area’s social and cultural fabric. Yungay was permanently relocated and authorities stepped up their efforts to monitor glacial hazards.</p>
<p>As well as being a farmer, Saúl Luciano Lliuya works here as a mountain guide, leading tourists up the icy peaks year after year. Now in his early 40s, he came of age at a time of unprecedented environmental change in his homeland. Avalanches and glacial floods <a href="https://www.preventionweb.net/news/peru-dangers-glacial-lake-floods-pioneering-and-capitulation#:%7E:text=Climate%20change%20is%20creating%20new,Cordillera%20Blanca%20to%20expand%20rapidly.">happen more and more often</a>, and he has lost a number of colleagues and friends. <a href="https://hess.copernicus.org/articles/20/2519/2016/">Flood modelling studies</a> show that Luciano Lliuya’s family home is in the danger zone if another large avalanche was to fall into Lake Palcacocha, causing its banks to burst.</p>
<p>As in many parts of the world, climate change has intensified existing vulnerabilities in the rural Andes while creating new dimensions of risk. Luciano Lliuya comes from an Indigenous population subjugated by Spanish colonisers that still faces marginalisation today. He grew up speaking Quechua at home and faced discrimination at school in Huaraz. Teachers only used Spanish and beat children for speaking their Indigenous language.</p>
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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>
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<p>In recent decades, an upsurge in mountain climbing tourism has created new opportunities for villagers such as Luciano Lliuya, who have traversed high altitudes since an early age. To them, mountains are more than just boulders and ice. “A mountain is a geological formation,” he says, “but another perspective is that the mountains nurture us. They are powerful beings of some sort … For me, the mountain is someone who gives you everything.”</p>
<p>Many of the local people make tribute payments to these mountains, hoping to avoid their wrath and guarantee plentiful harvests. Up at Lake Palcacocha, the villagers who oversee an early-warning flooding system installed by the Ancash region’s government also present ritual offerings to the mountains every month. They say that when they missed one in 2017, an avalanche crashed into the lake causing waves of several metres – but that time, the old safety dams held steady.</p>
<p>Luciano Lliuya too feels a deep responsibility for the mountains that are suffering as they <a href="https://www.mdpi.com/2071-1050/15/9/7610">lose their white covers</a>. Before summiting a peak on a climbing tour, he pays respect by laying coca leaves on the glacial ice. If he fails to show respect, he fears the mountain will show its anger.</p>
<p>Almost ten years ago, Luciano Lliuya was introduced via his father to a group of climate activists from the environmental NGO <a href="https://www.germanwatch.org/en/about">Germanwatch</a>. They discussed the chance to ask one of the world’s biggest greenhouse gas emitters, German energy giant RWE, to make a tribute payment to these mountains too.</p>
<p>If the case succeeds, it could set a global precedent to hold major polluters responsible for the effects of climate change, even on the other side of the world. Already, it has had a significant impact. After the case was <a href="https://www.theguardian.com/environment/2017/nov/30/german-court-to-hear-peruvian-farmers-climate-case-against-rwe">declared admissible by the German judges</a> in November 2017 – meaning that Luciano Lliuya had won a key legal argument, if not yet the scientific ones – RWE’s stock value <a href="https://www.lse.ac.uk/granthaminstitute/wp-content/uploads/2023/05/working-paper-397_-Sato-Gostlow-Higham-Setzer-Venmans.pdf">took a hit</a>. This reflects a broader trend: international companies and their investors are waking up to the <a href="https://greencentralbanking.com/research/impacts-of-climate-litigation-on-firm-value/">financial risks posed by climate litigation</a>.</p>
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<h2>Taking on a German energy giant</h2>
<p>Meeting Luciano Lliuya in his tiny village of Llupa, you’d hardly think he’d become something of a climate justice celebrity. The case has taken him to German courts and international UN summits. Having once been nervous about speaking at his local village assemblies, he has now addressed thousands of people at major climate marches and given countless interviews to the world’s press.</p>
<p>At home, his quiet life is periodically disturbed by <a href="https://www.youtube.com/watch?v=oAcJile4Idk">visiting film teams</a>. He says he doesn’t care much for stardom, but appreciates the interest in his legal case:</p>
<blockquote>
<p>I want people to know what we’re facing here in Peru. The people in wealthy countries like Germany should understand how climate change is making our lives more dangerous. Perhaps that will motivate them to stop polluting so much.</p>
</blockquote>
<p>I first visited his two-storey family home in December 2014, when I was asked to interpret for three representatives from Germanwatch (I’ve since worked with Luciano Lliuya as a legal strategist, scientific adviser and academic researcher). We were treated to a special meal of guinea pig and potatoes with red chilli sauce. Half-way through, he smiled and glanced around the table at his fellow diners including his father, Julio. Then he told us all quietly: “I’ll do it. I’ll do the claim.”</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/561128/original/file-20231122-29-c8epap.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Peruvian man standing amid mountains." src="https://images.theconversation.com/files/561128/original/file-20231122-29-c8epap.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/561128/original/file-20231122-29-c8epap.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561128/original/file-20231122-29-c8epap.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561128/original/file-20231122-29-c8epap.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561128/original/file-20231122-29-c8epap.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561128/original/file-20231122-29-c8epap.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561128/original/file-20231122-29-c8epap.jpeg?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"></a>
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<span class="caption">Saúl Luciano Lliuya in his mountain home.</span>
<span class="attribution"><a class="source" href="https://www.germanwatch.org/de/medienservice">Alexander Luna/Germanwatch</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<p>That moment marked a transformation of Luciano Lliuya’s life – and mine. In the run-up to the <a href="https://en.wikipedia.org/wiki/2014_United_Nations_Climate_Change_Conference">2014 UN Climate Summit</a> (COP20) in Peru’s capital, Lima, Germanwatch employees had been taking an interest in the Cordillera Blanca mountain range – a region of particular concern for its vulnerability to climate change. Having recently lived in Peru, I joined the team as they looked for local people in the Andes to help voice this concern.</p>
<p>A Peruvian friend who was working with local farmers in the region suggested Julio Luciano Lliuya, who had recently told him how badly climate change was affecting their community’s livelihood. Following two weeks of intense UN negotiations at the COP20 summit, I embarked on an eight-hour bus ride to Huaraz with three Germanwatch representatives.</p>
<p>Father and son met us in the city with their rickety old Toyota van. Navigating uneven dirt-track roads, they took us on a tour of the mountains and told us about their climate-related concerns: in the short term, glacial retreat causing disastrous avalanches and floods; in the longer term, water scarcity threatening their very way of being.</p>
<p>Keen to show us the glaciers up close, Julio’s only son Saúl took us on a six-hour trek up to Lake Palcacocha. The hike was so strenuous that two of my colleagues had to turn around halfway, struggling with altitude sickness. Whatever breath I had left was taken away when I first glimpsed the lake, with those shiny white glaciers framing its deep blue water.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/561156/original/file-20231122-19-goicyt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A mountain lake and the glaciers that feed it." src="https://images.theconversation.com/files/561156/original/file-20231122-19-goicyt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/561156/original/file-20231122-19-goicyt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561156/original/file-20231122-19-goicyt.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561156/original/file-20231122-19-goicyt.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561156/original/file-20231122-19-goicyt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561156/original/file-20231122-19-goicyt.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561156/original/file-20231122-19-goicyt.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>
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<span class="caption">Lake Palcacocha has previously flooded the valley below with catastrophic results.</span>
<span class="attribution"><a class="source" href="https://www.germanwatch.org/de/medienservice">Germanwatch</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<p>Walking along the lake’s edge, a distant crash broke the silence. “It’s just a small avalanche – that happens all the time,” explained one of the villagers working for the local government who are present here around the clock to watch over the lake. Far away on the glacier, I spotted a flurry of falling snow. “You see? This one didn’t even reach the lake.” I wondered about the consequences of a bigger avalanche on the residents of the valley below, including the Luciano Lliuya family.</p>
<p>Back down in the village over our guinea pig lunch, Julio (who was in his seventies) explained he had transferred his property in the flood danger zone to his seven children. To our surprise, the youngest of them, Saúl, offered to make the claim against RWE.</p>
<p>“All right then,” said Christoph Bals, Germanwatch’s policy director. “We’re going to court!”</p>
<h2>An outlandish idea</h2>
<p>When I began working on this project nearly a decade ago, holding a major emitter responsible for climate change occurring across the world seemed an outlandish idea. <a href="https://dialnet.unirioja.es/servlet/articulo?codigo=3351365">German lawyers</a> had come up with the idea of bringing a claim under the country’s <a href="https://jur-law.de/en/2022/04/neighborhood-right-federation-state-berlin-2/">neighbourhood law</a> (part of the extensive <a href="https://www.gesetze-im-internet.de/englisch_bgb/englisch_bgb.html#p3704">German Civil Code</a>) – but this idea had yet to be tested in court.</p>
<p>When Saúl Luciano Lliuya first heard about this option, he said his preferred option was to confront a major polluter, so we settled on a claim against the <a href="https://en.wikipedia.org/wiki/RWE">German multinational RWE</a>. Based some 6,500 miles away in the industrial city of Essen, RWE has produced coal-fired energy since it was founded in the 19th century. Much more recently, its plans for the huge new Garzweiler open-cast coalmine in western Germany have been met with <a href="https://www.theguardian.com/artanddesign/2023/jan/24/eviction-lutzerath-village-destroyed-coalmine-a-photo-essay">sustained protests</a> and some controversy about <a href="https://theconversation.com/german-police-have-long-collaborated-with-energy-giant-rwe-to-enforce-ecological-catastrophe-198095">RWE’s relationship with the regional police</a>.</p>
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Read more:
<a href="https://theconversation.com/german-police-have-long-collaborated-with-energy-giant-rwe-to-enforce-ecological-catastrophe-198095">German police have long collaborated with energy giant RWE to enforce ecological catastrophe</a>
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<p>Over the past 25 years, the energy company has diversified into renewable energy, and states that it will be “<a href="https://www.rwe.com/en/responsibility-and-sustainability/environmental-protection/climate-protection/#:%7E:text=RWE%20will%20be%20climate%20neutral,with%20the%20Paris%20Climate%20Agreement.">climate neutral by 2040</a>”. A <a href="https://climateaccountability.org/pdf/MRR%209.1%20Apr14R.pdf">2014 study</a>, commissioned by the <a href="https://climatejustice.org.au/about-us">Climate Justice Programme</a> in Australia, estimated that RWE had produced 0.47% of all the world’s industrial greenhouse gas emissions between 1854 and 2010. </p>
<p>In Luciano Lliuya’s homeland, the local government plans to build a new dam and drainage system at Lake Palcacocha to reduce the risk of flooding, at a projected cost of about US$4 million. Luciano Lliuya, via the lawsuit, wants RWE to cover 0.47% of that sum, or around US$20,000.</p>
<p>The case’s central argument is simple: that climate change makes <a href="https://journals.sagepub.com/doi/full/10.1177/14634996221138338">everyone in the world potential neighbours</a> – so, RWE should be a good neighbour and accept its responsibility for contributing to climate change impacts in Peru.</p>
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<a href="https://images.theconversation.com/files/561149/original/file-20231122-25-nqchrr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Judges and photographers in a German courtroom" src="https://images.theconversation.com/files/561149/original/file-20231122-25-nqchrr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/561149/original/file-20231122-25-nqchrr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561149/original/file-20231122-25-nqchrr.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561149/original/file-20231122-25-nqchrr.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561149/original/file-20231122-25-nqchrr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561149/original/file-20231122-25-nqchrr.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561149/original/file-20231122-25-nqchrr.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>
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<span class="caption">Judges hear the climate lawsuit against RWE in Hamm’s higher regional court, November 2017.</span>
<span class="attribution"><a class="source" href="https://www.germanwatch.org/de/medienservice">Alexander Luna/Germanwatch</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<p>Initially, a lower court in Essen <a href="https://www.germanwatch.org/en/13887">ruled</a> (in December 2016) that the lawsuit against the energy giant was <a href="https://rwe.climatecase.org/en/material/district-court-essen-decision">unfounded</a>. However, the following November, this was <a href="https://rwe.climatecase.org/en/material/higher-regional-court-hamm-indicative-court-order-and-order-hearing-evidence">overruled</a> by the Higher Regional Court in Hamm, which declared the case admissible and began examining the evidence.</p>
<p>The requested sum of US$20,000 is a symbolic amount of money, of course – RWE’s legal costs are likely to go much higher. Yet, when the judges suggested an out-of-court settlement at a hearing in 2017, the company’s lawyer refused, stating: “This is a matter of precedent.”</p>
<p>The estimated cost of future climate-related claims extends <a href="https://www.ft.com/content/055ef9f4-5fb7-4746-bebd-7bfa00b20c82">into the billions</a>.</p>
<h2>The legal strategy</h2>
<p>“This feels like we’re at 5,000 metres in the Andes,” remarks Saúl Luciano Lliuya as, fighting a biting wind, we walk to the Essen courthouse. It is November 2015 and this is his first trip outside Peru – accompanied by his father. Acting as guide and interpreter, I freeze alongside them in my thick winter coat while these two hardy Peruvians sport only light jackets.</p>
<p>A TV crew is filming as Luciano Lliuya enters the courthouse with his lawyer to submit the claim against RWE. They emerge a few minutes later, and he gives a statement to the awaiting journalists and TV cameras:</p>
<blockquote>
<p>I’m making this claim because the mountains in Peru are suffering. The glaciers are melting. We haven’t caused this problem – it’s big companies like RWE. Now they must take responsibility.</p>
</blockquote>
<p>Speaking to the press is a new and nerve-wracking experience for him. But when he thinks about the mountains and why he is taking this action, a fire seems to light up inside.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/561146/original/file-20231122-25-uj4iya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two Peruvian men outside a courthouse, one holding a large envelope." src="https://images.theconversation.com/files/561146/original/file-20231122-25-uj4iya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/561146/original/file-20231122-25-uj4iya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561146/original/file-20231122-25-uj4iya.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561146/original/file-20231122-25-uj4iya.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561146/original/file-20231122-25-uj4iya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561146/original/file-20231122-25-uj4iya.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561146/original/file-20231122-25-uj4iya.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>
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<span class="caption">Saúl Luciano Lliuya and his father Julio file the lawsuit at Essen courthouse, November 2015.</span>
<span class="attribution"><a class="source" href="https://www.germanwatch.org/de/medienservice">Hubert Perschke/Germanwatch</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<p>Later that day, after we escape the cameras, I ask what his neighbours back in Peru think about the lawsuit. His only aim, after all, is to benefit his community in the face of dramatic changes to their Andean environment. He seeks no personal gain; only that RWE covers part of the costs of a public infrastructure project to reduce the risk of flooding from Lake Palcacocha.</p>
<p>“I don’t know what [my fellow villagers] think,” Luciano Lliuya replies. “I haven’t told anyone.” Acknowledging my surprise, he says he isn’t sure how to explain it to them:</p>
<blockquote>
<p>They live with climate change in their own way, but they don’t all have the scientific facts. I’m afraid that some people might not understand how me going to Germany helps us in Peru.</p>
</blockquote>
<p>It turns out that his fear is well-founded. When his neighbours find out about his legal claim – whether from news reports, social media or word of mouth – some are confused by it. Rumours begin to spread: that he is making lots of money from the claim, or selling the lake to the Germans. Upon his return home, he explains to his neighbours that nobody is paying him to make the claim, and that success would ultimately help them all. Still, many remain suspicious.</p>
<p>The irony that this case, revolving around <a href="https://www.everestate.com/blog/neighbourhood-law">neighbourhood law</a>, risks upsetting his own neighbours in Peru is not lost on Luciano Lliuya. The lawsuit applies <a href="https://southerncalifornialawreview.com/2019/05/01/from-nuisance-to-environmental-protection-in-continental-europe-article-by-vanessa-casado-perez-carlos-gomez-liguerre/">nuisance law</a>, which is typically applied in neighbourhood disputes, to climate change impacts.</p>
<p>Imagine this: your neighbour has a wall that borders on your property. The wall is old and crumbling, and you’re afraid it could fall over and damage your house. If that happens, you can sue your neighbour for damages. But you’d rather not wait – you don’t want to live with the uncertainty. So instead, you sue your neighbour using the nuisance law. If you win, the court will order them to fix the wall – or in Luciano Lliuya’s case, get rid of the flood hazard.</p>
<p>Around the world, others have attempted similar lawsuits before, to no avail. In 2008, for example, the Native Alaskan community of Kivalina <a href="https://climatecasechart.com/case/native-village-of-kivalina-v-exxonmobil-corp/">filed a claim</a> against ExxonMobil and other oil majors in the US. Their village is threatened by rising sea levels, so the complainants demanded support for adaptation costs – but that case was dismissed on the grounds that climate change is a political issue that should not be resolved in the courts.</p>
<p>Since then, political progress has proved largely inadequate in mobilising support for those who are most vulnerable to climate change. At the same time, <a href="https://www.nature.com/articles/s41558-021-01086-7">climate science has evolved rapidly</a>, drawing ever more precise links between major emitters and impacts around the world.</p>
<p>Since 2017, around 40 US states and cities have <a href="https://theconversation.com/more-than-two-dozen-cities-and-states-are-suing-big-oil-over-climate-change-they-just-got-a-boost-from-the-us-supreme-court-205009">filed lawsuits</a> against the fossil fuel industry, arguing that companies such as ExxonMobil <a href="https://theconversation.com/exxon-scientists-accurately-forecast-climate-change-back-in-the-1970s-what-if-we-had-listened-to-them-and-acted-then-197944">knew about the dangers of climate change decades ago</a> but hid this knowledge from consumers. The plaintiffs have included cities such as New York and San Francisco that are threatened by sea level rise and have demanded billions of dollars to cover their adaptation costs. Their actions have received support from US president Joe Biden’s administration, and earlier in 2023, <a href="https://www.theguardian.com/environment/2023/apr/25/experts-hail-decision-us-climate-lawsuits-advance">the Supreme Court ruled</a> the cases should be heard in state rather than federal courts. Many legal analysts believe these cases have a better chance of success in state courts, and they are likely to go to trial soon.</p>
<p>After Dutch NGO <a href="https://en.milieudefensie.nl/about-us">Milieudefensie</a> filed a lawsuit against the oil and gas multinational Shell, in 2021 a <a href="https://www.theguardian.com/business/2021/may/26/court-orders-royal-dutch-shell-to-cut-carbon-emissions-by-45-by-2030">Dutch court ordered</a> that the company should reduce its emissions by 45% by 2030. (There are, though, enforcement challenges with multinational corporations, and since the verdict Shell has moved its corporate headquarters from the Netherlands to the UK.) Lawsuits in numerous countries have forced governments to increase climate action. But, almost eight years after he delivered the complaint to the snowy Essen courthouse in November 2015, Luciano Lliuya’s case has made it furthest of all.</p>
<p>Most fossil fuel companies are no longer engaging in <a href="https://www.theguardian.com/environment/ng-interactive/2019/oct/09/half-century-dither-denial-climate-crisis-timeline">climate denial</a>. RWE acknowledges the dangers of global warming and claims to be <a href="https://www.rwe.com/-/media/RWE/documents/09-verantwortung-nachhaltigkeit/cr-berichte/sustainability-strategy-report-2022.pdf">“at the leading edge of the shift to sustainable energy.”</a> Yet the company is still making massive profits with fossil fuels, and refuses to pay up for damage caused by past emissions.</p>
<h2>A battle over the science</h2>
<blockquote>
<p>I know of no other case where attribution science is so important. This is a real battle of science. (Roda Verheyen, Luciano Lliuya’s lead lawyer)</p>
</blockquote>
<p>In early 2021, Luciano Lliuya’s legal team submitted a new piece of impartial evidence: a <a href="https://www.nature.com/articles/s41561-021-00686-4">scientific study</a> linking flood risk in the Peruvian Andes to global warming. It found that around 95% of the glacier’s retreat at Lake Palcacocha is <a href="https://www.theguardian.com/environment/2021/feb/04/global-heating-to-blame-for-threat-of-deadly-flood-in-peru-study-says">due to human-made climate change</a>. One media article called it a “<a href="https://insideclimatenews.org/news/04022021/for-a-city-staring-down-the-barrel-of-a-climate-driven-flood-a-new-study-could-be-the-smoking-gun/">smoking gun</a>”.</p>
<p>After RWE’s lawyers challenged the legal validity of the study, in July 2021 the court <a href="https://climatecase.org/en/material/higher-regional-court-hamm-order-and-reference-order">acknowledged it</a> as a piece of independently produced evidence, meaning it is “of higher value than private expert opinions commissioned by the parties”.</p>
<p>In response, RWE’s legal team presented a <a href="https://www.mdpi.com/2072-4292/13/14/2694">study in the scientific journal Remote Sensing</a>, which analysed satellite data for the glacier above Lake Palcacocha and found there was “no evidence of significant glacial instability” within a three-year observation period. RWE’s lawyers used this study to argue that a large avalanche is unlikely – a position that has been strongly contested by Luciano Lliuya’s legal team.</p>
<p>RWE states that as well as modernising its coal-fired power plants to reduce CO₂ emissions, it has invested billions in renewable energy, reflecting <a href="https://www.bundesregierung.de/breg-en/issues/climate-action/government-climate-policy-1779414">Germany’s policy to phase out fossil fuels</a>. Within an article about the case on the <a href="https://www.source-material.org/battle-of-science-rages-over-peru-glacier/">climate investigations website SourceMaterial</a>, RWE spokesperson Guido Steffen commented:</p>
<blockquote>
<p>Individual emitters are not liable for universally rooted and globally effective processes like climate change. It is judicially impossible to relate specific or individual consequences of climate change to a single person.</p>
</blockquote>
<h2>‘This close to winning’</h2>
<p>In the years since I first met Luciano Lliuya in 2014, as well as working with him as a legal adviser and strategist, I’ve also <a href="https://www.escholar.manchester.ac.uk/uk-ac-man-scw:327995">completed a PhD</a> on how climate change affects people in the Peruvian Andes, linking their concerns with legal and political discussions across the world. But the case is still far from over: legal proceedings move slowly, and the next hearing is due to be held in the first half of 2024.</p>
<p>But the case has already inspired other claims: in July 2022, Indonesian islanders threatened by sea-level rise filed a <a href="https://www.theguardian.com/world/2022/jul/20/indonesian-islanders-sue-cement-holcim-climate-damages">similar lawsuit</a> against the Swiss cement producer Holcim. A <a href="https://climatecasechart.com/non-us-case/greenpeace-italy-et-al-v-eni-spa-the-italian-ministry-of-economy-and-finance-and-cassa-depositi-e-prestiti-spa/">recent case</a> in Italy asks for a declaration of responsibility for climate damage from ENI, an Italian oil company. And in September 2023, the <a href="https://theconversation.com/portuguese-youths-sue-33-european-governments-at-eu-court-in-largest-climate-case-ever-214092">European Court of Human Rights heard a legal action</a> posed by Portuguese young people aged 11-24 against 33 European governments over what they claim is a failure to adequately tackle global heating.</p>
<p>Meanwhile, the plight of Luciano Lliuya’s community has been covered by <a href="https://rwe.climatecase.org/en/press-review">media outlets across the planet</a>. When his lawsuit began, it felt to all involved that victory was nearly impossible – we might get past a few legal hurdles, then move on to the next case. Almost a decade on, we never imagined we’d get this far, and be this close to winning the case.</p>
<p>Back in Luciano Lliuya’s village, the criticism of his motives has slowly subsided. “A big step was when the court came to visit us [in 2022],” Luciano Lliuya explains. “People saw that this is something serious. It wasn’t just me.”</p>
<p>Community leaders joined the court’s inspection at Lake Palcacocha and shook the judges’ hands. At the same time, Luciano Lliuya has helped establish a local NGO that supports farmers in adapting to climate change through sustainable agriculture. The organisation is called <a href="https://www.wayintsikperu.org/en">Wayintsik</a> – Quechua for “our house”.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/561158/original/file-20231122-29-l0o584.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Peruvian man with grassy mountains behind." src="https://images.theconversation.com/files/561158/original/file-20231122-29-l0o584.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/561158/original/file-20231122-29-l0o584.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561158/original/file-20231122-29-l0o584.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561158/original/file-20231122-29-l0o584.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561158/original/file-20231122-29-l0o584.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561158/original/file-20231122-29-l0o584.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561158/original/file-20231122-29-l0o584.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">Luciano Lliuya says he feels responsibility for the mountains that are suffering as they lose their white covers.</span>
<span class="attribution"><a class="source" href="https://www.germanwatch.org/de/medienservice">Germanwatch</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>While the legal process moves slowly on, they have no choice but to adapt – and not just to the threat posed by the lake. Weather patterns are becoming less reliable. The Peruvian Andes usually have a dry season from May to August, and farmers rely on the first rains in September to plant their crops. Now, the rains sometimes begin too early, or not until November. New pests are also harming their potato harvests – the warming climate has brought rats to higher altitudes, for example.</p>
<p>In the long term, climate change could have even more devastating impacts on Luciano Lliuya’s community. Glaciers are natural water storage devices so, as they disappear, the people here will face <a href="https://www.sciencedirect.com/science/article/pii/S2214581822000763">water scarcity</a>. “If there’s no more water,” he says, “we’ll lose our livelihoods. There will be nothing left.” No water for the fields, no glaciers to climb.</p>
<p>But Luciano Lliuya is stubborn. In the face of malicious rumours and unwanted attention, others might have given up. He just climbed more mountains.</p>
<p>After attending COP27 in Sharm El-Sheikh in November 2022, he went on an all-night trek which included climbing Mount Sinai, following in the steps of Moses. The sandy landscape was a sharp contrast to the glaciers and green pastures he is used to in Peru. Squinting into the rising sun, he reflected on the perils of life on a warming planet.</p>
<p>He said it made him imagine a bleak future in which the whole world resembles these surroundings: “That’s why I’ll continue fighting – so that our mountains back home don’t turn to desert too one day.”</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>
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</figcaption>
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<p class="fine-print"><em><span>Noah Walker-Crawford receives funding from the Economic and Social Research Council of the United Kingdom and the Foundation for International Law for the Environment. He is a member of the Board of Trustees at Stiftung Zukunftsfähigkeit (Foundation for Sustainability). He was previously employed by and has acted as a consultant for Germanwatch. </span></em></p>If this case succeeds, it could set a precedent to hold major polluters responsible for the effects of climate change – even on the other side of the world.Noah Walker-Crawford, Postdoctoral Research Fellow in Political Science, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2160302023-10-23T15:19:25Z2023-10-23T15:19:25ZIncreasing melting of West Antarctic ice shelves may be unavoidable – new research<figure><img src="https://images.theconversation.com/files/555284/original/file-20231023-21-tlq49h.jpg?ixlib=rb-1.1.0&rect=0%2C666%2C4592%2C2385&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/icebergs-antarctic-continent-165228470">Evgeny Kovalev SPB/Shutterstock</a></span></figcaption></figure><p>The rate at which the warming Southern Ocean melts the West Antarctic ice sheet will speed up rapidly over the course of this century, regardless of how much emissions fall in coming decades, <a href="https://www.nature.com/articles/s41558-023-01818-x">our new research</a> suggests. This ocean-driven melting is expected to increase sea-level rise, with consequences for coastal communities around the world.</p>
<p>The Antarctic ice sheet, the world’s largest volume of land-based ice, is a system of interconnected glaciers comprised of snowfall that remains year-round. Coastal ice shelves are the floating edges of this ice sheet which stabilise the glaciers behind them. The ocean melts these ice shelves from below, and if melting increases and an ice shelf thins, the speed at which these glaciers discharge fresh water into the ocean increases too and sea levels rise. </p>
<p>In West Antarctica, particularly the Amundsen Sea, this process has been underway for decades. Ice shelves are <a href="https://doi.org/10.1126/science.aaa0940">thinning</a>, glaciers are <a href="https://doi.org/10.1002/2013GL059069">flowing faster</a> towards the ocean and the ice sheet is <a href="https://doi.org/10.1038/s41586-018-0179-y">shrinking</a>. While ocean temperature measurements in this region are limited, modelling suggests it may have <a href="https://doi.org/10.1029/2021gl094566">warmed as a result of climate change</a>.</p>
<p>We chose to model the Amundsen Sea because it is the most vulnerable sector of the ice sheet. We used a regional ocean model to find out how ice-shelf melting will change here between now and 2100. How much melting can be prevented by reducing carbon emissions and slowing the rate of climate change – and how much is now unavoidable, no matter what we do?</p>
<h2>Rapid change is locked in</h2>
<p>We used the UK’s national supercomputer <a href="https://www.archer2.ac.uk/">ARCHER2</a> to run many different simulations of the 21st century, totalling over 4,000 years of ocean warming and ice-shelf melting in the Amundsen Sea.</p>
<p>We considered different trajectories for fossil fuel burning, from the best-case scenario where global warming is limited to 1.5°C in line with the Paris Agreement, to the worst, in which coal, oil and gas use is uncontrolled. We also considered the influence of natural variations in the climate, such as the timing of events such as El Niño.</p>
<p>The results are worrying. In all simulations there is a rapid increase over the course of this century in the rate of ocean warming and ice-shelf melting. Even the best-case scenario in which warming halts at 1.5°C, something that is <a href="https://www.scientificamerican.com/article/the-world-will-likely-miss-1-5-degrees-c-why-isnt-anyone-saying-so/">considered ambitious</a> by many experts, entails a threefold increase in the historical rate of warming and melting.</p>
<p>What’s more, there is little to no difference between the scenarios up to 2045. Ocean warming and ice-shelf melting in the 1.5°C scenario is statistically the same as in a mid-range scenario, which is closer to what existing pledges to reduce fossil fuel use over the coming decades would produce.</p>
<p>The worst-case scenario shows more melting than the others, but only from around mid-century onwards, and many experts think this amount of future fossil fuel burning is <a href="https://doi.org/10.1016/j.eneco.2017.04.015">unrealistic</a> anyway. </p>
<p>The results imply that we are now committed to rapid ocean warming in the Amundsen Sea until at least 2100, regardless of international policies on fossil fuels.</p>
<p>The increases in warming and melting are the result of ocean currents strengthening and driving more warm water from the deep ocean towards the shallower ice shelves along the coast. Other <a href="https://doi.org/10.1029/2021GL094566">studies</a> have suggested this process is behind the ice shelf thinning measured by satellites. </p>
<h2>How much will the sea level rise?</h2>
<p>Melting ice shelves are a major cause of sea-level rise, but not the whole story. We can’t put a number on how much sea levels will rise without also simulating the flow of Antarctic glaciers and the rate of snow accumulating on the ice sheet, which our model didn’t include. </p>
<p>But we have every reason to believe that increased ice-shelf melting in this region will cause the rate at which sea levels are rising to speed up. </p>
<p>The West Antarctic ice sheet is already contributing substantially to global sea-level rise and is losing about <a href="https://doi.org/10.5194/essd-15-1597-2023">80 billion tonnes of ice a year</a>. It contains enough ice to cause <a href="https://doi.org/10.1038/s41561-019-0510-8">up to 5 metres of sea-level rise</a>, but we don’t know how much of it will melt, and how quickly. Our colleagues around the world are <a href="https://doi.org/10.1038/s41586-021-03302-y">working hard to answer this question</a>.</p>
<h2>Courage and hope</h2>
<p>There are some consequences of climate change that can no longer be avoided, no matter how much fossil fuel use falls. Substantial melting of West Antarctica up to 2100 may now be one of them.</p>
<p>How do you tell a bad news story? The conventional wisdom is that you’re supposed to give people hope: to say that there’s a disaster behind one door, but we can avoid it if only we choose a different one. What do you do when your science tells you that all doors lead to the same disaster?</p>
<p><a href="https://onbeing.org/blog/kate-marvel-we-need-courage-not-hope-to-face-climate-change/">Kate Marvel</a>, an atmospheric scientist, said that when it comes to climate change, “we need courage, not hope … Courage is the resolve to do well without the assurance of a happy ending”. In this case, courage means shifting our attention to the longer term. </p>
<p>The future will not end in 2100, even if most people reading this will no longer be around. Our simulations of the 1.5°C scenario show ice-shelf melting starting to plateau by the end of the century, suggesting that further changes in the 22nd century and beyond may still be preventable. Reducing sea-level rise after 2100, or even slowing it down, could save many coastal cities. </p>
<p>Courage means accepting the need to adapt, protecting coastal communities where it’s possible to do so, and rebuilding or abandoning them where it’s not. By predicting future sea-level rise in advance, we’ll have time to plan for it – rather than wait until the ocean is on our doorstep.</p>
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<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">
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<p class="fine-print"><em><span>Kaitlin Naughten receives funding from UK Research and Innovation and the National Environment Research Council. She is a member of Prospect.</span></em></p><p class="fine-print"><em><span>Jan De Rydt receives funding from UK Research and Innovation and the EU Horizon Europe funding programme.</span></em></p><p class="fine-print"><em><span>Paul Holland receives funding from UK Research and Innovation, Natural Environment Research Council and EU Horizon Europe funding programmes. He is a member of the Labour Party and Prospect.</span></em></p>Humanity has lost control of West Antarctic ice-sheet melting.Kaitlin Naughten, Ocean-Ice Modeller, British Antarctic SurveyJan De Rydt, Associate Professor of Polar Glaciology and Oceanography, Northumbria University, NewcastlePaul Holland, Ocean and Ice Scientist, British Antarctic SurveyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2148292023-10-09T12:21:30Z2023-10-09T12:21:30ZGlacial lake outburst floods in Alaska and the Himalayas show evolving hazards in a warming world<figure><img src="https://images.theconversation.com/files/551567/original/file-20231002-28-kdp55d.jpg?ixlib=rb-1.1.0&rect=153%2C0%2C986%2C661&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Glacial lakes are common in the Himalayas, as this satellite view shows. Some are dammed by glaciers, other by moraines.</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Lakes_of_Bhutan#/media/File:Glacial_lakes,_Bhutan.jpg">NASA </a></span></figcaption></figure><p>In August 2023, residents of Juneau, Alaska, <a href="https://alaskapublic.org/2023/08/07/juneaus-worst-glacial-outburst-flood-destroys-homes-and-displaces-residents/">watched as the Mendenhall River</a> swelled to historic levels in a matter of hours. The rushing water <a href="https://water.weather.gov/ahps2/hydrograph.php?wfo=pajk&gage=mnda2">undercut the riverbank</a> and swallowed whole stands of trees and multiple buildings.</p>
<p>The source for the flood was not heavy rainfall – it was a small glacial <a href="https://www.arcgis.com/apps/Cascade/index.html?appid=ad88fd5ccd7848139315f42f49343bb5">lake located in a side valley</a> next to the Mendenhall Glacier. </p>
<p>Glacier-dammed lakes like this are <a href="https://briannarick.github.io/dataviz/AKmapNov152021.html">abundant in Alaska</a>. They form when a side valley loses its ice faster than the main valley, leaving an ice-free basin that can fill with water. These lakes may remain stable for years, but often they reach a tipping point, when high water pressure opens a channel underneath the glacier.</p>
<p>The rapid and catastrophic <a href="https://www.youtube.com/watch?v=3nfiH1IB_Tk">drainage of lake water</a> that follows is called a <a href="https://www.antarcticglaciers.org/glacier-processes/glacial-lakes/glacial-lake-outburst-floods/">glacial lake outburst flood</a>, or GLOF for short. The flood waters race downstream over hours or days and often hit unexpectedly.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/opoTgIj97SU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Suicide Basin, a glacier-dammed lake, has flooded the Mendenhall River before. Scientists with the Alaska Climate Adaptation Science Center examined the glacial lake after an earlier flood.</span></figcaption>
</figure>
<p>Glacial lake outburst floods have destroyed homes, <a href="https://www.youtube.com/watch?v=W9lNnnui9bc">infrastructure</a> and human life around the world. They have killed <a href="https://doi.org/10.1016/j.gloplacha.2016.07.001">hundreds of people</a> in Europe and thousands of people in both <a href="https://doi.org/10.1016/j.gloplacha.2004.10.007">South America</a> and central Asia. Globally, an <a href="https://www.nature.com/articles/s41467-023-36033-x">estimated 15 million people</a> live downstream from these lakes, with those in Asia’s high mountains at greatest risk.</p>
<p>Flooding from a glacial lake in the Himalayas on Oct. 5, 2023, <a href="https://economictimes.indiatimes.com/news/india/sikkim-flash-flood-death-toll-increases-to-54-including-8-army-soldiers/articleshow/104246586.cms?from=mdr">left dozens of people dead</a> in India as water swept away bridges, damaged a hydropower station and flooded small towns. Satellite images showed <a href="https://ndma.gov.in/sites/default/files/PDF/PR-Flash-Flood-Sikkim-South%20Lhonak.pdf">that the lake level dropped markedly</a> within hours.</p>
<p><a href="https://akcasc.org/directory/rick/">I study</a> Alaska’s glacial lakes and the hazards that glacier-dammed lakes in particular can create. Our latest research shows how these lakes are changing as global temperatures rise.</p>
<h2>When glaciers hold back lakes</h2>
<p>Some <a href="https://nsidc.org/learn/ask-scientist/what-are-glacial-lakes">glacial lakes</a> are dammed by <a href="https://www.antarcticglaciers.org/glacial-geology/glacial-landforms/glacial-depositional-landforms/moraine-types/">moraines</a> – mounds of rock and debris that are left behind as a glacier retreats. Too much pressure from extreme rainfall or an avalanche or landslide into the lake can burst these dams, triggering a devastating flood. Officials say that’s likely what happened when the Himalayas’ <a href="https://youtu.be/cvVrK046-qE?feature=shared">Lhonak Lake flooded towns</a> in India in October 2023.</p>
<p>Glacier-dammed lakes, like Suicide Basin off of Mendenhall Glacier, are instead dammed by the glacier itself. </p>
<p>These glacial lakes tend to repeatedly fill and drain due to a cyclic opening and closing of a drainage path under the ice. The fill-and-drain cycles can create hazards every couple of years or multiple times a year.</p>
<figure class="align-center ">
<img alt="Two photo shows the same scene 125 years apart. The glacier loss is evident, and the lake between Suicide Glacier and Mendenhall Glacier didn't exist in 1983" src="https://images.theconversation.com/files/552380/original/file-20231005-19-kutg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552380/original/file-20231005-19-kutg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=577&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552380/original/file-20231005-19-kutg2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=577&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552380/original/file-20231005-19-kutg2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=577&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552380/original/file-20231005-19-kutg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=724&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552380/original/file-20231005-19-kutg2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=724&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552380/original/file-20231005-19-kutg2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=724&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Photos from 1893 and 2018 show how much Suicide Glacier has retreated and the glacier-dammed lake it left behind.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/news-features/event-tracker/major-flood-outburst-mendenhall-glacier-alaska-not-possible-without">NOAA/Alaska Climate Adaptation Science Center</a></span>
</figcaption>
</figure>
<h2>How glacier lake hazards are changing in Alaska</h2>
<p><a href="https://doi.org/10.1038/s41467-023-41794-6">In a new study</a>, we identified 120 glacier-dammed lakes in Alaska, 106 of which have drained at least once since 1985.</p>
<p>These lakes have collectively drained 1,150 times over 35 years. That is an average of 33 events every year where a lake drains its contents, sending a pulse of water downstream and creating potentially hazardous conditions.</p>
<p>Many of these lakes are in remote locations and often go undetected, while others are much closer to communities, such as Suicide Basin, which is within 5 miles of the state capital and has frequently drained over the past decade.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/3nfiH1IB_Tk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Time-lapse video shows how a glacier-dammed lake at Mendenhall Glacier drained over two days in early August 2023.</span></figcaption>
</figure>
<p><iframe id="9UtHE" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/9UtHE/6/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Our study found that, as a whole, glacier-dammed lakes in Alaska have decreased in volume since 1985, while the frequency of outbursts remains unchanged. This suggests a regional decline in the potential hazards from glacier-dammed lakes because less stored water is available, a trend that has been <a href="https://doi.org/10.1038/s41586-022-05642-9">documented for glacier-dammed lakes worldwide</a>.</p>
<p>To better understand this trend, imagine a bathtub. The higher the sides of the tub, the more water it can hold. For a glacier-dammed lake, the glacier acts as a side of the bathtub. Warming air temperatures are causing glaciers to melt and thin, lowering the tub walls and therefore accommodating less water. That reduces the total volume of water available for a potential glacial lake outburst flood.</p>
<p>Smaller lakes, however, have had less significant change in area over time. As the August 2023 event clearly illustrated, even small lakes can have significant effects downstream. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bKVdDkfbHUo?wmode=transparent&start=4" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drone video shows some of the damage after a glacial lake drained into the Mendenhall River near Juneau, Alaska.</span></figcaption>
</figure>
<p>Alaskans witnessed a new record of destruction in Juneau from the flood. The water reached <a href="https://water.weather.gov/ahps2/hydrograph.php?wfo=pajk&gage=mnda2">nearly 15 feet</a> at the Mendenhall River gauge – 3 feet above its previous record.</p>
<p>In summer 2023 alone, Alaskans saw record or near-record flooding from multiple glacier-dammed lakes near populated areas or infrastructure, such as <a href="https://www.weather.gov/ajk/suicideBasin">Suicide Basin</a>, near Juneau; <a href="https://www.weather.gov/aprfc/gdlData?12">Skilak Glacier-Dammed Lake</a>, which affects the Kenai River; and <a href="https://pubs.usgs.gov/sir/2022/5099/sir20225099.pdf">Snow Lake</a>, which impacts the Snow River. These lakes have remained about the same volume but have produced some larger floods in recent years. </p>
<p>One possible explanation is that with a thinner and weaker ice dam, the water can drain much more quickly, though further research is needed to understand the mechanics. Regardless, it’s a reminder that these lakes and events are unpredictable.</p>
<h2>How will rising temperatures affect these lakes?</h2>
<p><a href="https://doi.org/10.1038/s41586-021-03436-z">Glacier loss in Alaska is accelerating</a> as temperatures rise. Due to the large volume of glaciers and the many intersecting valleys filled with ice in Alaska, there is a high probability that new lakes will develop as side valleys deglaciate, introducing new potential hazards.</p>
<p>Many of these lakes are likely to develop in remote locations, and their presence may only be noticed in satellite images that reveal changes over time.</p>
<p>Given the abundance of glacial lakes and their <a href="https://doi.org/10.1038/s41467-023-36033-x">potential threat to human lives</a>, early warning and monitoring systems are worryingly sparse. Efforts are underway, such as those in the <a href="https://www.icimod.org/floods-glofs-and-early-warning-systems/">Himalayas</a> and <a href="https://www.sagaz.org/">Chile</a>, but further research is needed to develop reliable, low-cost monitoring systems and to improve our understanding of these evolving hazards.</p><img src="https://counter.theconversation.com/content/214829/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brianna Rick received funding from The National Science Foundation. </span></em></p>Alaska has at least 120 glacier-dammed lakes, and almost all have drained at least once since 1985, a new study shows. Small ones have been producing larger floods in recent years.Brianna Rick, Postdoctoral Fellow, Alaska Climate Adaptation Science Center, University of Alaska AnchorageLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2143092023-10-02T15:01:31Z2023-10-02T15:01:31ZGlaciers can give us clues about when a volcano might erupt<figure><img src="https://images.theconversation.com/files/550281/original/file-20230926-23-2qa2o3.jpg?ixlib=rb-1.1.0&rect=0%2C588%2C4000%2C2396&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/skier-snowy-volcano-niseko-hokkaido-japan-2139353883">Mayumi.K.Photography/Shutterstock</a></span></figcaption></figure><p>Globally, there is about one volcano erupting <a href="https://volcanoes.usgs.gov/vsc/file_mngr/file-153/FAQs.pdf">each week</a>. Volcanic unrest kills an average of <a href="https://doi.org/10.1186/s13617-017-0067-4">500 people every year</a> and costs the global economy roughly US$7 billion (£5.7 billion). With <a href="https://www.sciencedirect.com/science/article/abs/pii/S1464286702000025#:%7E:text=Using%20recently%20compiled%20databases%20of,during%20the%20last%2010%2C000%20years.">one in 20 people</a> living somewhere at risk of volcanic activity, every effort that can be made to improve the monitoring of volcanoes is important. </p>
<p>This is especially true for volcanoes covered by glaciers – <a href="https://doi.org/10.1016/j.gloplacha.2020.103356">roughly 18%</a> of all volcanoes on Earth. When these erupt, the consequences can be among the deadliest of all natural disasters. </p>
<p>The Nevado del Ruiz volcano in Colombia killed nearly 25,000 people in 1985 when its eruption caused the near-instantaneous melting of overlying glacier ice and snow, forming a deadly mix of water and eruptive material (mostly ash and gas) that hurtled down a populated valley at incredible speed. Glaciers on volcanoes are not only dangerous, they make monitoring volcanoes from the ground and from above using satellites particularly tricky.</p>
<figure class="align-center ">
<img alt="A mountainous scene with a large smoking crater covered in snow." src="https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&rect=0%2C0%2C799%2C501&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=377&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=377&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=377&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=473&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=473&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=473&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The crater of Nevado del Ruiz in 2023.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Nevado_del_Ruiz#/media/File:Volcan_Nevado_del_Ruiz-2023.png">Portal Servicio Geológico Colombiano</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Fortunately, in <a href="https://doi.org/10.1130/G51411.1">a new study</a>, we found that these glaciers can offer clues about what’s happening to the volcano below. This could help improve the monitoring of volcanoes that might erupt in the future.</p>
<h2>Hotting up</h2>
<p>Research has tentatively revealed that volcano temperatures change over time and <a href="https://www.nature.com/articles/s41561-021-00705-4">increase towards an eruption</a>. In some cases, these changes can be recorded over several years before visible unrest begins. It’s possible to monitor this via satellite, but the signal can be masked by clouds or disrupted by the ice or snow sitting on top of a volcano.</p>
<figure class="align-center ">
<img alt="A volcano spewing ash, seen from a distant grassland." src="https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.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">Vaporised snow and ash combine during eruptions of ice-clad volcanoes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/karimskiy-volcano-volcanic-eruption-kamchatka-ash-468722087">LukaKikina/Shutterstock</a></span>
</figcaption>
</figure>
<p>Although thought to move very slowly, glaciers are quite dynamic. These rivers of ice flow faster or slower depending on what’s happening in their environment. This may come as no surprise – most glaciers around the world are now shrinking due to rising global temperatures, and many will soon disappear.</p>
<p>But glaciers are sensitive to other changes too. For example, if a volcano’s temperature increases over time, the glacier sitting on it will melt faster and shrink to higher elevations. We thought this shrinking might indicate that something is brewing in the volcano below, so we analysed the elevation of 600 glaciers that either sat on or near (between 1km and 15km) 37 ice-clad volcanoes in South America using computer models. </p>
<figure class="align-center ">
<img alt="A volcano with an ice-covered summit seen from a distance." src="https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.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">Ice-clad Cotopaxi volcano in the Andes mountains, Ecuador.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cotopaxi-volcano-appears-clouds-light-snow-484202014">Ecuadorpostales/Shutterstock</a></span>
</figcaption>
</figure>
<p>Normally, elevation does not vary much from glacier to glacier within the same climate region. But our results showed that, in some cases, glacier elevation progressively decreases with distance from a volcano. In other words, glaciers further from a volcano tended to reach further down the mountain valley that hosted them.</p>
<p>The drop in glacier elevation moving away from a volcano can be as much as 600 metres. This is bigger than what we would expect to see with natural variation alone, especially for the relatively small glaciers we investigated. </p>
<h2>A sign from below</h2>
<p>Glaciers sitting on volcanoes are typically confined to higher elevations (230 metres higher, on average) compared with those nearby. Most importantly, our study showed that this difference is linked to measured volcanic temperatures: volcanoes with higher measured temperatures hosted glaciers at particularly high elevations.</p>
<p>This is really exciting because it paves the way for using glaciers to improve volcano monitoring. If the elevation of a glacier on top of a volcano changes over a short period (five to ten years, say), and the speed of this change cannot be attributed to climate change, it might signal a forthcoming period of volcanic unrest.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bylTVZFQOsE?wmode=transparent&start=1" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Glaciers sitting on volcanoes act as icy thermometers in volcano monitoring. This insight could help create early-warning systems capable of reducing the deadliness of erupting ice-clad volcanoes.</p>
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<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">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Matteo Spagnolo receives funding from NERC and the Leverhulme Trust. </span></em></p><p class="fine-print"><em><span>Brice Rea receives funding from NERC. </span></em></p><p class="fine-print"><em><span>Iestyn Barr receives funding from the Leverhulme Trust and NERC </span></em></p>Like icy thermometers, glaciers overlying volcanoes shift according to temperature changes below.Matteo Spagnolo, Professor of Geography and the Environment, School of Geosciences, University of AberdeenBrice Rea, Professor of Geography, University of AberdeenIestyn Barr, Reader in Physical Geography, Manchester Metropolitan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2062362023-08-21T15:40:48Z2023-08-21T15:40:48ZTo 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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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">
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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 UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2087372023-08-15T12:36:05Z2023-08-15T12:36:05ZThreat from climate change to some of India’s sacred pilgrimage sites is reshaping religious beliefs<figure><img src="https://images.theconversation.com/files/541580/original/file-20230807-675-omrts5.jpg?ixlib=rb-1.1.0&rect=36%2C0%2C3447%2C2310&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hindu devotees worship at the Kedarnath Temple in the northern Indian state of Uttarakhand. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/in-this-photograph-taken-on-june-16-indian-hindu-devotees-news-photo/698321918?adppopup=true">Shammi Mehra/AFP via Getty Images</a></span></figcaption></figure><p>The famous <a href="https://www.indiatoday.in/india/story/kedarnath-temple-opens-for-pilgrims-why-this-temple-in-uttarakhand-is-famous-1520807-2019-05-09">pilgrimage site of Kedarnath</a>, located in the central Himalayas of India, is believed to be a sacred land. It has been referred to as “deva bhumi,” or the “land of the gods,” for centuries. </p>
<p><a href="https://www.sacredyatra.com/chardham-yatra-pilgrim-stats.html">Millions of people visit this region</a> each year in search of divine blessings and other religious benefits as part of what is known as the Char Dham Yatra, or the pilgrimage to four sacred mountainous abodes devoted to different gods and goddesses. Situated at the base of 20,000-foot snowy peaks, Kedarnath is one of these four major destinations. </p>
<p>The mighty Hindu god Shiva is believed to have manifested in the middle of a meadow in Kedarnath as a conical rock formation that has long been worshiped as a lingam, an embodied form of the deity. A stone temple has stood over the lingam for at least a thousand years, at an altitude of about 12,000 feet.</p>
<p>I visited this area in 2000, 2014 and 2019 as part of research I’ve been conducting for decades on religion, nature and ecology; I have spent numerous summers in the Himalayas. Many in the vast crowds of people on the Char Dham Yatra told me that they believe it is important to undertake this pilgrimage at least once in their lifetime, often identifying it as the most significant journey they will ever perform.</p>
<p>But climate change now threatens the sacred sites of this region. As global temperatures rise, glaciers on the 20,000-foot peaks above Kedarnath that are key sources of the Mandakini River, a major tributary of the Ganges, are <a href="https://www.thecitizen.in/index.php/en/NewsDetail/index/13/21428/Rapid-Melt-of-Himalayan-Glaciers-Sounds-the-Alarm">melting and retreating at alarming rates</a>. In turn, as I argue in my book, “<a href="https://iupress.org/9780253056047/understanding-climate-change-through-religious-lifeworlds/">Understanding Climate Change through Religious Lifeworlds</a>,” climate change disasters are acting as powerful drivers of religious transformations, reshaping religious ideas and practices. </p>
<h2>Threats to the Himalayan region</h2>
<p>Glacial deterioration is happening worldwide, but subtropical glaciers in high mountainous areas such as the Indian Himalayas <a href="https://www.cbsnews.com/news/himalaya-glaciers-melting-faster-study-warns-will-affect-us-all">are more vulnerable</a> because of their low latitudes. Many climate scientists believe that climate change is affecting the Himalayas <a href="https://www.thethirdpole.net/en/climate/ignoring-climate-change-in-the-himalayas">more than almost any other region</a> of the world. </p>
<p>Melting glaciers leave massive amounts of water in lakes held in place by unstable natural dams formed of rubble heaped up when the glaciers were healthy and pushing down a slope. The expanding lakes left behind by shrinking glaciers are <a href="https://doi.org/10.1038/s41467-023-36033-x">increasingly prone to glacial lake outburst floods</a>. Another serious danger threatening high mountainous areas as a result of global warming is the <a href="https://doi.org/10.1038/s41586-023-06092-7">shift from snow to extreme rain</a> at increasingly higher altitudes. </p>
<p>Snow clings to hillsides and melts gradually, while rain rushes down slopes immediately, causing destructive erosion, landslides and deluges. The combination of extreme rain and glacial lake outburst floods can lead to deadly flooding, as demonstrated by a catastrophe in Kedarnath in 2013.</p>
<h2>Kedarnath disaster</h2>
<p>Himalayan researchers determined that in June 2013, <a href="https://www.researchgate.net/publication/269696415_Kedarnath_disaster_Facts_and_plausible_causes">more than a foot of rain fell</a> within 24 hours near Kedarnath at elevations never previously recorded. The entire watershed above Kedarnath was filled with raging water. Additionally, the Mandakini River burst out of its banks, causing landslides and devastating flooding. </p>
<figure class="align-center ">
<img alt="An aerial view showing buildings and erosion as a result of flooding in a town, located in a valley." src="https://images.theconversation.com/files/541582/original/file-20230807-1292-c8shsa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541582/original/file-20230807-1292-c8shsa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541582/original/file-20230807-1292-c8shsa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541582/original/file-20230807-1292-c8shsa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541582/original/file-20230807-1292-c8shsa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541582/original/file-20230807-1292-c8shsa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541582/original/file-20230807-1292-c8shsa.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">The Kedarnath Temple pictured amid flood destruction on June 18, 2013.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/the-kedarnath-temple-is-pictured-amid-flood-destruction-in-news-photo/170800919?adppopup=true">Strdel/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>To make matters worse, the rubble dam that had held back the glacial lake formed by the melting Chorabari Glacier above Kedarnath suddenly breached, releasing a high wall of crashing water. In a matter of 15 minutes, the entire content of the lake was emptied, cresting over three-story buildings with a pounding flow that University of Calcutta scientists estimated was <a href="https://e360.yale.edu/features/unnatural_disaster_how_global_warming_helped_cause_indias_catastrophic_flood#:%7E:text=Global%20warming%20has%20is%20also,pulse%20of%20debris%2Dfilled%20water">half the volume of Niagara Falls</a>. </p>
<p>Fortunately – or, according to pilgrims, miraculously – a 30-foot oblong boulder rolled down the mountain and stopped just before the ancient temple, parting the powerful waters and protecting the temple so that it remained standing without major damage. Every other building in the town of Kedarnath was demolished. </p>
<p>Government figures claim over 6,000 people died, but those <a href="https://www.freepressjournal.in/india/2013-kedarnath-flood-disaster-how-a-cloudburst-killed-6000-people-9-years-ago">involved in the rescue operations set the figure much higher</a>. Most of the dead were pilgrims.</p>
<h2>‘The Gods are angry’</h2>
<p>The destructive flooding is changing people’s beliefs. The gods of this region are closely associated with the land itself; and these gods, nature and humans are intimately connected. People living in this region understand the dramatic changes taking place here in terms of this triad. </p>
<p><a href="https://iupress.org/9780253056047/understanding-climate-change-through-religious-lifeworlds/">A resident of Gangotri explained</a>, “The gods are angry with us because of how we are now acting.” When I said to him that I thought this area is where people have been coming for a long time to receive the blessing from the gods, he responded, “Yes, but now they are angry with us. That is why this (Kedarnath disaster) has happened. And more will come if we do not change our ways.” </p>
<p>I found this to be a common view – weather-related disasters were being understood as a result of the immoral actions of human beings, particularly the disregard for the environment. </p>
<p>One significant theological change that appeared to be underway within Himalayan Hinduism as a result of climate change was the transformation of the primary conception of the gods from those who bless to those who punish. “There is so much sin in the world today,” <a href="https://iupress.org/9780253056047/understanding-climate-change-through-religious-lifeworlds/">a resident of Uttarkashi told me</a>. “People are making a lot of pollution. Because of this, the climate is changing and the gods are beginning to punish us.” </p>
<p>In some ways there is nothing new in the assertion that human morality and the environment are intimately linked, but the degree of change that is now happening has introduced a new level of concern. </p>
<p>Wandering holy men in this region are witnessing firsthand the dramatic changes in the Himalayas during their years of travel. One holy man living in this area explained, “The gods are nature. When we disrespect nature, <a href="https://iupress.org/9780253056047/understanding-climate-change-through-religious-lifeworlds/">we disrespect the gods</a>. They are now angry because of what we are doing to nature. This is why the destructive storms are increasing.” </p>
<h2>Conditional hope</h2>
<p>All is not lost, however, and there remains some hope for a better outcome. There is a sense that things can still be turned around and the worst avoided if humans are willing to change their ways. Specifically, many articulated this as a return to a more respectful relationship with the gods of the land. </p>
<p>When asked how to please the gods and turn things around, a man in Kedarnath put it simply: “To once again respect the land and nature.” There is no great difference between treating the gods with respect and nature well. <a href="https://iupress.org/9780253056047/understanding-climate-change-through-religious-lifeworlds/">A woman I spoke to in Uttarkashi elaborated</a> on this: “The gods and the land are the same. And we are mistreating both. The floods are like a warning slap to a child. They are a wake-up call telling us to change our ways. … If not, we will be finished.”</p>
<p>Human behavior remains a major factor in the holistic worldview that connects humans, gods and environment, and a return to respectful relationships is the key to a sustainable future. </p>
<p>Many Himalayan residents say that humans have the choice to return to a more mutually beneficial relationship with the natural world, but if the gods’ stormy warnings are not heeded, then massive destruction and a gruesome end is near. </p>
<h2>Uncertain future</h2>
<p>Destructive floods continue to happen in the central Himalayas with increasing <a href="https://news.climate.columbia.edu/2021/02/16/flood-himalayas-development-climate/">force and frequency</a>. Since the 2013 disaster at Kedarnath, more than 800 people have been killed in <a href="https://economictimes.indiatimes.com/news/india/uttarakhand-a-land-ravaged-by-natural-disasters/articleshow/92630543.cms?from=mdr">flash floods in the Char Dham region</a>. </p>
<p>The Kedarnath pilgrimage was <a href="https://www.livemint.com/news/india/kedarnath-yatra-2022-suspended-due-to-heavy-rains-in-uttarakhand-details-here-11657359453169.html">suspended in 2022</a> because of deadly landslides and flooding, but the Indian government has also heavily promoted religious tourism in this area. The <a href="https://www.thehindu.com/news/national/other-states/char-dham-yatra-sees-record-footfall-this-year/article66001254.ece">year 2022 saw a record number of pilgrims</a> visiting Kedarnath and the three other Char Dham sites in the central Himalayas, which only puts more stress on the land, with additional buildings, crowded roads and polluting vehicles.</p>
<p>With vehicles, factories and other human activities continuing to pump excessive amounts of greenhouse gases into the atmosphere, warming the planet, <a href="https://www.nature.com/articles/s41558-020-0855-4">experts fear</a> disasters like Kedarnath saw in 2013 <a href="https://www.nature.com/articles/s41467-023-36033-x">will become only more common</a>.</p><img src="https://counter.theconversation.com/content/208737/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David L. Haberman receives funding from American Institute of India Studies (AIIS). I received a grant from AIIS to research the effects of climate change related disasters on the religious site of Kedarnath and the other Char Dham sites. the summer months of 2019.</span></em></p>At the pilgrimage site of Kedarnath in northern India, disastrous flooding has led many to ask whether the gods are getting angry about human behavior.David L. Haberman, Professor Emeritus, Religious Studies, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2108412023-08-08T14:58:15Z2023-08-08T14:58:15ZHow climate change might trigger more earthquakes and volcanic eruptions<figure><img src="https://images.theconversation.com/files/541708/original/file-20230808-21-64ruai.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2423%2C2337&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A volcanic eruption at the Reykjanes peninsula in Iceland in May 2021.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/geldingadalir-iceland-may-11-2021-small-1973100038">Thorir Ingvarsson/Shutterstock</a></span></figcaption></figure><p>Earth’s climate is changing rapidly. In some areas, escalating temperatures are increasing the frequency and likelihood of <a href="https://link.springer.com/article/10.1007/s10584-022-03409-9">wildfires and drought</a>. In others, they are making <a href="https://www.nature.com/articles/s41598-020-70816-2">downpours</a> and <a href="https://tyndall.ac.uk/wp-content/uploads/2021/03/sciencebrief_review_cyclones_mar2021.pdf">storms</a> more intense or accelerating the pace of glacial melting.</p>
<p>The past month is a stark illustration of exactly this. <a href="https://www.bbc.co.uk/news/world-europe-66435160">Parts of Europe</a> and <a href="https://www.reuters.com/graphics/CANADA-WILDFIRE/HISTORIC/znvnzebmavl/">Canada</a> are being devastated by wildfires, while Beijing has recorded <a href="https://apnews.com/article/china-beijing-rainfall-floods-1a8f968799bd539d11f3421010b8f2a9">its heaviest rainfall</a> in at least 140 years. Looking back further, between 2000 and 2019 the world’s glaciers lost around <a href="https://www.nature.com/articles/s41586-021-03436-z">267 gigatonnes of ice</a> per year. Melting glaciers contribute to rising sea levels (currently rising by about <a href="https://climate.copernicus.eu/climate-indicators/sea-level">3.3mm per year</a>) and more coastal hazards such as flooding and erosion.</p>
<p>But research suggests that our changing climate may not solely influence hazards at the Earth’s surface. Climate change – and specifically rising rainfall rates and glacial melting – could also exacerbate dangers beneath the Earth’s surface, such as earthquakes and volcanic eruptions.</p>
<p>Drought in <a href="https://news.sky.com/story/nearly-half-of-european-union-land-slides-into-drought-12921475">Europe</a> and <a href="https://www.ncei.noaa.gov/news/us-drought-weekly-report-august-1-2023">North America</a> has received a lot of recent media coverage. But the Intergovernmental Panel on Climate Change’s <a href="https://www.ipcc.ch/report/ar6/wg1/">Sixth Assessment Report</a> in 2021 revealed that average rainfall has actually increased in many world regions since 1950. A warmer atmosphere can retain more water vapour, subsequently leading to higher levels of precipitation.</p>
<p>Interestingly, geologists have long <a href="https://www.newscientist.com/article/dn13371-heavy-rain-can-trigger-earthquakes/">identified a relationship</a> between rainfall rates and seismic activity. In the Himalayas, for example, the <a href="http://tectonics.caltech.edu/publications/pdf/bettinelli_avouacEPSLfeb08.pdf">frequency of earthquakes</a> is influenced by the annual rainfall cycle of the summer monsoon season. <a href="https://www.sciencedirect.com/science/article/pii/S1674984722000404">Research</a> reveals that 48% of Himalayan earthquakes strike during the drier pre-monsoon months of March, April and May, while just 16% occur in the monsoon season.</p>
<p>During the summer monsoon season, the weight of up to 4 metres of rainfall compresses the crust both vertically and horizontally, stabilising it. When this water disappears in the winter, the effective “rebound” destabilises the region and increases the number of earthquakes that occur. </p>
<p><strong>The number of earthquakes that occurred seasonally from 2003-2020</strong></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graph showing the seasonal fluctuation in earthquake occurrence with more earthquakes happening pre-monsoon." src="https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=160&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=160&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=160&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=201&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=201&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=201&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In the pre-monsoon period, the number of earthquakes increases.</span>
<span class="attribution"><a class="source" href="https://creativecommons.org/licenses/by-nc-nd/4.0/">Shashikant Nagale et al. (2022)/Geodesy and Geodynamics</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Climate change could intensify this phenomenon. <a href="https://www.science.org/doi/10.1126/sciadv.abg3848">Climate models</a> project that the intensity of monsoon rainfall in southern Asia will increase in the future as a result of climate change. This could feasibly enhance the winter rebound and cause more seismic events. </p>
<p>The impact of water’s weight on the Earth’s crust goes beyond just precipitation; it extends to glacial ice as well. As the last ice age came to an end roughly 10,000 years ago, the thawing of heavy glacial ice masses caused parts of the Earth’s crust to rebound upwards. This process, called <a href="https://www.newscientist.com/article/mg17723774-900-the-word-isostatic-rebound/">isostatic rebound</a>, is evidenced by raised beaches in Scotland – some of which are up to 45 metres above current sea level. </p>
<p><a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL069359">Evidence from Scandinavia</a> suggests that such uplift, coupled with the destabilisation of the region’s tectonics, triggered numerous earthquake events between 11,000 and 7,000 years ago. Some of these earthquakes even exceeded a magnitude of 8.0 which indicates <a href="https://www.britannica.com/science/Richter-scale">severe destruction and loss of life</a>. The concern is that the continued melting of glacial ice today could result in similar effects elsewhere.</p>
<figure class="align-center ">
<img alt="Raised beaches at Tongue Bay, Scotland." src="https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?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">
<figcaption>
<span class="caption">Raised beaches at Tongue Bay in Scotland.</span>
<span class="attribution"><a class="source" href="https://www.geos.ed.ac.uk/~rsgs/ifa/gems/landformraisedbeach.html">Patrick Bailey/Royal Scottish Geographical Society</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>How about volcanic activity?</h2>
<p><a href="https://pubs.geoscienceworld.org/gsa/geology/article/46/1/47/521232/Climatic-control-on-Icelandic-volcanic-activity">Research</a> has also found a correlation between glacial-load changes on the Earth’s crust and the occurrence of volcanic activity. Approximately 5,500–4,500 years ago, Earth’s climate briefly cooled and glaciers began to expand in Iceland. Analysis of volcanic ash deposits spread throughout Europe suggest that volcanic activity in Iceland markedly reduced during this period. </p>
<p>There was a subsequent increase in volcanic activity following the end of this cool period, albeit with a delay of several hundred years. </p>
<p>This phenomenon can be explained by the weight of glaciers compressing both the Earth’s crust and the underlying mantle (the mostly solid bulk of Earth’s interior). This kept the material that makes up the mantle under higher pressure, preventing it from melting and forming the magma required for volcanic eruptions. </p>
<p>However, deglaciation and the associated loss of weight on the Earth’s surface allowed a process called <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GC008222">decompression melting</a> to occur, where lower pressure facilitates melting in the mantle. Such melting resulted in the formation of the liquid magma that fuelled the subsequent volcanic activity in Iceland. </p>
<p>Even today, this process is responsible for driving some volcanic activity in Iceland. Eruptions at two volcanoes, Grímsvötn and Katla, <a href="https://academic.oup.com/gji/article/181/3/1510/604035?login=false">consistently occur during the summer period</a> when glaciers retreat.</p>
<p>It is therefore feasible that ongoing glacial retreat due to global warming could potentially increase volcanic activity in the future. However, the time lag between glacial changes and the volcanic response is reassuring for now. </p>
<figure class="align-center ">
<img alt="The Katla volcano covered by the Mýrdalsjökull glacier." src="https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=318&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=318&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=318&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=400&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=400&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=400&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Katla volcano covered by the Mýrdalsjökull glacier.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/katla-volcano-glacier-iceland-2287047711">muratart/Shutterstock</a></span>
</figcaption>
</figure>
<p>The impacts of a changing climate are becoming more evident, with unusual weather events having become the norm rather than the exception. However, the indirect impacts of climate change on the ground beneath our feet are neither widely known or discussed. </p>
<p>This must change if we are to minimise the effects of the changing climate that have already been set firmly in motion.</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>Matthew Blackett 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>Climate change is causing increasingly severe weather – but it’s not just hazards at the Earth’s surface we should be concerned about.Matthew Blackett, Reader in Physical Geography and Natural Hazards, Coventry UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2074682023-06-29T12:17:15Z2023-06-29T12:17:15ZMeltwater 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 TromsøLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2073552023-06-28T15:12:36Z2023-06-28T15:12:36ZFrom 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>
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<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">
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<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 BrightonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2077852023-06-23T15:51:06Z2023-06-23T15:51:06ZThe 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>
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<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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<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 UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2074342023-06-14T11:31:22Z2023-06-14T11:31:22ZLimiting global warming to 2°C is not enough – why the world must keep temperature rise below 1°C<figure><img src="https://images.theconversation.com/files/531401/original/file-20230612-264036-d3q307.jpg?ixlib=rb-1.1.0&rect=599%2C161%2C3705%2C2829&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Warming of more than 1℃ risks unsafe and harmful outcomes for humanity.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/people-banners-protest-part-climate-change-1341939314">Ink Drop/Shutterstock</a></span></figcaption></figure><p>The Paris Climate agreement represented a historic step towards a safer future for humanity on Earth when it was adopted in 2015. The agreement strove to keep global heating <a href="https://unfccc.int/process-and-meetings/the-paris-agreement">below 2°C above pre-industrial levels</a> with the aim of limiting the increase to 1.5°C if possible. It was signed by 196 parties around the world, representing the overwhelming majority of humanity.</p>
<p>But in the intervening eight years, the Arctic region has experienced <a href="https://theconversation.com/siberia-heatwave-why-the-arctic-is-warming-so-much-faster-than-the-rest-of-the-world-141455">record-breaking temperatures</a>, heatwaves have <a href="https://en.wikipedia.org/wiki/2023_Asia_heat_wave">gripped many parts of Asia</a> and Australia has faced <a href="https://www.climatecouncil.org.au/resources/powder-keg-australia-primed-to-burn/">unprecedented floods and wildfires</a>. These events remind us of the dangers associated with climate breakdown. <a href="https://doi.org/10.1371/journal.pclm.0000234">Our newly published research</a> argues instead that humanity is only safe at 1°C of global warming or below.</p>
<p>While one extreme event cannot be solely attributed to global heating, <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-earth-071719-055228">scientific studies</a> have shown that such events are much more likely in a warmer world. Since the Paris agreement, our understanding of the impacts of global heating <a href="https://www.ipcc.ch/report/ar6/wg1/">have also improved</a>.</p>
<figure class="align-center ">
<img alt="A fishing boat surrounded by icebergs that have come off a glacier." src="https://images.theconversation.com/files/531386/original/file-20230612-151816-2k49z8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531386/original/file-20230612-151816-2k49z8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531386/original/file-20230612-151816-2k49z8.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531386/original/file-20230612-151816-2k49z8.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531386/original/file-20230612-151816-2k49z8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531386/original/file-20230612-151816-2k49z8.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531386/original/file-20230612-151816-2k49z8.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">Fishing boat dwarfed by icebergs that came off Greenland’s largest glacier, Jakobshavn Isbrae.</span>
<span class="attribution"><span class="source">Jonathan Bamber</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Rising sea levels are an inevitable consequence of global warming. This is due to the combination of increased land ice melting and warmer oceans, which cause the volume of ocean water to increase. <a href="https://doi.org/10.1029/2022EF002696">Recent research</a> shows that in order to eliminate the human-induced component of sea-level rise, we need to return to temperatures last seen in the pre-industrial era (usually taken to be around 1850). </p>
<p>Perhaps more worrying are tipping points in the climate system that are effectively irreversible on human timescales if passed. Two of these tipping points relate to the melting of the <a href="https://www.britannica.com/place/Greenland-Ice-Sheet">Greenland</a> and <a href="https://www.antarcticglaciers.org/antarctica-2/west-antarctic-ice-sheet-2/west-antarctic-ice-sheet/">West Antarctic ice sheets</a>. Together, these sheets contain enough ice to raise the global sea level by <a href="https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/">more than ten metres</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/greenland-is-melting-we-need-to-worry-about-whats-happening-on-the-largest-island-in-the-world-150261">Greenland is melting: we need to worry about what’s happening on the largest island in the world</a>
</strong>
</em>
</p>
<hr>
<p>The temperature threshold for these ice sheets is uncertain, but we know that it lies close to 1.5°C of global heating above pre-industrial era levels. There’s even evidence that suggests the threshold may <a href="https://doi.org/10.1126/science.1249055">already have been passed</a> in one part of west Antarctica.</p>
<h2>Critical boundaries</h2>
<p>A temperature change of 1.5°C might sound quite small. But it’s worth noting that the rise of modern civilisation and the agricultural revolution some 12,000 years ago took place during a period of exceptionally stable temperatures. </p>
<p>Our food production, global infrastructure and ecosystem services (the goods and services provided by ecosystems to humans) are all intimately tied to that stable climate. For example, <a href="https://doi.org/10.1126/science.1177303">historical evidence</a> shows that a period called the little ice age (1400-1850), when glaciers grew extensively in the northern hemisphere and <a href="https://en.wikipedia.org/wiki/River_Thames_frost_fairs">frost fairs</a> were held annually on the River Thames, was caused by a much smaller temperature change of only about 0.3°C. </p>
<figure class="align-center ">
<img alt="A sign marking the retreat of a glacier since 1908." src="https://images.theconversation.com/files/531399/original/file-20230612-256771-qizq78.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531399/original/file-20230612-256771-qizq78.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531399/original/file-20230612-256771-qizq78.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531399/original/file-20230612-256771-qizq78.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531399/original/file-20230612-256771-qizq78.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531399/original/file-20230612-256771-qizq78.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531399/original/file-20230612-256771-qizq78.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">
<figcaption>
<span class="caption">Jasper National Park, Canada. Glaciers used to grow extensively in the Northern Hemisphere.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/location-date-marker-glacier-jasper-national-81823690">Matty Symons/Shutterstock</a></span>
</figcaption>
</figure>
<p>A <a href="https://doi.org/10.1038/s41586-023-06083-8">recent review of the current research in this area</a> introduces a concept called “Earth system boundaries”, which defines various thresholds beyond which life on our planet would suffer substantial harm. To avoid passing multiple critical boundaries, the authors stress the need to limit temperature rise to 1°C or less.</p>
<p>In our new research, we also argue that warming of more than 1°C risks unsafe and harmful outcomes. This potentially includes sea level rise of multiple metres, more intense hurricanes and more frequent weather extremes. </p>
<h2>More affordable renewable energy</h2>
<p>Although we are already at <a href="https://www.ipcc.ch/report/ar6/syr/">1.2°C above</a> pre-industrial temperatures, reducing global temperatures is not an impossible task. Our research presents a roadmap based on current technologies that can help us work towards achieving the 1°C warming goal. We do not need to pull a technological “rabbit out of the hat”, but instead we need to invest and implement existing approaches, such as renewable energy, at scale. </p>
<p>Renewable energy sources have become increasingly affordable over time. Between 2010 and 2021, the <a href="https://www.irena.org/publications/2022/Jul/Renewable-Power-Generation-Costs-in-2021">cost of producing electricity</a> from solar energy reduced by 88%, while wind power saw a reduction of 67% over the same period. The cost of <a href="https://www.irena.org/publications/2022/Jul/Renewable-Power-Generation-Costs-in-2021">power storage in batteries</a> (for when the availability of wind and sunlight is low) has also decreased, by 70% between 2014 and 2020. </p>
<figure class="align-center ">
<img alt="An aerial photograph of a photovoltaic power plant on a lush hillside." src="https://images.theconversation.com/files/531393/original/file-20230612-150594-30jq03.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531393/original/file-20230612-150594-30jq03.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531393/original/file-20230612-150594-30jq03.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531393/original/file-20230612-150594-30jq03.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531393/original/file-20230612-150594-30jq03.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531393/original/file-20230612-150594-30jq03.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531393/original/file-20230612-150594-30jq03.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">A photovoltaic power plant in Yunnan, China.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/eryuan-county-dali-yunnan-china-september-1946670307">Captain Wang/Shutterstock</a></span>
</figcaption>
</figure>
<p>The cost disparity between renewable energy and alternative sources like nuclear and fossil fuels <a href="https://www.lazard.com/research-insights/2023-levelized-cost-of-energyplus/">is now huge</a> – there is a three to four-fold difference. </p>
<p>In addition to being affordable, renewable energy sources are abundantly available and could swiftly <a href="https://www.ise.fraunhofer.de/en/publications/featured-publications/science-vol-380.html">meet society’s energy demands</a>. Massive capacity expansions are also currently underway across the globe, which will only further bolster the renewable energy sector. Global solar energy manufacturing capacity, for example, is <a href="https://www.iea.org/reports/renewable-energy-market-update-june-2023/is-there-enough-global-wind-and-solar-pv-manufacturing-to-meet-net-zero-targets-in-2030">expected to double</a> in 2023 and 2024. </p>
<h2>Removing carbon dioxide from the atmosphere</h2>
<p>Low-cost renewable energy will enable our energy systems to <a href="https://www.sciencedirect.com/science/article/pii/S0360544223005935">transition away from fossil fuels</a>. But it also provides the means of directly removing CO₂ from the atmosphere at a large scale. </p>
<p>CO₂ removal is crucial for keeping warming to 1°C or less, even though it requires a significant amount of energy. According to research, achieving a safe climate would require dedicating <a href="https://www.sciencedirect.com/science/article/pii/S0360544223005935">between 5% and 10%</a> of total power generation demand to effective CO₂ removal. This represents a realistic and attainable policy option.</p>
<p>Various measures are used to remove CO₂ from the atmosphere. These include nature-based solutions like reforestation, as well as direct air carbon capture and storage. Trees absorb CO₂ from the atmosphere through photosynthesis and then lock it up for centuries.</p>
<figure class="align-center ">
<img alt="A group of people planting a mangrove forest next to the sea." src="https://images.theconversation.com/files/531394/original/file-20230612-119811-fxe7ax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531394/original/file-20230612-119811-fxe7ax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531394/original/file-20230612-119811-fxe7ax.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531394/original/file-20230612-119811-fxe7ax.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531394/original/file-20230612-119811-fxe7ax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531394/original/file-20230612-119811-fxe7ax.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531394/original/file-20230612-119811-fxe7ax.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 mangrove forest being planted in Klong Khone Samut Songkhram Province, Thailand.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/reforestation-mangrove-forest-klong-khone-samut-664048141">vinai chunkhajorn/Shutterstock</a></span>
</figcaption>
</figure>
<p>Direct air capture technology was originally developed in the 1960s for air purification on submarines and spacecrafts. But it has since been further adapted for use on land. When combined with underground storage methods, such as the process of <a href="https://www.carbfix.com/">converting CO₂ into stone</a>, this technology provides a safe and permanent method of removing CO₂ from the atmosphere.</p>
<p>Our paper demonstrates that the tools and technology exist to achieve a safer, healthier and more prosperous future – and that it’s economically viable to do so. What appears to be lacking is the societal will and, as a consequence, the political conviction and commitment to achieve it.</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>
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Jonathan Bamber receives funding from the UK Natural Environment and Engineering and Physical Sciences Research Councils, the European Commission, the European Research Council and the European Space Agency.</span></em></p><p class="fine-print"><em><span>Christian Breyer receives funding from public research funding: Academy of Finland, Business Finland, Horizon Europe, and is employed at the public LUT University in Finland. </span></em></p>Temperature rise of more than 1°C pushes us towards irreversible climate tipping points, yet Earth is 1.2°C warmer than in pre-industrial times.Jonathan Bamber, Professor of Glaciology and Earth Observation, University of BristolChristian Breyer, Professor of Solar Economy, Lappeenranta University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2053442023-05-17T16:23:54Z2023-05-17T16:23:54ZMelting glaciers in the Alps will eradicate some invertebrates that are crucial for alpine ecosystems – new research<figure><img src="https://images.theconversation.com/files/526783/original/file-20230517-13420-fhpzvb.JPG?ixlib=rb-1.1.0&rect=306%2C180%2C2463%2C1661&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A glacier-fed river from the Odenwinkelkees glacier, Austria.</span> <span class="attribution"><span class="source">Jonathan Carrivick</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Glaciers across the European Alps are melting at an alarming rate. Between 2000 and 2014, glaciers in the region <a href="https://www.nature.com/articles/s41467-020-16818-0">thinned by up to 0.9 metres</a> on average each year. Over the entire mountain range, this rate of melting produces around 1.3 gigatonnes of lost ice mass annually. </p>
<p>The rapid decline of these glaciers poses a significant threat to the many animal species that live in or around the glacial meltwater rivers of the Alps. Invertebrates that are specially adapted to living in these rivers, for example, will face widespread habitat loss in the future should these rivers decline.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/526784/original/file-20230517-25-7w0x3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A multi-panel image of the invertebrate species included in the study." src="https://images.theconversation.com/files/526784/original/file-20230517-25-7w0x3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/526784/original/file-20230517-25-7w0x3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=914&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526784/original/file-20230517-25-7w0x3f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=914&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526784/original/file-20230517-25-7w0x3f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=914&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526784/original/file-20230517-25-7w0x3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1149&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526784/original/file-20230517-25-7w0x3f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1149&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526784/original/file-20230517-25-7w0x3f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1149&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 invertebrate species included in the study.</span>
<span class="attribution"><span class="source">Bertrand Launay</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>And invertebrates are crucial for wider alpine ecosystems. They perform <a href="https://academic.oup.com/bioscience/article/49/2/119/239602">vital roles in nutrient cycling</a> and, as prey for fish, amphibians, birds and mammals, they transfer organic matter from lower to higher levels of the food chain.</p>
<p>In our <a href="https://www.nature.com/articles/s41559-023-02061-5">new study</a>, we projected glacial losses between 2020 and 2100 to assess what impact the changing input of meltwater into alpine rivers would have on the distribution of 15 species of invertebrate, such as stoneflies, non-biting midges, flatworms and mayflies.</p>
<p>We found that some species will lose most of their habitat and disappear from the Alps entirely. Several other species will have to move to cold water habitats at higher elevations where glaciers still persist to survive. </p>
<h2>Future melting</h2>
<p>To generate our projections, we used glacier, landscape and biodiversity mapping data collected across 34,000 sq km of the Alps. We <a href="https://www.frontiersin.org/articles/10.3389/feart.2015.00054/full">modelled glacier evolution</a> based on the greenhouse gas emissions scenario that is currently targeted by governments and international treaties (limiting global warming to 2°C).</p>
<p>We then developed 3D landscape models for each decade, and mapped how changes to glaciers will affect river flow conditions as the input of glacial melt decreases. Water temperature increases as glacier melt inputs to rivers fall and river banks become less prone to erosion. Both of these are important factors in determining aquatic species abundance and <a href="https://www.nature.com/articles/s41559-017-0426-x">diversity in glacier-fed rivers</a>.</p>
<p>Using our models, we simulated key invertebrate populations for each decade between now and 2100. We then predicted the future distribution of these species across the Alps by using data from previous invertebrate monitoring studies, as well as key environmental characteristics of the glacier-fed rivers.</p>
<h2>Consequences for invertebrates</h2>
<p>Our results, recently published in <a href="https://www.nature.com/articles/s41559-023-02061-5">Nature Ecology and Evolution</a>, show that rivers across the Alps will experience major change by the end of the century. Until 2040, some will carry more water and new tributary rivers will form. But after that, most glacial rivers will become drier, warmer, flow slower and less prone to erosion. Some streams could even endure periods in a year where there is no water flow at all. </p>
<figure class="align-center ">
<img alt="A meltwater river flowing out of a glacial valley." src="https://images.theconversation.com/files/526782/original/file-20230517-11997-4mx9pf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/526782/original/file-20230517-11997-4mx9pf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=599&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526782/original/file-20230517-11997-4mx9pf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=599&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526782/original/file-20230517-11997-4mx9pf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=599&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526782/original/file-20230517-11997-4mx9pf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=753&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526782/original/file-20230517-11997-4mx9pf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=753&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526782/original/file-20230517-11997-4mx9pf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=753&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Meltwater flow from a glacier in the Sulzbach valley, Austria.</span>
<span class="attribution"><span class="source">Lee Brown</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>These changes will all have severe consequences for aquatic invertebrates. </p>
<p>Our models suggest that the hardest-hit species will be some non-biting midges, stoneflies and mayflies. The habitat conditions in which some of these species thrive will become very rare and small in extent. To avoid extinction, it is likely that cold water specialists such as the non-biting midge species <em>Diamesa steinboecki</em> will have to migrate to higher parts of the Alps where glaciers persist.</p>
<p>Some of these species may be lost from the rivers entirely. Invertebrates that live on the rivers that flow into the Danube river basin are particularly vulnerable. Our projections suggest the glaciers that feed these rivers will be lost completely in the future. </p>
<p>But it’s far from a simple picture. Several species, including the flatworm <em>Crenobia alpina</em>, could benefit from the habitat changes because they thrive in warmer and more stable river flows. </p>
<p>Some mayflies, such as <em>Rhithrogena loyolaea</em>, are less at risk of habitat loss because they can tolerate mixtures of glacial- and groundwater-fed river conditions. However, a closely related mayfly species, <em>Rhithrogena nivata</em>, appears to be at higher risk if glaciers are lost completely.</p>
<h2>Competing interests</h2>
<p>Higher and colder parts of the Alps will provide refuge for some invertebrate species in the future. However, it is these areas that are also likely to see increasing pressure from <a href="https://doi.org/10.1659/0276-4741(2001)021%5B0335:TVOTSI%5D2.0.CO;2">skiing</a> and other winter activities, as finding cold and snow becomes harder. As glacial rivers decline, higher parts of the mountain range could also become hotspots for hydropower.</p>
<figure class="align-center ">
<img alt="A skier skiing on fresh powder snow." src="https://images.theconversation.com/files/526764/original/file-20230517-27-qe6olr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/526764/original/file-20230517-27-qe6olr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=394&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526764/original/file-20230517-27-qe6olr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=394&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526764/original/file-20230517-27-qe6olr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=394&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526764/original/file-20230517-27-qe6olr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=496&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526764/original/file-20230517-27-qe6olr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=496&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526764/original/file-20230517-27-qe6olr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=496&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Pockets of ice in the high Alps will be subject to intense competition.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/full-length-skier-skiing-on-fresh-144827767">sirtravelalot/Shutterstock</a></span>
</figcaption>
</figure>
<p>Some of the invertebrate species that will seek refuge in these areas may have pharmaceutical or commercial applications that are at present unknown. Invertebrate species that specialise in cold water habitats, for example, have evolutionary adaptations (such as antifreeze proteins) that enable them to survive low temperatures. </p>
<p>Conservation strategies are thus needed to protect this threatened alpine biodiversity from human interference in the future. At present, these important high alpine areas are often not included within national park boundaries.</p>
<p>Predicting how invertebrate populations respond to climate change is key to understanding how biodiversity in high mountain areas will be affected. We focused on just a handful of species and entirely on the European Alps. But the techniques we used could be applied to other mountain environments, while advances in environmental DNA sample collection and analysis offer the promise of understanding how glacier loss will affect thousands of other species – from bacteria and fungi to invertebrates, fish and birds.</p><img src="https://counter.theconversation.com/content/205344/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The UK’s Natural Environment Research Council contributed to the funding of this study.</span></em></p><p class="fine-print"><em><span>Lee Brown receives funding from NERC, Royal Geographical Society, EU</span></em></p><p class="fine-print"><em><span>Martin Wilkes 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>Meltwater rivers in the European Alps will change as glaciers melt – threatening animals that are vital for alpine ecosystems with habitat loss.Jonathan L. Carrivick, Senior Lecturer in Geomorphology, University of LeedsLee Brown, Professor of Aquatic Science, University of LeedsMartin Wilkes, Senior Lecturer of Life Sciences, University of EssexLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2032772023-04-06T11:24:18Z2023-04-06T11:24:18ZNew research shows how rapidly ice sheets can retreat – and what it could mean for Antarctic melting<figure><img src="https://images.theconversation.com/files/519798/original/file-20230406-20-zctnfl.jpg?ixlib=rb-1.1.0&rect=38%2C6%2C4272%2C2833&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A glacier in Paradise Bay, Antarctica.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/glacier-paradise-bay-antarctica-2227007003">jet 67/Shutterstock</a></span></figcaption></figure><p>The <a href="https://www.bas.ac.uk/about/antarctica/geography/ice/">Antarctic Ice Sheet</a>, which covers an area greater than the US and Mexico combined, holds enough water to raise global sea level by <a href="https://www.nature.com/articles/s41561-019-0510-8">more than 57 metres if melted completely</a>. This would flood hundreds of cities worldwide. And evidence suggests it is melting fast. Satellite observations have revealed that grounded ice (ice that is in contact with the bed beneath it) in coastal areas of West Antarctica has been lost at a rate of <a href="https://www.nature.com/articles/s41561-021-00877-z">up to 30 metres per day</a> in recent years. </p>
<p>But the satellite record of ice sheet change is relatively short as there are only 50 years’ worth of observations. This limits our understanding of how ice sheets have evolved over longer periods of time, including the maximum speed at which they can retreat and the parts that are most vulnerable to melting. </p>
<p>So, we set out to investigate how ice sheets responded during a previous period of climatic warming – the last “deglaciation”. This climate shift occurred between roughly 20,000 and 11,000 years ago and spanned Earth’s transition from a glacial period, when ice sheets covered large parts of Europe and North America, to the period in which we currently live (called the <a href="https://www.ncei.noaa.gov/sites/default/files/2021-11/12%20Mid-Holocene%20Warm%20Period%20%26%20Penultimate%20Interglacial%20Period%20%26%20Early%20Eocene%20Period%20-FINAL%20OCT%202021.pdf">Holocene interglacial period</a>). </p>
<p>During the last deglaciation, rates of temperature and sea-level rise were broadly comparable to today. So, studying the changes to ice sheets in this period has allowed us to estimate how Earth’s two remaining ice sheets (Greenland and Antarctica) might respond to an even warmer climate in the future.</p>
<p>Our <a href="https://www.nature.com/articles/s41586-023-05876-1">recently published results</a> show that ice sheets are capable of retreating in bursts of up to 600 metres per day. This is much faster than has been observed so far from space.</p>
<figure class="align-center ">
<img alt="A satellite image showing blocks of ice floating in the ocean." src="https://images.theconversation.com/files/519800/original/file-20230406-26-vgkg3h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519800/original/file-20230406-26-vgkg3h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519800/original/file-20230406-26-vgkg3h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519800/original/file-20230406-26-vgkg3h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519800/original/file-20230406-26-vgkg3h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519800/original/file-20230406-26-vgkg3h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519800/original/file-20230406-26-vgkg3h.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">
<figcaption>
<span class="caption">Satellite imagery reveals that Earth’s ice sheets are retreating fast.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/glacier-greenland-blocks-ice-floating-ocean-1750617149">Trismegist san/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Pulses of rapid retreat</h2>
<p>Our research used <a href="https://mareano.no/en">high-resolution maps</a> of the Norwegian seafloor to identify small landforms called “corrugation ridges”. These 1–2 metre high ridges were produced when a former ice sheet retreated during the last deglaciation. </p>
<p>Tides lifted the ice sheet <a href="https://www.science.org/doi/10.1126/science.aaz3059">up and down</a>. At low tide, the ice sheet rested on the seafloor, which pushed the sediment at the edge of the ice sheet upwards into ridges. Given that there are two low tides each day off Norway, two separate ridges were produced daily. Measuring the space between these ridges enabled us to calculate the pace of the ice sheet’s retreat. </p>
<p>During the last deglaciation, the <a href="https://www.britannica.com/place/Scandinavian-Ice-Sheet">Scandinavian Ice Sheet</a> that we studied underwent pulses of extremely rapid retreat – at rates between 50 and 600 metres per day. These rates are up to 20 times faster than the highest rate of ice sheet retreat that has so far been measured in Antarctica from satellites. </p>
<p>The highest rates of ice sheet retreat occurred across the flattest areas of the ice sheet’s bed. In flat-bedded areas, only a relatively small amount of melting, of around half a metre per day, is required to instigate a pulse of rapid retreat. Ice sheets in these regions are very lightly attached to their beds and therefore require only minimal amounts of melting to become fully buoyant, which can result in almost instantaneous retreat.</p>
<p>However, rapid “buoyancy-driven” retreat such as this is probably only sustained over short periods of time – from days to months – before a change in the ice sheet bed or ice surface slope farther inland puts the brakes on retreat. This demonstrates how nonlinear, or “pulsed”, the nature of ice sheet retreat was in the past. </p>
<p>This will likely also be the case in the future.</p>
<h2>A warning from the past</h2>
<p>Our findings reveal how quickly ice sheets are capable of retreating during periods of climate warming. We suggest that pulses of very rapid retreat, from tens to hundreds of metres per day, could take place across flat-bedded parts of the Antarctic Ice Sheet even under <a href="https://tc.copernicus.org/articles/13/2633/2019/">current rates of melting</a>. </p>
<p>This has implications for the vast and potentially unstable <a href="https://thwaitesglacier.org/about/facts">Thwaites Glacier</a> of West Antarctica. Since scientists began observing ice sheet changes via satellites, Thwaites Glacier has experienced <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014GL060140">considerable retreat</a> and is now only 4km away from a flat area of its bed. Thwaites Glacier could therefore suffer pulses of rapid retreat in the near future.</p>
<p>Ice losses resulting from retreat across this flat region could accelerate the rate at which ice in the rest of the Thwaites drainage basin collapses into the ocean. The Thwaites drainage basin contains enough ice to <a href="https://thwaitesglacier.org/about/facts">raise global sea levels by approximately 65cm</a>.</p>
<figure class="align-center ">
<img alt="The Fimbul Ice Shelf in East Antarctica." src="https://images.theconversation.com/files/519513/original/file-20230405-26-wcune3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519513/original/file-20230405-26-wcune3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519513/original/file-20230405-26-wcune3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519513/original/file-20230405-26-wcune3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519513/original/file-20230405-26-wcune3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519513/original/file-20230405-26-wcune3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519513/original/file-20230405-26-wcune3.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 Fimbul Ice Shelf in East Antarctica.</span>
<span class="attribution"><span class="source">Christine Batchelor</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our results shed new light on how ice sheets interact with their beds over different timescales. <a href="https://www.sciencedirect.com/science/article/pii/S092181811630491X">High rates of retreat</a> can occur over decades to centuries where the bed of an ice sheet deepens inland. But we found that ice sheets on flat regions are most vulnerable to extremely rapid retreat over much shorter timescales. </p>
<p>Together with data about the shape of ice sheet beds, incorporating this short-term mechanism of retreat into computer simulations will be critical for accurately predicting rates of ice sheet change and sea-level rise in the future.</p><img src="https://counter.theconversation.com/content/203277/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frazer Christie receives funding from the Prince Albert II of Monaco Foundation. </span></em></p><p class="fine-print"><em><span>Christine Batchelor 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>Seafloor landforms reveal that ice sheets can collapse at 600 metres per day.Christine Batchelor, Lecturer in Physical Geography, Newcastle UniversityFrazer Christie, Postdoctoral Research Associate, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1956932022-12-15T15:56:27Z2022-12-15T15:56:27ZGlaciers have existed on Earth for at least 60 million years – far longer than previously thought<figure><img src="https://images.theconversation.com/files/500682/original/file-20221213-1814-xh303t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Transantarctic Mountains peaks are some of the only parts of the continent not buried beneath ice.</span> <span class="attribution"><span class="source">Matt Makes Photos / shutterstock</span></span></figcaption></figure><p>Glaciers have been present somewhere on Earth for at least 60 million years, a period stretching back almost to the time of the dinosaurs. That’s the key finding of our <a href="https://www.nature.com/articles/s41467-022-33310-z">new research</a>, which pushes the date when the planet was last glacier-free back by at least 26 million years.</p>
<p>It may not feel like it due to profound recent warming, but Earth is currently in an “icehouse phase” – at least, relative to its long-term geological history. Even after a century of global warming and many glaciers shrinking or disappearing, conditions are still cold enough to support permanent ice sheets at both poles and more than 200,000 glaciers at high and low elevations and latitudes across the planet. This has not always been the case. </p>
<p>In the geological past Earth was much warmer and glaciers were almost certainly absent even from the very highest and coldest mountains. This is perhaps best demonstrated by the Late Cretaceous period (some 100 million to 66 million years ago), when dinosaurs roamed much of the planet and the climate was up to 20°C warmer than present. Then, the sort of “sub-tropical” forests you might find today in Mexico or India covered <a href="https://www.imperial.ac.uk/news/196516/traces-ancient-rainforest-antarctica-point-warmer/">most of Antarctica</a>.</p>
<p>As the climate cooled over the past 66 million years, Earth was pushed from a “greenhouse” into an “icehouse”, triggering ice ages and the growth of glaciers. The most dramatic cooling happened around 34 million years ago, when Antarctica first developed the ice sheets which now cover most of the continent in up to 4km of ice. However, it was less clear when the continent’s mountain glaciers first formed.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/500689/original/file-20221213-10619-5dike1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="map of Transantarctic Mountains" src="https://images.theconversation.com/files/500689/original/file-20221213-10619-5dike1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500689/original/file-20221213-10619-5dike1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=501&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500689/original/file-20221213-10619-5dike1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=501&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500689/original/file-20221213-10619-5dike1.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=501&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500689/original/file-20221213-10619-5dike1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=629&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500689/original/file-20221213-10619-5dike1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=629&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500689/original/file-20221213-10619-5dike1.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=629&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 Transantarctics are almost as long as the Rocky Mountains of North America, and just as high.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Transantarctic_mountains_highlighted.jpg">NASA</a></span>
</figcaption>
</figure>
<p>Our <a href="https://www.nature.com/articles/s41467-022-33310-z">new study</a> addresses this uncertainty by investigating when small glaciers first formed in the Transantarctic Mountains, a vast mountain chain that extends some 3,500km across the Antarctic continent. It is currently largely buried under the ice sheet but the areas which sit above the surface can be used to help understand when glaciers first appeared on the continent.</p>
<h2>The onset of Antarctic glaciation</h2>
<p>We used satellite images to map tens of thousands of glacial landforms, which can be valleys, cliffs, scratches in the rock or other features that have been formed at some point by glaciers. Given these are the world’s most remote and least hospitable mountains, mapping from satellite images in this way is far quicker than by visiting in person. But since the region is so big this still took more than a year of continuous work. </p>
<p>Our specific interest was in mapping glacial cirques, which are large glacially eroded bowl-shaped hollows (such as Cwm Idwal in North Wales, which was visited by Charles Darwin and helped convince him that the mountains of Britain <a href="https://www.geolsoc.org.uk/GeositesCwmIdwal">once held glaciers</a>). Using these cirques and our understanding of the climate conditions required for glaciers to form, we found that glaciers have likely existed in the highest mountains of Antarctica for at least the past 60 million years.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/500710/original/file-20221213-16138-f7sylx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="bowl-shaped valley with lake" src="https://images.theconversation.com/files/500710/original/file-20221213-16138-f7sylx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500710/original/file-20221213-16138-f7sylx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500710/original/file-20221213-16138-f7sylx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500710/original/file-20221213-16138-f7sylx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500710/original/file-20221213-16138-f7sylx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500710/original/file-20221213-16138-f7sylx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500710/original/file-20221213-16138-f7sylx.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">Cwm Idwal: Charles Darwin realised this Welsh valley must have been formed by glaciers.</span>
<span class="attribution"><span class="source">Iolo ap Gwynn / shutterstock</span></span>
</figcaption>
</figure>
<p>This is far earlier than reported by previous studies which suggest that mountain glaciers first developed just before 34 million years ago, immediately prior to the formation of the first ice sheet.</p>
<p>Our results instead indicate that Antarctica had glaciers <a href="https://www.nature.com/articles/nature01290">even when it was much warmer than now</a> and was mostly covered by dense sub-tropical forests. At the time, those were probably the only glaciers on Earth. </p>
<p>These high elevation mountain glaciers were likely swallowed up 34 million years ago by larger ice masses which eventually became a continent-wide ice sheet. It is likely that some mountain glaciers returned as the ice sheet retreated during the Miocene Climatic Optimum, a warm period some 15 million years ago, before a widespread switch to the sort of ice that continues to the present day.</p><img src="https://counter.theconversation.com/content/195693/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Scientists used satellites to map tens of thousands of glacial landforms in Antarctica’s highest mountains.Iestyn Barr, Reader in Physical Geography, Manchester Metropolitan UniversityBrice Rea, Professor, Geography, University of AberdeenKathryn Adamson, Senior Lecturer in Physical Geography, Manchester Metropolitan UniversityMatteo Spagnolo, Professor of Geography and the Environment, School of Geosciences, University of AberdeenLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1946422022-11-17T11:51:29Z2022-11-17T11:51:29ZAfrican mountains are feeling the heat of climate change<figure><img src="https://images.theconversation.com/files/495306/original/file-20221115-23-c6fqra.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mount Kenya</span> <span class="attribution"><span class="source">WanderingNomad / Getty IMages</span></span></figcaption></figure><p>Mountains are special places. They have distinctive climates that are generally cooler and wetter than surrounding lowlands, and they host plants, animals and landscapes that are uniquely found in these environments. However, mountains are under threat because of climate change, and this has an impact on every single property of mountains, including their climate, weathering and erosion processes, soils, ecosystems, water resources, geological hazards, regional economies, and cultural practices. </p>
<p>My <a href="https://peerj.com/articles/14253/">work</a> on the impacts of ongoing climate change in mountains highlights the sensitivity of mountain properties and processes to changes in temperature and precipitation – mainly expressed in mountains as snowfall. However, there is less understanding of mountain systems in Africa compared to other mountains globally. This article therefore focuses on mountain properties in Africa, why these are particularly sensitive to climate change, and why this is important.</p>
<h2>Ice and snow</h2>
<p>One key property of mountains worldwide is that they are often covered by snow and ice (glaciers). This reflects moist air and cold temperatures over mountain summits. Not only do snow and ice present unique habitats for plant and animal species, they also have a vital role in the regional climate systems of mountains. Snow and ice tend to be light in colour, so they reflect sunlight back out to space, keeping the land surface cold. This is called the <a href="https://scied.ucar.edu/learning-zone/how-climate-works/albedo-and-climate">albedo effect</a>. </p>
<p>However, if snowfall does not take place or the snow melts away, the mountain land surface remains dark. This means it absorbs rather than reflects the sun’s energy, making the surface warmer. This can cause more snowmelt, exposing more dark rocks, with more heating and melting. </p>
<p>The outcome of this process is that changing patterns of snowfall have big implications for mountain heat budgets. Mountains worldwide are already <a href="https://iccinet.org/statecryo22/">warming twice as fast</a> as the global average. This makes them particularly sensitive to climate change. </p>
<p>African mountains are not immune to climate change. Small glaciers still exist in three mountain massifs – Mount Kenya (Kenya), Kilimanjaro (Tanzania) and the Rwenzori mountains (Uganda) – but these are in <a href="https://wgms.ch/">rapid retreat</a>. They are also predicted to <a href="https://unesdoc.unesco.org/ark:/48223/pf0000383551">disappear entirely</a> by the middle of the century. Snowfall is also highly variable, such as over the <a href="https://earthobservatory.nasa.gov/images/88509/lesotho-sees-its-heaviest-snowfall-in-two-decades">Maloti-Drakensberg mountains</a> of southern Africa.</p>
<p>The full implications of this loss of ice and snow, and of climate change in African mountains more generally, have not been fully considered. Ice retreat in other deglacierising mountains worldwide leads to a substantial increase in hazards of different types, including rockfalls, landslides and debris flows. These hazards can also take place thousands of years after initial ice retreat. </p>
<p>This may mean that, even though the glaciers that exist in Africa today are very small, any resulting hazards could potentially be large and unpredictable in their timing and location. These are potentially future issues in African mountains. </p>
<p>Another important factor is how snow and ice melt across African mountains will affect their wider landscapes. Snow and ice often serve as water sources to surrounding communities, especially in locations that are water scarce, which includes East Africa. Water availability in the environment influences soils, ecosystems, river processes and the potential for flood and landslide hazards. </p>
<p>The presence of snow and ice therefore has wider environmental significance across mountain landscapes, and in ways that are not fully understood. </p>
<h2>Other important roles</h2>
<p>African mountains are also important for other reasons. For example, they host the Afromontane biogeographical region, a global <a href="https://www.cepf.net/our-work/biodiversity-hotspots/hotspots-defined">biodiversity hotspot</a> of endemic podocarp (conifer) forest species that extends as a corridor through upland areas of southern and eastern Africa. </p>
<p>Above the treeline, alpine pastures provide grazing land for herders, a key socioeconomic and cultural activity in remote mountains in Africa. </p>
<p>Summer and winter tourism – whether in South Africa or Morocco – is also linked closely to mountain landscapes, snow, water and the presence of endemic species. </p>
<p>All of these activities are under threat because of climate change. Mountain ecosystems are critically linked to temperature and precipitation conditions. Climate change may therefore pose problems for both the survival of keystone species and for overall biome integrity, especially where they are encroached by invasive species, agriculture and forestry. These changes also have secondary effects on ecosystem services, food, fuel and carbon storage. </p>
<p>Thus, mountains have a wide range of properties that are linked to climate, and a key question is how mountain systems as a whole will respond to climate change over future decades.</p>
<h2>Mountain communities</h2>
<p>Sustainable development of <a href="https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_CCP5.pdf">mountain communities</a>, where human activity responds to the changing nature of mountain systems, is a key strategy for minimising the impacts of climate change, both in mountains and in surrounding areas. </p>
<p>This can be done by monitoring and treating sources of hazard risk as a result of melting snow and ice, building resilient infrastructure and community resilience, and protecting mountains as sites of geological, ecological and cultural heritage. These actions can help limit climate change impacts on sensitive mountains in Africa and elsewhere.</p><img src="https://counter.theconversation.com/content/194642/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jasper Knight 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>Mountain systems are sensitive to climate change. Loss of snow and ice sets off effects which have wide ranging consequences.Jasper Knight, Professor of Physical Geography, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1929642022-11-14T10:52:04Z2022-11-14T10:52:04ZEarth’s cathedrals: Europe’s mountains are cultural heritage, not just natural heritage<figure><img src="https://images.theconversation.com/files/491056/original/file-20221021-12-zffs34.jpg?ixlib=rb-1.1.0&rect=0%2C23%2C3872%2C2562&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rocca Calascio is a mountaintop fortress in the province of L'Aquila in Italy. It bears witness to the long relationship between humanity and mountains, and how natural landscapes are also culture ones. </span> <span class="attribution"><span class="source">UNESCO</span>, <span class="license">Author provided</span></span></figcaption></figure><p>In 2019, alpinism was recognised by UNESCO as an <a href="https://ich.unesco.org/en/RL/alpinism-01471">intangible heritage of humanity</a> and “shared culture made up of knowledge of the high-mountain environment, the history of the practice and associated values, and specific skills”. However, alpinism is inextricably linked to mountains – places of extraordinary interest that need to be defended even more. The <a href="https://www.alpconv.org/en/">Alpine landscape protection initiatives</a> address issues of territorial planning, sustainable development, tourism, agriculture, and energy, but it is also essential to consider these topics through the lens of mountains’ historical and cultural values.</p>
<p>One session at the 10th International Congress of the <a href="https://aisuinternational.org/torino-2022/">Associazione Italiana di Storia Urbana (Italian Society of Urban History)</a> focused on this very theme. Titled <a href="https://aisuinternational.org/en/torino-2022-sessioni-2/">“The mountain landscape between eremitic contemplation, aesthetic attraction and sporting conquest”</a>, the 6.03 session explored current challenges and called for mountains to be protected not only as a natural heritage, but also as cultural heritage.</p>
<p>To achieve this ambitious goal, we must know and highlight the multiple meanings and cultural values of mountain landscapes. Only then can we implement integrated protection strategies similarly to what happens in the most well-known monumental sites.</p>
<h2>Bearing the brunt of climate change</h2>
<p>Due to melting ice and snow, mountains’ ecosystems are <a href="https://theconversation.com/climate-change-is-transforming-mountains-we-must-act-to-save-them-169886">particularly vulnerable to climate change</a>. They are also exposed to increasingly <a href="http://theconversation.com/dear-tourists-get-lost-when-social-contagion-creates-tourismophobia-130244">intensive visits</a>, which can damage them irreversibly if the values to be protected are not clearly identified. Their cultural relevance is often overlooked, however, or it’s exploited by tourism promotion and distorted by folklorisation phenomena.</p>
<p>Reflection on natural and cultural heritage should not be limited to sites of exceptional universal value; it must recognise mountain territories as places to be preserved not only for their environmental characteristics, but also for their historical and cultural values.</p>
<p>In the last 50 years, many alpine environments have significantly changed in appearance and in a few years’ time, several glaciers could be <a href="https://theconversation.com/listening-to-the-song-of-melting-glaciers-191041">gone for good</a>. This is not only a serious environmental problem, but an irreparable cultural loss. Glaciers are indeed archives of valuable information for science, as well as fading <a href="https://theconversation.com/climate-change-must-be-a-catalyst-for-reform-of-the-world-heritage-system-191798">historical landscapes</a>.</p>
<p>From the 17th until the 19th century, upper-class young European men were expected to take on a ‘<a href="https://www.amazon.fr/Evolution-Grand-Tour-Anglo-Italian-Renaissance/dp/0714644749">Grand Tour</a>’ through Europe up to Italy. 'Eternal snows’ required the travellers to make at least one stop in the Alps on their adventurous and difficult journeys to get there (William Windham 1741; Pierre Martel 1742).</p>
<p>Hannibal <a href="https://www.britannica.com/biography/Hannibal-Carthaginian-general-247-183-BC/The-Alpine-crossing">crossed the Alps in 218 BC</a>, and left traces in the descriptions of historians. Constructed over the centuries, structures such as huts and shelters, roads, pilgrim hospices, and churches have shown how deep our relationship has been with mountain territories. During the First and Second World Wars, more notable material testimonies were left behind, including fortifications, tunnels, trenches, shelters, barracks and places of the Resistance.</p>
<figure class="align-center ">
<img alt="Hermitage of San Bartolomeo in Legio, Italy." src="https://images.theconversation.com/files/491057/original/file-20221021-3368-z42jq1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491057/original/file-20221021-3368-z42jq1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491057/original/file-20221021-3368-z42jq1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491057/original/file-20221021-3368-z42jq1.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491057/original/file-20221021-3368-z42jq1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491057/original/file-20221021-3368-z42jq1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491057/original/file-20221021-3368-z42jq1.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">Hermitage of San Bartolomeo in Legio, Italy.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>These artefacts are part of a widespread cultural heritage, the knowledge of which is essential to recognise if we are to preserve them. In fact, such sites, often abandoned, are hardly perceived as monumental. What is needed is for them to be seen in a broad perspective that considers them a “system” to be protected for their historical, aesthetic, landscape, identity values, not just as individual artefacts.</p>
<h2>The cultural pull of mountain landscapes</h2>
<p>The spiritual and intellectual attraction to the mountains is testified by hermits, artists and scientists well before the age of mountaineering, which officially starts with the <a href="https://www.vox.com/2015/8/8/9119081/mont-blanc-first-ascent">first ascent of Mont Blanc in 1786</a>. However, expeditions to the mountains began much earlier for scientific and cultural reasons (<a href="https://www.cambridge.org/core/books/abs/heights-of-reflection/from-meadows-to-mountaintops-albrecht-von-hallers-die-alpen/83DCD7EA3DF5AAA440F81421FB472303">Albrecht von Haller 1729</a>; <a href="https://www.edition-originale.com/fr/livres-anciens-1455-1820/philosophie/rousseau-lettres-ecrites-de-la-montagne-1764-47448">Jean-Jacques Rousseau 1764</a>; <a href="https://www.editionsladecouverte.fr/premieres_ascensions_au_mont_blanc_1774_1787-9782707147035">Horace Benedict de Saussure 1774</a>).</p>
<p>Since then, scholars and travellers have turned their interest not only to monuments of antiquity but also toward the wonders of nature, specifically to the alpine glaciers. The first material evidence of Alpine visits was the <a href="https://www.eaae.be/wp-content/uploads/2019/12/EAAE-2019-Conservation-Consumption.pdf">“Temple de la Nature”</a>, a refuge built in 1795 in Montenvers to observe the <a href="https://www.britannica.com/place/Mer-de-Glace">Mer de Glace</a>, still visible today among the hotels built later.</p>
<p>In the same years, Orazio Delfico’s ascent of the Gran Sasso d'Italia in 1794 was considered the first ascent of the highest peak of the Apennines. However, as early as 1573, Francesco de Marchi – an architect following Margaret of Austria – reached the mountain summit and published the chronicle of the ascension in his <a href="http://www.lagagransasso.it/gs/de_marchi.htm">“Treaty of Military Architecture”</a>. Other writers and scientists to have scaled mountains include Francesco Petrarca on Mont Ventoux in Provence (1336), Leon Battista Alberti on Monte Velino in Abruzzo (mid-15th century), Leonardo da Vinci on Monte Rosa and perhaps also in Abruzzo (late 15th century to early 16th Century).</p>
<h2>“Cathedrals of the Earth”</h2>
<p>In the 19th century, the English writer John Ruskin celebrated mountains by describing them as “<a href="https://issuu.com/dida-unifi/docs/volume_1/20">Cathedrals of the Earth</a>”. Following up on Lord Byron’s depiction of them as [“Palaces of Nature”], such an expression captured at once the landscapes’ magnificence and called upon visitors to respect them as sacred. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/494203/original/file-20221108-18-kzijh6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/494203/original/file-20221108-18-kzijh6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/494203/original/file-20221108-18-kzijh6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=356&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494203/original/file-20221108-18-kzijh6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=356&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494203/original/file-20221108-18-kzijh6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=356&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494203/original/file-20221108-18-kzijh6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=448&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494203/original/file-20221108-18-kzijh6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=448&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494203/original/file-20221108-18-kzijh6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=448&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">John Ruskin’s sketch of the Aiguille Blaitière, circa 1856.</span>
<span class="attribution"><a class="source" href="https://fr.m.wikipedia.org/wiki/Fichier:The_Aiguille_Blaitiere.jpg">Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>All this demonstrates a very close relationship between the protection of cultural and mountain heritage. Thus, mountains’ cultural values precede the mountaineering interest that developed with the birth of the Alpine Clubs first in the United Kingdom (1857), then in Austria (1862), Italy (1863) and France (1874). Since then, mountains have increasingly become synonymous with competitive challenges, sometimes with alienating outcomes.</p>
<p>Founded by John Muir in 1892 in San Francisco, the <a href="https://www.sierraclub.org/">Sierra Club</a> was, by contrast, one of the first organisations for the conservation of the mountain landscape. Well ahead of his time, Muir held up mountain parks and reserves as a necessity for human well-being and ‘sources of life’.</p>
<blockquote>
<p>“It is by far the grandest of all of His special temples of Nature I was ever permitted to enter. It must be the sanctum sanctorum of the Sierras.” (John Muir, Letters to a Friend. Written to Mrs. Ezra S. Carr (1866-1879) in J. Muir, Andare in montagna è tornare a casa. Scritti sulla natura selvaggia (trad. it. Caterina Bernardini) </p>
</blockquote>
<p>Any reflection about the <a href="https://whc.unesco.org/en/next50/">future of heritage</a> must consider the close interaction between tangible and intangible heritage (otherwise there is the risk of neglecting the material assets connected to intangible values), and then extend it to the safeguard of the planet as a World Heritage. In this sense, it is necessary to integrate the defence of territory and environment with the identification of its multiple cultural values.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=305&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=305&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=305&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=383&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=383&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=383&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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<p><em><a href="https://whc.unesco.org/en/next50/">50th anniversary of the World Heritage Convention</a> (16 November 2022): World Heritage as a source of resilience, humanity and innovation.</em></p><img src="https://counter.theconversation.com/content/192964/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Carla Bartolomucci ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Often thought of as eternal, mountains are vulnerable to climate change and tourism. To protect them, they should be recognised for their cultural values, not just their natural characteristics.Carla Bartolomucci, Associate professor of architectural conservation, University of L'AquilaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1891972022-10-18T16:37:55Z2022-10-18T16:37:55ZGlaciers in the Alps are melting faster than ever – and 2022 was their worst summer yet<figure><img src="https://images.theconversation.com/files/489197/original/file-20221011-25-oj2kz1.jpg?ixlib=rb-1.1.0&rect=1834%2C0%2C9111%2C5320&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Aletsch Glacier in Switzerland is the largest in the Alps. A century ago it was several kilometres longer and several hundred metres thicker. </span> <span class="attribution"><span class="source">Alberto Garcia Guillen / shutterstock</span></span></figcaption></figure><p>Finally, after what was arguably the worst summer on record for glaciers, snow has begun to fall in the European Alps. It is much needed. Over the 19 years that I have visited and studied the glaciers in Switzerland, I have not seen a summer like 2022. The scale of change is staggering. </p>
<p>Glaciologists like me used to use the word “extreme” to describe annual ice loss of around 2% of a glacier’s overall volume. This year Switzerland’s glaciers have lost an average of <a href="https://scnat.ch/en/uuid/i/2e076759-0234-567e-9bfb-2cdfebd6ff34-Worse_than_2003_Swiss_glaciers_are_melting_more_than_ever_before">6.2% of their ice</a> – extreme indeed. </p>
<p>The new flurries of snow will form a protective blanket to shield and reflect 90% of the sun’s radiation back into the atmosphere and limits the warming and melting of the ice beneath. When snow falls over the winter, and then subsequently doesn’t melt over the summer, it adds to the mass of a glacier. Over a few similar years, gravity would take over and glaciers would start to advance downhill. </p>
<p>However over the past century, that has not been the case. The protective layers of snow have not been thick enough to offset the warming summer temperatures and on average <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf">glaciers around the world have been wasting away</a> since the end of the little ice age in the mid-late 1800s.</p>
<h2>Saharan sand and a huge heatwave</h2>
<p>Back to this summer. Across the Alps, the preceding winter had very limited snowfall and therefore glaciers were not well insulated against the forthcoming summer melt season. </p>
<p>Spring was particularly harsh as natural atmospheric weather patterns carried <a href="https://www.severe-weather.eu/global-weather/saharan-dust-cloud-europe-march-2022-forecast-mk/">Saharan dust</a> to Europe and blanketed the Alpine landscape. Since dust absorbs more solar energy than snow (which is white and therefore more reflective), the now orange-tinted snow melted faster than ever. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1358399804670418948"}"></div></p>
<p>Then a major heatwave saw temperature records smashed across Europe, with parts of the UK <a href="https://theconversation.com/heatwave-britain-hits-40-3-c-heres-how-scientists-know-when-a-temperature-record-has-been-broken-187235">reaching 40°C</a> for the first time. The Alps were not spared. For instance Zermatt, a famous car-free Swiss village in the shadow of the Matterhorn, recorded temperatures up to 33°C despite being 1,620 meters above sea level. </p>
<p>Glaciers in particular took a beating. By July, the Alps looked like they normally look in September: snow free, with snow and ice-fed rivers flowing at their peak. This was not normal. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/489161/original/file-20221011-17-e3h6bi.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Satellite image of glaciers" src="https://images.theconversation.com/files/489161/original/file-20221011-17-e3h6bi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489161/original/file-20221011-17-e3h6bi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489161/original/file-20221011-17-e3h6bi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489161/original/file-20221011-17-e3h6bi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489161/original/file-20221011-17-e3h6bi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489161/original/file-20221011-17-e3h6bi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489161/original/file-20221011-17-e3h6bi.png?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">Glaciers near Zermatt in July 2021 – a ‘normal’ year.</span>
<span class="attribution"><a class="source" href="https://sentinels.copernicus.eu/web/sentinel/home">Copernicus Sentinel / European Space Agency - ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/489170/original/file-20221011-19-qz7rpm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Satellite image of much smaller glaciers" src="https://images.theconversation.com/files/489170/original/file-20221011-19-qz7rpm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489170/original/file-20221011-19-qz7rpm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489170/original/file-20221011-19-qz7rpm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489170/original/file-20221011-19-qz7rpm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489170/original/file-20221011-19-qz7rpm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489170/original/file-20221011-19-qz7rpm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489170/original/file-20221011-19-qz7rpm.png?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">…and the same glaciers in July 2022.</span>
<span class="attribution"><a class="source" href="https://sentinels.copernicus.eu/web/sentinel/home">Copernicus Sentinel / European Space Agency - ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>The last time glaciers had an extreme melt season was in 2003 when, again, temperatures were very high across Europe, and a heatwave killed at least 30,000 people (more than 14,000 in France alone). That calendar year, <a href="https://twitter.com/glamos_ch/status/1575011474870661125">3.8% of glacier ice</a> melted across Switzerland. </p>
<p>This year, for the first time ever, Zermatt closed its summer skiing. Guides stopped leading high mountain expeditions as permafrost – the frozen ground that binds rocks together – was thawing and causing almost constant rockfalls. <a href="https://explorersweb.com/mont-blanc-climbing-closed">Mont Blanc was closed</a>.</p>
<h2>50 years of data</h2>
<p>We are able to put this in historical context thanks in part to work by the charitable organisation <a href="https://alpineglacierproject.org/">Alpine Glacier Project</a> which was established in 1972 and, along with the <a href="https://www.salford.ac.uk/study-environment">University of Salford</a> where I work, has led scientific expeditions to glaciers near Zermatt every summer for 50 years. </p>
<p>Scores of students have helped to observe the effect of our warming climate through chemically monitoring changes in meltwater, topographically surveying the landscape and by taking photos from the same position over the years. Over the project’s five decades, Gorner Glacier and Findel Glacier have retreated 1,385 metres and 1,655 metres respectively. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/489428/original/file-20221012-18-3wbmt0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three photos of mountain range with progressively smaller glacier" src="https://images.theconversation.com/files/489428/original/file-20221012-18-3wbmt0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489428/original/file-20221012-18-3wbmt0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=181&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489428/original/file-20221012-18-3wbmt0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=181&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489428/original/file-20221012-18-3wbmt0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=181&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489428/original/file-20221012-18-3wbmt0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=228&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489428/original/file-20221012-18-3wbmt0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=228&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489428/original/file-20221012-18-3wbmt0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=228&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Same view of the Gorner Glacier near Zermatt in 1920, 1972 and 2022.</span>
<span class="attribution"><span class="source">Alpine Glacier Project, David Collins, Neil Entwistle</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/489404/original/file-20221012-20-1dn0nj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two photos of mountain valley with larger and smaller glacier" src="https://images.theconversation.com/files/489404/original/file-20221012-20-1dn0nj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489404/original/file-20221012-20-1dn0nj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489404/original/file-20221012-20-1dn0nj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489404/original/file-20221012-20-1dn0nj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489404/original/file-20221012-20-1dn0nj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489404/original/file-20221012-20-1dn0nj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489404/original/file-20221012-20-1dn0nj.png?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">Left: University of Salford students on a Alpine glacier visit in 2009 looking toward the tongue of the Gorner Glacier. Right the same view in 2022.</span>
<span class="attribution"><span class="source">Neil Entwistle</span></span>
</figcaption>
</figure>
<p>In Switzerland these glacial meltwaters are used for hydropower. In fact, water falling on <a href="https://www.sciencedirect.com/science/article/abs/pii/S0960148118309017">93% of Switzerland</a> ultimately passes through at least one electric power plant before even leaving the country. So one consequence is that melting glaciers help to compensate for low rainfall in times of drought, filling reservoirs to supply the nations energy supply. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1575011474870661125"}"></div></p>
<p>You could argue that not all glaciers were equally affected by this summer’s catastrophic retreat and ice loss. In part, this is true. The extent to which a glacier has melted does depend on the altitude at which it is located, how steep the glacier tongue is, and how heavily it is covered with debris. There may too be localised climate factors. </p>
<p>However, research just <a href="https://wgms.ch/latest-glacier-mass-balance-data/">published</a> has shown that Austrian glaciers have also lost more glacial ice in 2022 than they have in 70 years of observations and therefore it is quite clear that severe melt has been the norm in 2022.</p>
<p>Visiting and viewing the geography of high mountain environments is a breathtaking experience, but my fear is that the continued ice melt and extreme temperatures seen this year are not an anomaly. Many more glaciers could be lost entirely within a generation.</p><img src="https://counter.theconversation.com/content/189197/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Neil Entwistle receives research funding from NERC, and The Environment Agency. He is affiliated with Manchester Geographical Society, Royal Geographical Society, and the Alpine Glacier Project.</span></em></p>Switzerland’s glaciers just lost 6% of their ice in a single year.Neil Entwistle, Professor of River Science and Climate Resilience, University of SalfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1917982022-10-16T15:29:44Z2022-10-16T15:29:44ZClimate change must be a catalyst for reform of the World Heritage system<figure><img src="https://images.theconversation.com/files/489563/original/file-20221013-11-omsint.jpg?ixlib=rb-1.1.0&rect=0%2C13%2C2204%2C1352&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Switzerland's Great Aletsch Glacier is 23km long and located in the World Heritage site Swiss Alps Jungfrau-Aletsch. It leads the list of glaciers in the European Alps in terms of length and size, yet since the mid-19th century, it has lost more than 25% of its volume.</span> <span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/b/be/Great_Aletsch_Glacier.jpg">Jo in Riederalp/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Over the last few years, many parts of the world have been devastated by <a href="https://www.carbonbrief.org/mapped-how-climate-change-affects-extreme-weather-around-the-world/">extreme droughts, floods, wild fires and heatwaves linked to climate change</a>. But climate change is not only influencing our weather: it also poses an existential threat to the outstanding universal value (OUV) of many of the world’s most precious sites on UNESCO’s <a href="https://whc.unesco.org/en/list/">World Heritage List</a>, and potentially to the World Heritage system itself.</p>
<p>This year is the 50th anniversary of the <a href="https://whc.unesco.org/en/convention/">World Heritage Convention</a>, one of the most successful international conventions. It was adopted in 1972 to protect globally significant heritage places as a common heritage of humankind. Renowned World Heritage sites include the Taj Mahal, the Great Wall of China, Yellowstone National Park and the Galápagos. The convention has been signed by 194 countries (known as states parties). More than 1,150 sites in 167 countries have been inscribed on the World Heritage List for their cultural and/or natural values. On average, around 25 more sites are added to the list at each of the annual meetings of the World Heritage Committee, even as existing sites come under threat from climate change.</p>
<figure class="align-center ">
<img alt="The increasing number of World Heritage sites and their increasing exposure to greenhouse gases causing climate change" src="https://images.theconversation.com/files/487752/original/file-20221003-16-qm218l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487752/original/file-20221003-16-qm218l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=304&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487752/original/file-20221003-16-qm218l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=304&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487752/original/file-20221003-16-qm218l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=304&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487752/original/file-20221003-16-qm218l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=382&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487752/original/file-20221003-16-qm218l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=382&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487752/original/file-20221003-16-qm218l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=382&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The rise is the number of World Heritage sites and their increasing exposure to greenhouse gases responsible for climate change.</span>
<span class="attribution"><span class="source">Greg Terrill/UNESCO</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>Climate change is now the most significant threat to many World Heritage sites, especially those inscribed for their natural values. Short- and long-term climate-related impacts are increasing. For example, by 2100 and depending on the emissions scenario used, complete glacier extinction is predicted for <a href="https://doi.org/10.1029/2018EF001139">8 to 21 World Heritage sites</a>, within which glaciers are an attribute of their universal value. The number of <a href="https://doi.org/10.1038/s41558-022-01280-1">African coastal heritage sites at risk</a> from a 100-year extreme flooding and coastal-erosion event, including the <a href="https://whc.unesco.org/en/list/599/">Stone Town of Zanzibar</a> and <a href="https://whc.unesco.org/en/list/599/">Mozambique Island</a>, is projected to more than triple by 2050 under a moderate emissions scenario.</p>
<p>Impacts are cumulative and some will persist for centuries after the world achieves net-zero emissions. Climate change is a threat multiplier, exacerbating existing threats, impacting sites in increasingly complex ways, and demanding further resources for management and adaptation. Food insecurity, social stresses and the displacement of populations as a consequence of climate change will further increase pressures on World Heritage sites.</p>
<p>The concept of outstanding universal value is fundamental to the World Heritage Convention and its processes. OUV has generally been interpreted assuming that the environment is largely stationary, something that climate change has proved incorrect. It will ultimately be impossible to maintain the outstanding universal value for which many sites were inscribed, even if effective global and local mitigation strategies and local adaptation strategies are implemented.</p>
<p>[<em>Nearly 80,000 readers look to The Conversation France’s newsletter for expert insights into the world’s most pressing issues</em>. <a href="https://theconversation.com/fr/newsletters/la-newsletter-quotidienne-5?utm_source=inline-70ksignup">Sign up now</a>]</p>
<p>In Venice, the effectiveness of massive retractable barriers constructed at the entrance to the lagoon will be tested by the <a href="https://doi.org/10.5194/nhess-21-2643-2021">projected sea-level rise</a> of anywhere from 17cm to 120cm by 2100 that will bring increasingly frequent, longer-lasting and potentially permanent flooding. A <a href="https://gbrrestoration.org/">restoration and adaptation program</a> is attempting to develop a suite of safe, acceptable interventions to help the <a href="https://whc.unesco.org/en/list/154/">Great Barrier Reef</a> resist, adapt to, and recover from the impacts of climate change. However, it will be challenging to operationalise interventions at scale across this large World Heritage Area.</p>
<figure class="align-center ">
<img alt="Venice flooding, 2010" src="https://images.theconversation.com/files/489426/original/file-20221012-14-i7ulul.jpg?ixlib=rb-1.1.0&rect=0%2C9%2C2048%2C1140&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489426/original/file-20221012-14-i7ulul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489426/original/file-20221012-14-i7ulul.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489426/original/file-20221012-14-i7ulul.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489426/original/file-20221012-14-i7ulul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489426/original/file-20221012-14-i7ulul.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489426/original/file-20221012-14-i7ulul.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">
<figcaption>
<span class="caption">Flooding has long been a threat in Venice, Italy, but with a projected sea-level rise of anywhere from 17cm to 120cm by 2100, higher water levels will be more frequent, longer-lasting and potentially permanent.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/23748404@N00/5265451716">A. Currell/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Substantive reforms are necessary for the World Heritage system to address these challenges. Although amending international conventions is notoriously difficult, the convention is a treaty where many important matters are dealt with in subsidiary documents, especially its <a href="https://whc.unesco.org/en/guidelines/">operational guidelines</a>, which are much easier to change than the convention, if state parties so wish.</p>
<p>An open-ended working group is working to finalise a <a href="https://whc.unesco.org/archive/2021/whc21-23GA-inf11-en.pdf">policy document on climate action for World Heritage</a> and to develop an implementation plan. The document outlines high-level directives but says little about the operational reforms required to address the scale and complexity of the challenges. Meaningful operational reforms are likely to be highly contested because of the differing priorities of various states parties. For example, African nations are very concerned about the <a href="https://whc.unesco.org/en/news/2441">under-representation of African sites</a> on the World Heritage List and the perceived over-representation of African sites on the list of World Heritage in Danger.</p>
<p>In 2021, the Australian Academy of Science bought together 18 experts – in climate science, climate vulnerability assessment, IPCC processes, cultural, natural and Indigenous heritage, outlook reporting, site management, World Heritage system processes, environmental law, international law and diplomacy – in a roundtable on reforms to the convention to address the consequences of climate change. Their <a href="https://www.science.org.au/files/userfiles/support/reports-and-plans/2022/climate-change-world-heritage-roundtable-report.pdf">ideas for change</a> focused on three key areas:</p>
<ul>
<li><p>identification of climate-related threats to World Heritage sites;</p></li>
<li><p>the processes for state party reporting to the World Heritage Committee;</p></li>
<li><p>responses to climate impacts to outstanding universal value.</p></li>
</ul>
<h2>Identification of climate-related threats</h2>
<p>Introducing a requirement for World Heritage nominations to include a standardised vulnerability assessment could provide a baseline against which climate-related impacts to its potential OUV could be monitored. Currently there is no agreed standard: several methods have been applied to <a href="https://doi.org/10.5070/P536146384">individual sites</a> and a <a href="https://doi.org/10.1016/j.envc.2022.100538">thematic approach</a> has also been used, assessing comparable sites or groups of sites facing similar risks. Clear guidelines around the requirements for such assessments need to be discussed and developed so that assessments are systematic, useful and comparable.</p>
<p>The World Heritage Committee responds to threats to outstanding universal value through complex and resource-hungry reporting processes – these include state-of-conservation reporting, reactive monitoring and a six-year cycle of periodic reporting based on geography. These processes are already under strain due to the large number of sites in the reporting cycle. In 2021, less than 20% of the state-of conservation reports were discussed by the committee. Given the anticipated increase in the number and severity of threats as a result of climate change, the reporting processes need reconsideration. Such change cannot take place without considerable discussion.</p>
<h2>Responding to climate impacts</h2>
<p>As climate change accelerates, the outstanding universal value of some World Heritage sites will be severely or permanently impacted. In others, the changes may be milder. Limits of acceptable change could be developed for each property to identify the amount or nature of change that each property’s attributes can sustain without irretrievable loss of OUV. Accepting that change is inevitable, improved methods are needed to assess significant and minor changes to each site’s statement of OUV as well as clearer guidelines and thresholds for including a site on the <a href="https://whc.unesco.org/en/danger/">List of World Heritage in Danger</a> or delisting it.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/489570/original/file-20221013-18-adrgad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489570/original/file-20221013-18-adrgad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489570/original/file-20221013-18-adrgad.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489570/original/file-20221013-18-adrgad.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489570/original/file-20221013-18-adrgad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489570/original/file-20221013-18-adrgad.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489570/original/file-20221013-18-adrgad.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">Arlington Reef, located in Queensland, is part of Australia’s Great Barrier Reef. Developing a set of safe interventions to help this fragile World Heritage site minimise and adapt to the impacts of climate change is essential.</span>
<span class="attribution"><span class="source">Luka Peternel/Wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>These reforms could result in more systematic and comparable evidence for climate impacts as a basis for realistic adaptation strategies and greater transparency and objectivity in decision-making by the World Heritage Committee.</p>
<p>Substantive reform of the operational guidelines would be a fitting project to commence in 2022, the 50th anniversary of the convention. We hope this article will stimulate widespread discussion about these matters, which are existential to the future of the Convention and its capacity to protect the world’s most precious heritage places in the face of climate change.</p>
<p><em>The authors gratefully acknowledge Greg Terrill for his ideas and comments and for Figure 1.</em></p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=305&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=305&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=305&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=383&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=383&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485372/original/file-20220919-20-pguqfq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=383&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><a href="https://whc.unesco.org/en/next50/">50th anniversary of the World Heritage Convention</a> (16 November 2022): World Heritage as a source of resilience, humanity and innovation.</em></p><img src="https://counter.theconversation.com/content/191798/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Les auteurs ne travaillent pas, ne conseillent pas, ne possèdent pas de parts, ne reçoivent pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'ont déclaré aucune autre affiliation que leur organisme de recherche.</span></em></p>Rising temperatures and extreme weather pose an existential threat to many UNESCO World Heritage sites, but widespread discussion is needed for meaningful change.Helene Marsh, Emeritus Professor, Environmental Science, James Cook UniversityAnita Smith, Associate professor, Archaeology and Heritage, La Trobe UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1910412022-09-28T18:33:59Z2022-09-28T18:33:59ZListening to the song of melting glaciers<figure><img src="https://images.theconversation.com/files/485694/original/file-20220920-13677-ppvp23.jpg?ixlib=rb-1.1.0&rect=500%2C19%2C3466%2C2715&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A look into the heart of the glacier</span> <span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p><em>August 22, 2022. Kongsvegen glacier, 20 km west of Ny Ålesund, Svalbard archipelago, Norway.</em></p>
<hr>
<p>This is it, we have reached the bottom of the glacier. It is 327m under our feet. After drilling into the ice for six hours, our hot-water jet blasts into the sediment. The hose that connects it to the surface stops rolling and Thomas Schuler, the project leader, confirms that the base has been reached. </p>
<p>I get off the helicopter and Coline Bouchayer, a PhD researcher overseeing the project, tells me the good news. We let out a sigh of relief – John Hult, the project engineer, and Svein Oland, a mechanic from the Norwegian Polar Institute, are particularly content. We had tried to carry out the same operation last spring, but the -30°C temperatures froze the water in the drilling system, making it impossible to continue. This time, the engines that are still running bring a smell of diesel to the frozen lands around us. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/485688/original/file-20220920-3487-e4vmh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/485688/original/file-20220920-3487-e4vmh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485688/original/file-20220920-3487-e4vmh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=357&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485688/original/file-20220920-3487-e4vmh3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=357&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485688/original/file-20220920-3487-e4vmh3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=357&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485688/original/file-20220920-3487-e4vmh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=449&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485688/original/file-20220920-3487-e4vmh3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=449&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485688/original/file-20220920-3487-e4vmh3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=449&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Kongsvegen, the Arctic glacier in Svalbard where we carried out our research. To find out what lies hundreds of metres below, we drilled down to the sediments beneath the glacier (see green stars). There, we installed a ploughmeter to measure the forces at the base of the glacier, and several seismometers to ‘listen’ to the vibrations of the glacier. We also put up seismometers at various locations (yellow dots) on the surface of the glacier.</span>
<span class="attribution"><span class="source">T.V. Schuler</span></span>
</figcaption>
</figure>
<p>Our goal here is not to reconstruct <a href="https://www.ice-memory.org/">past climates</a> by extracting ice cores like missions in Antarctica or Greenland. Instead, it is to explore what happens hundreds of metres below the surface, where the glacier rests on its bed of rocks and sediment. This is where their stability is at stake, as liquid water from the surface seeps in and acts as a lubricant. </p>
<p>Rapidly rising temperatures brought on by climate change are set to melt glaciers and trigger instabilities, as predicted by the <a href="https://www.ipcc.ch/srocc/">Intergovernmmental Panel on Climate Change (IPCC)</a>. <a href="https://climateactiontracker.org/global/temperatures/">Current policies</a> are projected to result in about 2.7°C warming above pre-industrial levels by 2100, way above the 1.5°C maximum recommended limit by the <a href="https://climate.ec.europa.eu/eu-action/international-action-climate-change/climate-negotiations/paris-agreement_en">Paris agreement</a>. Such differences can be drastic for glaciers. These ice dragons, which look as if they were asleep, can wake up a little too suddenly, as shown by the recent <a href="https://www.reuters.com/business/environment/glacier-collapses-italian-alps-least-6-reported-dead-2022-07-03/">collapse of glaciers in the Italian Alps</a>. </p>
<figure class="align-center ">
<img alt="Iceberg graph" src="https://images.theconversation.com/files/486762/original/file-20220927-22-fjigqy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486762/original/file-20220927-22-fjigqy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486762/original/file-20220927-22-fjigqy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486762/original/file-20220927-22-fjigqy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486762/original/file-20220927-22-fjigqy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486762/original/file-20220927-22-fjigqy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486762/original/file-20220927-22-fjigqy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Glaciers move thanks to the presence of liquid water at the ice-bed interface. Even the slightest movement creates a vibration that can be recorded by our seismometers.</span>
<span class="attribution"><span class="source">Ugo Nanni</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The movement of glaciers (from a few metres to several kilometres per year) is similar to that of a soft cheese on a sloping board: they sway over their entire height and creep under their own weight. The steeper and thicker they are (up to several kilometres), the faster they flow to lower altitudes. Thanks to the thin layer of water between the ice and its rocky bed, glaciers can double their speed between winter and summer. While most glaciers enjoy a stable seasonal cycle, some, including Kongsvegen, have seen their annual speed increase over the years. </p>
<p>This is known as a <em>glacial surge</em>. Since 2010, the speed of the upper part of Kongsvegen has increased from a few metres a year to more than 40 – a tenfold increase. For the time being, this only affects the upper part of the glacier, but we are seeing a progression from year to year toward the lower areas.</p>
<p>We believe that this dynamic could lead to a destabilisation of the glacier, and if this happens, this glacier, which is more than 15km long, 2km wide, and 300m thick, could plunge into the ocean and cause major damage to the entire fjord. And Kongsvegen is just one of thousands of cases across the world. To understand this, we melt our way downward and plunge our instruments into the unknown heart of the glacier.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/485902/original/file-20220921-10505-2g7jll.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/485902/original/file-20220921-10505-2g7jll.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485902/original/file-20220921-10505-2g7jll.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=303&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485902/original/file-20220921-10505-2g7jll.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=303&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485902/original/file-20220921-10505-2g7jll.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=303&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485902/original/file-20220921-10505-2g7jll.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=381&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485902/original/file-20220921-10505-2g7jll.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=381&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485902/original/file-20220921-10505-2g7jll.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=381&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 multiyear acceleration of Kongsvegen measured by Jack Kohler (Norwegian Polar Institute) and his team. It shows that the speed of the glacier has increased from a few metres year to more than 40 in the upper part of the glacier over the last decade. This acceleration is slowly spreading towards the front of the glacier. The background image shows that this acceleration often leads to the formation of crevasses and could lead to the destabilisation of the glacier. Yellow dots and green stars show the location of the instrument deployed on the glacier (Figure 1).</span>
</figcaption>
</figure>
<p>Our <a href="https://www.mn.uio.no/geo/english/research/projects/mammamia/">scientific mission</a> aims to listen to Kongsvegen and measure the forces that it exerts on its underlying rocky bed. If these forces are greater than what the bed can hold, then we start to have serious problems. </p>
<p>The slightest movement of a glacier generates a vibration that contains <a href="https://blogs.egu.eu/divisions/cr/2022/06/03/cryoseismology/">crucial information about its dynamics</a>. The <a href="https://soundcloud.com/ugonanni/the-song-of-arctic-glaciers">sound</a> of glaciers is primitive. It travels from your ears to your guts. You hear your desire of exploration as well as the impact of our society on our environment. It is difficult to say whether they are mourning, singing or laughing, but they are certainly not silent. This year, my friend Clovis Tisserand, a <a href="https://www.clovistisserand.fr/">sound designer</a>, came with me to record these voices from the Arctic. </p>
<p><br></p>
<p><audio preload="metadata" controls="controls" data-duration="3657" data-image="" data-title="The song of arctic glaciers, Ugo Nanni" data-size="58520960" data-source="Ugo Nanni" data-source-url="https://soundcloud.com/ugonanni/the-song-of-arctic-glaciers" data-license="CC BY" data-license-url="http://creativecommons.org/licenses/by/4.0/">
<source src="https://cdn.theconversation.com/audio/2605/geophones-2021-08-28-1-hour.mp3" type="audio/mpeg">
</audio>
<div class="audio-player-caption">
The song of arctic glaciers, Ugo Nanni.
<span class="attribution"><a class="source" rel="nofollow" href="https://soundcloud.com/ugonanni/the-song-of-arctic-glaciers">Ugo Nanni</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a><span class="download"><span>55,8 Mo</span> <a target="_blank" href="https://cdn.theconversation.com/audio/2605/geophones-2021-08-28-1-hour.mp3">(download)</a></span></span>
</div></p>
<p><br></p>
<p>My job is to analyse these sounds to understand how the glacier moves, how it reacts to surface melting, how its crevasses open and what is happening in its depths. To do this, we use <em>seismometers</em>, traditionally employed to study earthquakes. Since 2020, we have installed about 20 of these along the length of Kongsvegen and in its depths. With such a network, we can listen to the whole glacier, like a doctor with a stethoscope, and its secrets (as we recently did in the <a href="https://resolve.osug.fr/">French Alps</a>). On top of these seismometers, we have also installed a rather unusual instrument, a long 2m steel rod planted at a depth of 360m called a <em>ploughmeter</em> (Figure 1). </p>
<p>On this rod, John installed several <a href="https://dewesoft.com/daq/strain-gauge-applications">strain gauges</a> to measure the forces at the base of the glacier. The ploughmeter we installed this summer only transmitted its measurements for a few hours before going silent despite days spent by John trying to revive it. Fortunately for Coline, whose PhD is partly based on these measurements, the one installed in spring 2021 is still talking. Since that date, we have therefore been able to measure how the glacier vibrates, distorts itself and slides in response to changes in temperature and precipitation.</p>
<p>Collecting this data was time-consuming, costly, and subject to many uncertainties. It was made possible thanks to the support of numerous colleagues, the Norwegian Polar Institute and the <a href="https://www.npolar.no/sverdrup/">Sverdrup Station in Ny Ålesund</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/485687/original/file-20220920-3857-n3wiau.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/485687/original/file-20220920-3857-n3wiau.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485687/original/file-20220920-3857-n3wiau.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=346&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485687/original/file-20220920-3857-n3wiau.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=346&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485687/original/file-20220920-3857-n3wiau.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=346&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485687/original/file-20220920-3857-n3wiau.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485687/original/file-20220920-3857-n3wiau.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485687/original/file-20220920-3857-n3wiau.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Monitoring glaciers over the years requires digging in the snow to install our instruments, which are powered by solar panels and batteries. But the Arctic is a difficult environment, and in retrieving our data we may discover stations broken by shifting glaciers or heavy snowstorms.</span>
<span class="attribution"><span class="source">C. Bouchayer, U. Nanni</span></span>
</figcaption>
</figure>
<h2>Back from the field</h2>
<p>Back from the field, long months pass, in front of our computer or around a table, converting, filtering, and comparing the curves drawn by our observations. We find that the dynamics of Kongsvegen are governed by a melting season from June to October, during which several thousands of litres of water flow every second over the surface and base of the glacier. The duration and intensity of such melting has been <a href="https://www.youtube.com/watch?v=7IQBn-Sg-gc">observed</a> to increase with the rising temperature due to climate change. </p>
<p>All this water lubricates the base of the glacier and causes an increase in the velocity and stresses inside the glacier. At the same time, we measure an increase in the intensity of glacial vibrations, related to hydrological noise and intense crevasse activity under the influence of summer heat and glacier acceleration. This summer we observed an increased presence of crevasses and measured an increase in stress compared to last year. This could be a sign of a strong acceleration or even destabilisation of the glacier. </p>
<p>Our team, together with several colleagues, is currently analysing these results to quantify the causes of these changes, and thus better understand what leads to the destabilisation of a glacier in a melting world. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/485685/original/file-20220920-3592-rfd7go.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/485685/original/file-20220920-3592-rfd7go.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485685/original/file-20220920-3592-rfd7go.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=544&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485685/original/file-20220920-3592-rfd7go.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=544&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485685/original/file-20220920-3592-rfd7go.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=544&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485685/original/file-20220920-3592-rfd7go.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=683&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485685/original/file-20220920-3592-rfd7go.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=683&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485685/original/file-20220920-3592-rfd7go.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=683&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">What do we see under the glacier? Time series of measurements collected on the Kongsvegen Glacier throughout our mission. The runoff (blue curve) represents the amount of liquid water flowing through the glacier. The force (red curve) represents the stress at the base of the glacier. The seismic power (black curve) represents the amount of ‘vibration’ within the glacier. The glacier velocity is shown with the green curve.</span>
</figcaption>
</figure>
<hr>
<p><em>Further reading:<br>
● <a href="https://blogs.egu.eu/divisions/cr/2022/06/03/cryoseismology/">“Did you know… that glaciers can sing?”</a>, a blog post about seismic measurements on glaciers.<br>
● <a href="https://labo.obs-mip.fr/multitemp/estimation-of-marmolada-glacier-collapse-volume-using-pleiades-imagery/">“Estimation of Marmolada glacier collapse volume using Pléiades imagery”</a>, a blog post explaining the Marmolada collapse.</em></p><img src="https://counter.theconversation.com/content/191041/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The MAMMAMIA project is funded by The Research Council of Norway in the FRIPRO-programme. The NFR-project number is 301837. The author thanks his collaborators (listed on here: <a href="https://www.mn.uio.no/geo/english/research/projects/mammamia/">https://www.mn.uio.no/geo/english/research/projects/mammamia/</a>).</span></em></p>Researchers from the University of Oslo have drilled to the bottom of the Kongsvegen glacier. Find out why and how they are listening to the destabilisation of Arctic glaciers: The MAMMAMIA project.Ugo Nanni, Research scientist, University of OsloLicensed as Creative Commons – attribution, no derivatives.