tag:theconversation.com,2011:/ca/topics/ice-loss-in-antarctica-74895/articlesIce loss in Antarctica – The Conversation2022-07-12T20:03:36Ztag:theconversation.com,2011:article/1855052022-07-12T20:03:36Z2022-07-12T20:03:36ZWe studied how the Antarctic ice sheet advanced and retreated over 10,000 years. It holds warnings for the future<figure><img src="https://images.theconversation.com/files/471742/original/file-20220630-18-u3m5bs.jpg?ixlib=rb-1.1.0&rect=19%2C141%2C4262%2C2375&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Richard Selwyn Jones</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Alarming stories from Antarctica are now more frequent than ever; the ice surface is <a href="https://theconversation.com/warmer-summers-threaten-antarcticas-giant-ice-shelves-because-of-the-lakes-they-create-180989">melting</a>, floating ice shelves are <a href="https://theconversation.com/conger-ice-shelf-has-collapsed-what-you-need-to-know-according-to-experts-180077">collapsing</a> and glaciers are <a href="https://theconversation.com/ice-world-antarcticas-riskiest-glacier-is-under-assault-from-below-and-losing-its-grip-178828">flowing faster</a> into the ocean.</p>
<p>Antarctica will be the largest source of future sea-level rise. Yet scientists <a href="https://theconversation.com/scientists-still-dont-know-how-far-melting-in-antarctica-will-go-or-the-sea-level-rise-it-will-unleash-166677">don’t know</a> exactly how this melting will unfold as the climate warms.</p>
<p>Our <a href="https://dx.doi.org/10.1038/s43017-022-00309-5">latest research</a> looks at how the Antarctic ice sheet advanced and retreated over the past 10,000 years. It holds stark warnings, and possibly some hope, for the future.</p>
<h2>The current imbalance</h2>
<p>Future sea-level rise presents one of the most significant challenges of climate change, with economic, environmental and societal impacts expected for coastal communities around the globe.</p>
<p>While it seems like a distant issue, the changes in Antarctica may soon be felt on our doorsteps, in the form of rising sea levels.</p>
<p>Antarctica is home to the world’s largest single mass of ice: the Antarctic ice sheet. This body of glacier ice is several kilometres thick, nestled on top of solid land. It covers entire mountain ranges beneath it. </p>
<p>The ice sheet “<a href="https://vimeo.com/133626869">flows</a>” over the land from the Antarctic interior and towards the surrounding ocean. As a whole it remains a solid mass, but its shape slowly deforms as the ice crystals move around. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/LSG8Dm-ZPzc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Although the ice sheet is a solid mass, the continuous movement of ice crystals results in the sheet “flowing” outwards to the ocean, while being replenished by snowfall from above.</span></figcaption>
</figure>
<p>While the ice sheet flows outward, snowfall from above replenishes it. This cycle is supposed to keep the system in balance, wherein balance is achieved when the ice sheet is gaining the same amount of ice as it’s losing to the ocean each year.</p>
<p>However, <a href="https://climate.nasa.gov/vital-signs/ice-sheets/">satellites</a> keeping watch from above show the ice sheet is currently <em>not</em> in balance. Over the past 40 years, it has lost more ice than it has gained. The result has been global rising sea levels. </p>
<p>But these historical observations span only four decades, limiting our understanding of how the ice sheet responds to climate change over much longer periods.</p>
<p>We wanted to look further back in time – before satellites – and even before the first polar explorers. For this, we needed natural archives.</p>
<h2>Digging up Antarctica’s past</h2>
<p>We brought together various natural archives to unearth how the Antarctic ice sheet changed over the past 10,000 years or so. These included:</p>
<ul>
<li>ice cores collected from Antarctica’s remote interior, which can show us how snow accumulated in the past</li>
<li>rocks collected from exposed mountain peaks, which reveal how the ice sheet has thickened or thinned with time</li>
<li>sediment cores collected from the seafloor, which reveal how the ice sheet margin – where the edge of the land ice meets the ocean – advanced or retreated</li>
<li>lake mud and old beaches, which reveal how the coastline changed in response to the ice sheet growing or shrinking.</li>
</ul>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471980/original/file-20220701-23-9ic6sl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Ice coring in Antarctica" src="https://images.theconversation.com/files/471980/original/file-20220701-23-9ic6sl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471980/original/file-20220701-23-9ic6sl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471980/original/file-20220701-23-9ic6sl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471980/original/file-20220701-23-9ic6sl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471980/original/file-20220701-23-9ic6sl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471980/original/file-20220701-23-9ic6sl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471980/original/file-20220701-23-9ic6sl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ice cores provide an archive of how snow accumulation changed in the past.</span>
<span class="attribution"><span class="source">Liz Thomas</span></span>
</figcaption>
</figure>
<p>When we started our research, I wasn’t sure what to expect. After all, this period of time was long considered fairly dull, with only small changes to the ice margin.</p>
<p>Nevertheless, we studied the many different natural archives one by one. The work felt like a 1,000-piece jigsaw puzzle, full of irregular-shaped pieces and seemingly no straight edge. But once we put them together, the pieces lined up and the picture was clear.</p>
<p>Most striking was a period of ice loss that took place in all regions of Antarctica about 10,000 to 5,000 years ago. It resulted in many metres of sea-level rise globally. </p>
<p>In some regions of Antarctica, however, this ice loss was then followed by ice gain during the past 5,000 years – and a corresponding global sea-level fall – as the ice sheet margin advanced to where it is today.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471988/original/file-20220701-24-qnee74.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/471988/original/file-20220701-24-qnee74.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471988/original/file-20220701-24-qnee74.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471988/original/file-20220701-24-qnee74.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471988/original/file-20220701-24-qnee74.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471988/original/file-20220701-24-qnee74.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471988/original/file-20220701-24-qnee74.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471988/original/file-20220701-24-qnee74.jpeg?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">Cores of sediment collected from the seafloor tell us when the ice sheet retreated.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>A warning</h2>
<p>Understanding <em>how</em> and <em>why</em> the Antarctic ice sheet changed in this fashion offers lessons for the future.</p>
<p>The first lesson is more of a warning. The period of ice loss from 10,000 to 5,000 years ago was rapid, occurring at a similar rate to the most dramatically changing parts of the Antarctic ice sheet today. </p>
<p>We think it was likely the result of warm ocean water melting the underside of floating ice shelves – something that has also happened in recent decades. These ice shelves hold back the ice on land, so once they’re removed the ice on the land flows faster into the ocean. </p>
<p>In the future, it’s predicted ice loss will <a href="https://youtu.be/XRUxTFWWWdY?t=149">accelerate</a> as the ice sheet retreats into basins below sea level. This may already be under way in some regions of Antarctica. And based on what happened in the past, the resulting ice loss could persist for centuries.</p>
<h2>Bouncing back</h2>
<p>The second lesson from our work may bring some hope. Some 5,000 years ago the ice sheet margin stopped retreating in most locations, and in some regions actually started to advance. One explanation for this relates to the previous period of ice loss.</p>
<p>Before the ice began melting away, the Antarctic ice sheet was much heavier, and its weight pushed down into the Earth’s crust (which sits atop a molten interior). As the ice sheet melted and became lighter, the land beneath it would have lifted up – effectively hauling the ice out of the ocean.</p>
<p>Another possible explanation is climate change. At Antarctica’s coastal fringe, the ocean may have temporarily switched from warmer to cooler waters around the time the ice sheet began advancing again. At the same time, more snowfall took place at the top of the ice sheet.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471767/original/file-20220630-26-nzfc55.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/471767/original/file-20220630-26-nzfc55.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471767/original/file-20220630-26-nzfc55.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=456&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471767/original/file-20220630-26-nzfc55.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=456&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471767/original/file-20220630-26-nzfc55.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=456&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471767/original/file-20220630-26-nzfc55.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=573&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471767/original/file-20220630-26-nzfc55.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=573&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471767/original/file-20220630-26-nzfc55.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=573&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ice loss and ice gain were driven by several factors over the past 10,000 years, many of which are predicted to occur in the future.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>Our research supports the idea that the Antarctic ice sheet is poised to lose more ice and raise sea levels – particularly if the ocean continues to warm.</p>
<p>It also suggests uplift of the land and increased snowfall have the potential to slow or offset ice loss. However, this effect is not certain. </p>
<p>The past can never be a perfect test for the future. And considering the planet is <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf">warming faster</a> now than it was back then, we must err on the side of caution.</p>
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Read more:
<a href="https://theconversation.com/scientists-in-antarctica-discover-a-vast-salty-groundwater-system-under-the-ice-sheet-with-implications-for-sea-level-rise-182506">Scientists in Antarctica discover a vast, salty groundwater system under the ice sheet – with implications for sea level rise</a>
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</em>
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<img src="https://counter.theconversation.com/content/185505/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Selwyn Jones receives funding from the Australian Research Council. </span></em></p>Interestingly, we also found a major period of ice loss in Antarctica was followed by a period of gain, starting some 5,000 years ago.Richard Selwyn Jones, Research Fellow, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1764562022-02-10T22:32:25Z2022-02-10T22:32:25ZExploring Antarctica’s hidden under-ice rivers and their role in future sea-level rise<figure><img src="https://images.theconversation.com/files/444633/original/file-20220206-999-16ycn4h.jpg?ixlib=rb-1.1.0&rect=53%2C44%2C2907%2C1127&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The project's drill rig on the slopes of the Kamb Ice Stream. </span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>Underneath Antarctica’s vast ice sheets there’s a network of rivers and lakes. This is possible because of the insulating blanket of ice above, the flow of heat from within the Earth, and the small amount of heat generated as the ice deforms. </p>
<figure class="align-center ">
<img alt="Map of Antarctica showing sub-glacial rivers, ice flow velocity, and ocean depth." src="https://images.theconversation.com/files/445382/original/file-20220209-19-tr3a13.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/445382/original/file-20220209-19-tr3a13.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=453&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445382/original/file-20220209-19-tr3a13.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=453&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445382/original/file-20220209-19-tr3a13.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=453&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445382/original/file-20220209-19-tr3a13.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445382/original/file-20220209-19-tr3a13.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445382/original/file-20220209-19-tr3a13.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This map shows rivers (white) beneath Antarctica’s ice sheets (grey). Warm colours denote regions of fast ice flow.</span>
<span class="attribution"><span class="source">Huw Horgan/Quantarctica3/K862</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Water lubricates the base of the ice sheets, allowing the ice to slide towards the ocean at speeds of many hundreds of metres per year. When the water emerges from beneath the ice, it enters a cold and salty cavity underneath ice shelves, the floating extensions of ice sheets that fringe the continent.</p>
<p>Here the water mixes, releases nutrients and sediment, and melts the underside of the ice shelves, which act as buttresses and hold back the flow of the ice sheets. </p>
<p>How these processes play out over the next centuries is a major factor in <a href="https://theconversation.com/widespread-collapse-of-west-antarcticas-ice-sheet-is-avoidable-if-we-keep-global-warming-below-2-169651">understanding sea-level rise</a>. Unfortunately, this is also one of the least-explored parts of our planet.</p>
<p>Our <a href="https://www.antarcticscienceplatform.org.nz/">Aotearoa New Zealand Antarctic Science Platform</a> project is the first direct survey of an Antarctic under-ice river, and it supports <a href="https://doi.org/10.1130/G34654.1">earlier research</a> suggesting these sub-glacial rivers form estuaries as they flow into the ocean, albeit at 82.5 degrees south, hidden under 500m of ice and about 500km from the open ocean.</p>
<h2>Exploring an under-ice river</h2>
<p>Our team has just returned from Kamb Ice Stream on the West Antarctic Ice Sheet (<a href="https://www.antarcticglaciers.org/antarctica-2/west-antarctic-ice-sheet-2/west-antarctic-ice-sheet/">WAIS</a>). Kamb is a sleeping giant. </p>
<p>This massive river of ice lies on the other side of the WAIS from Thwaites Glacier, Antarctica’s “<a href="https://www.theguardian.com/world/2022/feb/02/antarctica-doomsday-glacier-scientists-frustrated-iceberg">doomsday</a>” glacier which has been losing ice rapidly. Kamb used to flow fast, but this ceased about 160 years ago because of changes in how water was distributed at the base of the ice.</p>
<figure class="align-center ">
<img alt="Scientists surveying over Antarctica's ice sheet and snow with skidoo and sleds." src="https://images.theconversation.com/files/445361/original/file-20220209-13-edv7f4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/445361/original/file-20220209-13-edv7f4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=306&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445361/original/file-20220209-13-edv7f4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=306&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445361/original/file-20220209-13-edv7f4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=306&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445361/original/file-20220209-13-edv7f4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=385&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445361/original/file-20220209-13-edv7f4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=385&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445361/original/file-20220209-13-edv7f4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=385&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Surveying across the surface of the under-ice river channel (in early 2016), researchers use seismic methods to determine what lies underneath the thick cover of ice.</span>
<span class="attribution"><span class="source">Huw Horgan/K862/VUW</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>While the Kamb region isn’t vulnerable to ocean warming at the present time, it currently offsets much of the ice loss happening elsewhere in Antarctica. Changes at Kamb will herald major changes for Antarctica’s ice sheets and oceans. </p>
<p>One challenge is that ice sheets respond to external changes, such as rising ocean temperatures, but also to difficult-to-predict internal changes, such as flood events that occur when sub-ice rivers and lakes “<a href="https://doi.org/10.1038/s43017-021-00246-9">burst their banks</a>”.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/antarcticas-doomsday-glacier-how-its-collapse-could-trigger-global-floods-and-swallow-islands-173940">Antarctica's 'doomsday' glacier: how its collapse could trigger global floods and swallow islands</a>
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</em>
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<h2>Getting there</h2>
<p>The COVID pandemic has been hard on national Antarctic programmes and the field science they support. Global supply and freight delays kept our team on the edge in the lead-up to our season. </p>
<p>This summer, New Zealand started the <a href="https://www.scottbaseredevelopment.govt.nz/">rebuild</a> of its main Antarctic station, Scott Base, and has been developing an over-snow traverse to deploy large teams across great distances. Our Kamb team was one of the first to benefit from this new capability, with a camp operating for months, more than 900km from New Zealand’s permanent station. </p>
<p>There’s an art to <a href="https://doi.org/10.1098/rsta.2014.0304">drilling through Antarctic ice</a>. In reality, we melt our way through with recycled hot water. </p>
<p>Once on site, the team was able to drill through 500m of the ice shelf and keep a 0.4m-diameter hole open for nearly two weeks. This allowed us to take samples and gather observations for a diverse range of science projects.</p>
<figure class="align-center ">
<img alt="A group of engineers swarm around a frame to help lower equipment designed to melt a hole in the ice shelf." src="https://images.theconversation.com/files/444636/original/file-20220206-25-14tfp2b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/444636/original/file-20220206-25-14tfp2b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/444636/original/file-20220206-25-14tfp2b.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/444636/original/file-20220206-25-14tfp2b.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/444636/original/file-20220206-25-14tfp2b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/444636/original/file-20220206-25-14tfp2b.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/444636/original/file-20220206-25-14tfp2b.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A group of engineers swarm around a frame to help lower equipment designed to melt a hole in the ice shelf.</span>
<span class="attribution"><span class="source">Craig Stevens/K862/NIWA</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A hidden river</h2>
<p>Almost a decade of research paid off when the team pinpointed the exact spot to drill to hit the onset of the narrow river beneath. This was even more impressive than initially thought, with borehole surveys revealing a river more than 240m high but less than 200m wide – a much narrower target than indicated by the surface icescape.</p>
<p>Working from a borehole means we can only look in one spot. As an antidote to this limitation, colleagues from Cornell University deployed their ocean robot Icefin to study the space below the ice.</p>
<figure class="align-center ">
<img alt="Underwater image showing complex variations in the ice underside." src="https://images.theconversation.com/files/444635/original/file-20220206-19-g4az4a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/444635/original/file-20220206-19-g4az4a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/444635/original/file-20220206-19-g4az4a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/444635/original/file-20220206-19-g4az4a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/444635/original/file-20220206-19-g4az4a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/444635/original/file-20220206-19-g4az4a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/444635/original/file-20220206-19-g4az4a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The camera shows corrugations on the underside of the ice.</span>
<span class="attribution"><span class="source">Craig Stevens/K862/NIWA</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>One of the discoveries that will keep the team going for some time is a dense community of likely amphipods, which we spotted when we lowered cameras to the seafloor. The swarm was so dense, we first thought there was something wrong with our equipment.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-an-ocean-hidden-under-antarctic-ice-reveals-about-our-planets-future-climate-139110">What an ocean hidden under Antarctic ice reveals about our planet's future climate</a>
</strong>
</em>
</p>
<hr>
<p>The last task the team completed was to deploy an ocean mooring beneath the ice. These instruments will continue to report back on ocean conditions over the coming years. </p>
<p>Only five days after deployment, we detected the tsunami from the <a href="https://theconversation.com/why-the-volcanic-eruption-in-tonga-was-so-violent-and-what-to-expect-next-175035">Hunga Tonga-Hunga Ha'apai volcanic eruption</a>. </p>
<figure class="align-center ">
<img alt="An image of camera equipment being lowered down a hole in the ice shelf. The camera is lighting up the walls of the hole, showing complex corrugations in the ice." src="https://images.theconversation.com/files/444634/original/file-20220206-23-1e663zm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/444634/original/file-20220206-23-1e663zm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=358&fit=crop&dpr=1 600w, https://images.theconversation.com/files/444634/original/file-20220206-23-1e663zm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=358&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/444634/original/file-20220206-23-1e663zm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=358&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/444634/original/file-20220206-23-1e663zm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=449&fit=crop&dpr=1 754w, https://images.theconversation.com/files/444634/original/file-20220206-23-1e663zm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=449&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/444634/original/file-20220206-23-1e663zm.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">
<figcaption>
<span class="caption">The team lowers camera equipment down the ice borehole, which is around 0.4m in diameter.</span>
<span class="attribution"><span class="source">Craig Stevens/K862/NIWA</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Apart from baseline observations, such discoveries provide strong motivation for deploying long-term monitoring equipment. The team will be watching closely over the coming years for any changes in the under-ice river flow, including flood events.</p><img src="https://counter.theconversation.com/content/176456/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Huw Horgan is part of the Antarctic Research Centre and School of Geography Environment and Earth Sciences at Te Herenga Waka - Victoria University of Wellington. He receives funding from the New Zealand Ministry for Business, Innovation and Employment (MBIE) Antarctica New Zealand Antarctic Science Platform (ASP), MBIE Strategic Science Investment Fund. He is also a Rutherford Discovery Fellow funded by MBIE through the New Zealand Royal Society.</span></em></p><p class="fine-print"><em><span>Craig Stevens has a joint position at NIWA and the University of Auckland and receives funding from the New Zealand Ministry for Business, Innovation and Employment (MBIE) Antarctica New Zealand Antarctic Science Platform (ASP), MBIE Strategic Science Investment Fund and the New Zealand Royal Society Te Apārangi Marsden Fund. He is on the Council of the New Zealand Association of Scientists. </span></em></p>Researchers have surveyed an Antarctic under-ice river for the first time directly, and their observations support the idea that such sub-glacial rivers form estuaries as they flow into the ocean.Huw Joseph Horgan, Associate Professor of Geophysical Glaciology, Te Herenga Waka — Victoria University of WellingtonCraig Stevens, Professor in Ocean Physics, National Institute of Water and Atmospheric ResearchLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1296072020-01-24T13:37:47Z2020-01-24T13:37:47Z200 years of exploring Antarctica – the world’s coldest, most forbidding and most peaceful continent<figure><img src="https://images.theconversation.com/files/311478/original/file-20200122-32136-14li66.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5355%2C3186&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Aerial view of a glacier in the Antarctic peninsula region.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/glacier-flows-as-seen-from-nasas-operation-icebridge-news-photo/870893786?adppopup=true">Getty Images/Mario Tama</a></span></figcaption></figure><p>Antarctica is the remotest part of the world, but it is a hub of scientific discovery, international diplomacy and environmental change. It was officially discovered 200 years ago, on Jan. 27, 1820, when members of a Russian expedition sighted land in what is now known as the Fimbul Ice Shelf on the continent’s east side. </p>
<p>Early explorers were drawn there by the mythology of <a href="https://lib-dbserver.princeton.edu/visual_materials/maps/websites/pacific/pacific-ocean/terra-australis.html">Terra Australis</a>, a vast southern continent that scholars imagined for centuries as a counterweight to the Northern Hemisphere. Others sought economic bounty from <a href="https://doi.org/10.1017/S0032247416000644">hunting whales and seals</a>, or the glory of conquering the planet’s last wilderness. Still others wanted to <a href="https://www.bgs.ac.uk/research/highlights/2012/terraNova.html">understand Earth’s magnetic fields</a> in order to better navigate the seas. </p>
<p>I am a <a href="https://scholar.google.com/citations?user=2atjAwMAAAAJ&hl=en">geologist</a> who specializes in understanding the timing and extent of past ice ages. Much of my work focuses on the glacial history of Antarctica, and I’ve been privileged to conduct five field seasons of research there. </p>
<p>For the next two years I’ll be working with a field team made up entirely of undergraduate students from Vanderbilt University to determine whether the <a href="https://en.wikipedia.org/wiki/East_Antarctic_Ice_Sheet">East Antarctic Ice Sheet</a> changes flow patterns as it changes shape. All of the research these budding scientists conduct will be done under the auspices of the <a href="https://www.ats.aq/index_e.html">Antarctic Treaty</a>, a global agreement that promotes scientific cooperation and environmental protection.</p>
<h2>Frozen but abundant</h2>
<p>Antarctica separated from South America 35 million years ago, and its climate started to change. It began to grow <a href="https://nsidc.org/cryosphere/quickfacts/icesheets.html">ice sheets</a> – masses of glacial land ice covering thousands of square miles. As plate tectonics shifted other continents, Antarctica became colder and drier. For the past 14 million years, it has been the frigid continent that persists today. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/311477/original/file-20200122-117962-1knrm08.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/311477/original/file-20200122-117962-1knrm08.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/311477/original/file-20200122-117962-1knrm08.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/311477/original/file-20200122-117962-1knrm08.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/311477/original/file-20200122-117962-1knrm08.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/311477/original/file-20200122-117962-1knrm08.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/311477/original/file-20200122-117962-1knrm08.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/311477/original/file-20200122-117962-1knrm08.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">Antarctica is mostly covered by ice sheets on land and fringed by floating ice shelves.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/news-features/features/antarctica-colder-arctic-it%E2%80%99s-still-losing-ice">NOAA</a></span>
</figcaption>
</figure>
<p>Antarctica is the only continent that was literally discovered, because it has no native human population. British explorer Sir James Cook circumnavigated the continent in 1772-1775, but saw only some outlying islands. Cook <a href="https://cudl.lib.cam.ac.uk/view/MS-JOD-00020/1">concluded</a> that if there were any land, it would be “condemned to everlasting regidity by Nature, never to yield to the warmth of the sun.” </p>
<p>Cook also reported that Antarctic waters were rich with nutrients and wildlife. This drew sealers and whalers, mainly from England and the United States, who hunted the region’s fur seals and elephant seals to <a href="https://doi.org/10.1017/S0032247416000644">near-extinction</a> in the following decades. This hunting spree led to the discovery of the Antarctic mainland and its ice sheets, the largest in the world.</p>
<h2>Reading the ice</h2>
<p>Today the combined East and West Antarctic ice sheets hold 90% of the world’s ice, enough to raise global sea levels by <a href="https://nsidc.org/cryosphere/quickfacts/icesheets.html">roughly 200 feet (60 meters) if it all melted</a>. Antarctica is the coldest, highest, driest, windiest, brightest, and yes, iciest continent on Earth. And 200 years of research has shown that it is a key component of Earth’s climate system.</p>
<p>Despite the appearance that it is an unchanging, freeze-dried landscape, my research and work by many others has shown that the East Antarctica Ice Sheet does slowly <a href="https://doi.org/10.1002/esp.2039">thin and thicken over millions of years</a>. Interestingly, my data also suggest that as the ice advances and retreats, it moves in <a href="https://gsa.confex.com/gsa/2016AM/webprogram/Paper285013.html">the same patterns each time</a>. Put another way, the ice flows over the same land each time it advances.</p>
<p>While East Antarctica adds and loses ice slowly, it is so large that it is a <a href="https://www.pnas.org/content/116/4/1095">major contributor to sea level rise</a>. Understanding how the ice has changed in the past is key to predicting how much and how fast it will melt in the coming years. </p>
<p>These questions are especially important in West Antarctica, where the bottom of the ice sheet is below sea level, making it very susceptible to changes in sea level and ocean temperature. By itself, the West Antarctic ice sheet has the potential to raise sea level by <a href="https://www.the-cryosphere.net/7/375/2013/">16 feet (5 meters) if it collapses</a>.</p>
<p>As climate change raises global sea levels, parts of the West Antarctica Ice Sheet, such as the <a href="https://thwaitesglacier.org/">Thwaites</a> and <a href="https://earthobservatory.nasa.gov/features/pine-island">Pine Island Glaciers</a>, are particularly vulnerable to collapse. At the end of the last ice age, parts of West Antarctica thinned by an average of <a href="https://science.sciencemag.org/content/299/5603/99">1.5 to 3 feet (0.5 - 1 meters) per year</a>. Today with GPS, satellite and airborne measurements, scientists are seeing parts of West Antarctica thin by <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2014GL060111">3 to 20 feet (1 to 6 meters) per year</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/YRe1ymYR45k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Antarctica is losing ice at an accelerating rate, partly due to climate change.</span></figcaption>
</figure>
<p>We also know from the geological record that this ice sheet is capable of rapid collapses, and has sometimes thinned at rates in excess of <a href="https://science.sciencemag.org/content/343/6174/999.abstract">30 feet (10 meters) per year</a>. Recent models show sea level could rise by <a href="https://www.nature.com/articles/nature17145">1 meter by 2100 and 15 meters by 2500</a> if greenhouse gas emissions continue to rise at current rates and the ice sheet experiences a rapid collapse, as it has in the past. </p>
<h2>Finding inspiration in scientific diplomacy</h2>
<p>Despite the potential for environmental disaster in Antarctica, the continent also offers evidence that nations can collaborate to find solutions. The <a href="https://www.scar.org/policy/antarctic-treaty-system/">Antarctic Treaty System</a> is the world’s premier example of peaceful and scientific international cooperation. </p>
<p>This landmark accord, signed in 1961, sets aside Antarctica for peaceful and scientific purposes and recognizes no land claims on the continent. It also was the first non-nuclear accord ever signed, barring use of Antarctica for nuclear weapons testing or disposal of radioactive waste.</p>
<p>The great Antarctic explorer <a href="http://www.bbc.co.uk/history/historic_figures/shackleton_ernest.shtml">Sir Ernest Shackleton</a> said that “optimism is true moral courage,” and the authors of the Antarctic Treaty were certainly courageous optimists. They were encouraged by the success of the 1957-1958 <a href="https://www.britannica.com/event/International-Geophysical-Year">International Geophysical Year</a>, a worldwide program of scientific research during which 12 countries built over 50 bases in Antarctica, including <a href="https://www.nsf.gov/geo/opp/support/mcmurdo.jsp">McMurdo Station</a> and the <a href="https://www.nsf.gov/geo/opp/support/southp.jsp">Amundsen-Scott South Pole Station</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/311481/original/file-20200122-32188-wqqhfn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/311481/original/file-20200122-32188-wqqhfn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/311481/original/file-20200122-32188-wqqhfn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=359&fit=crop&dpr=1 600w, https://images.theconversation.com/files/311481/original/file-20200122-32188-wqqhfn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=359&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/311481/original/file-20200122-32188-wqqhfn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=359&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/311481/original/file-20200122-32188-wqqhfn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=451&fit=crop&dpr=1 754w, https://images.theconversation.com/files/311481/original/file-20200122-32188-wqqhfn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=451&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/311481/original/file-20200122-32188-wqqhfn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=451&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Flags of the 12 original Antarctic Treaty member countries at McMurdo Station, Antarctica.</span>
<span class="attribution"><a class="source" href="https://antarcticsun.usap.gov/features/4410/">U.S. Antarctic Program/Rob Jones</a></span>
</figcaption>
</figure>
<p>Under the treaty, scientists from North Korea, Russia and China can freely visit U.S. research stations in Antarctica. Researchers from India and Pakistan willingly share their data about Antarctic glaciers. </p>
<p>Thanks to the Antarctic Treaty, 10% of Earth’s land surface is protected as a wildlife and wilderness refuge. I have set foot in places in Antarctica where I know no one has ever been before, and the treaty sets areas aside that no one will ever visit. Antarctica’s landscapes are unlike anywhere else on Earth. The best comparison may be the Moon. </p>
<p>Yet in these stark environments, <a href="https://www.bas.ac.uk/about/antarctica/wildlife/">life finds a way to persist</a> – showing that there are solutions to even the most daunting challenges. If Antarctica has taught us anything in 200 years, it’s that we can cooperate and collaborate to overcome problems. As <a href="https://www.bbc.co.uk/programmes/profiles/WTfFSJCJ5jkqnGPm4fqHyy/ernest-shackleton">Ernest Shackleton once said</a>, “Difficulties are just things to overcome, after all.” </p>
<p>[ <em><a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=thanksforreading">Thanks for reading! We can send you The Conversation’s stories every day in an informative email. Sign up today.</a></em> ]</p><img src="https://counter.theconversation.com/content/129607/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dan Morgan receives funding from the National Science Foundation.</span></em></p>Two centuries after it was first sighted by Russian explorers, Antarctica is a key site for studying the future of Earth’s climate – and for global scientific cooperation.Dan Morgan, Associate Dean and Principal Senior Lecturer in Earth and Environmental Sciences, Vanderbilt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1263202019-11-07T19:12:34Z2019-11-07T19:12:34ZEmperor Penguins could march to extinction if nations fail to halt climate change<figure><img src="https://images.theconversation.com/files/300526/original/file-20191106-12506-1t8jlj1.JPG?ixlib=rb-1.1.0&rect=0%2C0%2C5607%2C3732&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Emperor Penguin in Antarctica. </span> <span class="attribution"><span class="source">Stephanie Jenouvrier</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>The concept of a <a href="https://www.smithsonianmag.com/smart-news/story-real-canary-coal-mine-180961570/">canary in a coal mine</a> – a sensitive species that provides an alert to danger – originated with British miners, who carried actual canaries underground through the mid-1980s to detect the presence of deadly carbon monoxide gas. Today another bird, the Emperor Penguin, is providing a similar warning about the planetary effects of burning fossil fuels.</p>
<p>As a <a href="https://web.whoi.edu/jenouvrier/">seabird ecologist</a>, I develop mathematical models to understand and predict <a href="https://scholar.google.com/citations?user=E9vG0JoAAAAJ&hl=en">how seabirds respond to environmental change</a>. My research integrates many areas of science, including the expertise of <a href="https://staff.ucar.edu/users/mholland">climatologists</a>, to improve our ability to anticipate future ecological consequences of climate change. </p>
<p>Most recently, I worked with colleagues to combine what we know about the life history of Emperor Penguins with different potential <a href="https://doi.org/10.1002/2016GL069563">climate scenarios</a> outlined in the 2015 <a href="https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement">Paris Agreement</a>, to combat climate change and adapt to its effects. We wanted to understand how climate change could affect this iconic species, whose unique life habits were documented in the award-winning film “<a href="https://www.imdb.com/title/tt0428803/">March of the Penguins</a>.” </p>
<p>Our <a href="https://doi.org/10.1111/gcb.14864">newly published study</a> found that if climate change continues at its current rate, Emperor Penguins could virtually disappear by the year 2100 due to loss of Antarctic sea ice. However, a more aggressive global climate policy can halt the penguins’ march to extinction. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/300527/original/file-20191106-12521-1x20i4x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/300527/original/file-20191106-12521-1x20i4x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/300527/original/file-20191106-12521-1x20i4x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/300527/original/file-20191106-12521-1x20i4x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/300527/original/file-20191106-12521-1x20i4x.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/300527/original/file-20191106-12521-1x20i4x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/300527/original/file-20191106-12521-1x20i4x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/300527/original/file-20191106-12521-1x20i4x.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">Emperor Penguins breeding on sea ice in Terre Adélie, Antarctica.</span>
<span class="attribution"><span class="source">Stephanie Jenouvrier</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Carbon dioxide in Earth’s atmosphere</h2>
<p>As many scientific reports have shown, human activities are increasing carbon dioxide concentrations in Earth’s atmosphere, which is <a href="https://www.ipcc.ch/sr15/">warming the planet</a>. Today atmospheric CO2 levels stand at slightly over 410 parts per million, well above anything the planet has experienced in <a href="https://doi.org/10.1038/s41586-019-1692-3">millions of years</a>. </p>
<p>If this trend continues, scientists project that CO2 in the atmosphere could reach 950 parts per million by 2100. These conditions would produce <a href="https://www.ipcc.ch/report/ar5/syr/">a very different world</a> from today’s. </p>
<p>Emperor Penguins are <a href="https://doi.org/10.1016/j.biocon.2019.108216">living indicators</a> whose population trends can illustrate the consequences of these changes. Although they are found in Antarctica, far from human civilization, they live in such delicate balance with their rapidly changing environment that they have become modern-day canaries. </p>
<h2>A fate tied to sea ice</h2>
<p>I have spent almost 20 years studying Emperor Penguins’ unique adaptations to the <a href="https://doi.org/10.1890/08-2289.1">harsh conditions of their sea ice home</a>. Each year, the surface of the ocean around Antarctica freezes over in the winter and melts back in summer. Penguins use the ice as a home base for breeding, feeding and molting, arriving at their colony from ocean waters in March or April after sea ice has formed for the Southern Hemisphere’s winter season. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/300691/original/file-20191107-10952-133d77a.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/300691/original/file-20191107-10952-133d77a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/300691/original/file-20191107-10952-133d77a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/300691/original/file-20191107-10952-133d77a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/300691/original/file-20191107-10952-133d77a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/300691/original/file-20191107-10952-133d77a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/300691/original/file-20191107-10952-133d77a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/300691/original/file-20191107-10952-133d77a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">54 known Emperor Penguin colonies around Antarctica (black dots) and sea ice cover (blue color).</span>
<span class="attribution"><span class="source">Stephanie Jenouvrier</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In mid-May the female lays a single egg. Throughout the winter, males keep the eggs warm while females make a long trek to open water to feed during the most unforgiving weather on Earth.</p>
<p>When female penguins return to their newly hatched chicks with food, the males have fasted for four months and lost almost half their weight. After the egg hatches, both parents take turns feeding and protecting their chick. In September, the adults leave their young so that they can both forage to meet their chick’s growing appetite. In December, everyone leaves the colony and returns to the ocean. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/k0u67Wk_hJ0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Emperor Penguin fathers incubate a single egg until it hatches.</span></figcaption>
</figure>
<p>Throughout this annual cycle, the penguins rely on a sea ice “<a href="https://doi.org/10.1111/j.1365-2486.2012.02744.x">Goldilocks zone</a>” of conditions to thrive. They need openings in the ice that provide access to the water so they can feed, but also a thick, stable platform of ice to raise their chicks. </p>
<h2>Penguin population trends</h2>
<p>For more than 60 years, scientists have extensively studied one Emperor Penguin colony in Antarctica, called <a href="https://doi.org/10.1038/35075554">Terre Adélie</a>. This research has enabled us to understand how sea ice conditions affect the birds’ <a href="https://doi.org/10.1890/05-0514">population dynamics</a>. In the 1970s, for example, the population experienced a <a href="https://doi.org/10.1098/rspb.2004.2978">dramatic decline</a> when several consecutive years of low sea ice cover caused <a href="https://doi.org/10.1038/35075554">widespread deaths</a> among male penguins. </p>
<p>Over the past 10 years, my colleagues and I have combined what we know about these relationships between sea ice and fluctuations in penguin life histories to create a <a href="https://www.jstor.org/stable/pdf/10.1086/652436.pdf">demographic model</a> that allows us to understand how sea ice conditions affect the <a href="https://doi.org/10.1111/j.1365-2486.2012.02744.x">abundance of Emperor Penguins</a>, and to project their numbers based on forecasts of future sea ice cover in Antarctica.</p>
<p>Once we confirmed that our model <a href="https://doi.org/10.1038/nclimate2280">successfully reproduced past observed trends</a> in Emperor Penguin populations around all Antarctica, we expanded our analysis into a species-level threat assessment.</p>
<h2>Climate conditions determine emperor penguins’ fate</h2>
<p>When we used a climate model linked to our population model to project what is likely to happen to sea ice if greenhouse gas emissions continue on their present trend, we found that all 54 known Emperor Penguin colonies would be in decline by 2100, and 80% of them would be quasi-extinct. Accordingly, we estimate that the total number of Emperor Penguins will decline by 86% relative to its <a href="https://doi.org/10.1371/journal.pone.0033751">current size</a> of roughly 250,000 if nations fail to reduce their carbon dioxide emissions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/300692/original/file-20191107-10901-p3dyta.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/300692/original/file-20191107-10901-p3dyta.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/300692/original/file-20191107-10901-p3dyta.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/300692/original/file-20191107-10901-p3dyta.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/300692/original/file-20191107-10901-p3dyta.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/300692/original/file-20191107-10901-p3dyta.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/300692/original/file-20191107-10901-p3dyta.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/300692/original/file-20191107-10901-p3dyta.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Without action to reduce global carbon dioxide emissions, sea ice loss (shown in blue) will eradicate most Emperor Penguin colonies by 2100.</span>
<span class="attribution"><span class="source">Stephanie Jenouvrier</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>However, if the global community acts to reduce greenhouse gas emissions and succeeds in stabilizing average global temperatures at 1.5 degrees Celsius (3 degrees Faherenheit) above pre-industrial levels, we estimate that Emperor Penguin numbers would decline by 31% – still drastic, but viable.</p>
<p>Less-stringent cuts in greenhouse gas emissions, leading to a global temperature rise of 2°C, would result in a 44% decline. </p>
<p>Our model indicates that these population declines will occur predominately in the first half of this century. Nonetheless, in a scenario in which the world meets the Paris climate targets, we project that the global Emperor Penguin population would nearly stabilize by 2100, and that viable refuges would remain available to support some colonies. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/300560/original/file-20191107-12470-tqlnju.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/300560/original/file-20191107-12470-tqlnju.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/300560/original/file-20191107-12470-tqlnju.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=369&fit=crop&dpr=1 600w, https://images.theconversation.com/files/300560/original/file-20191107-12470-tqlnju.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=369&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/300560/original/file-20191107-12470-tqlnju.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=369&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/300560/original/file-20191107-12470-tqlnju.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=464&fit=crop&dpr=1 754w, https://images.theconversation.com/files/300560/original/file-20191107-12470-tqlnju.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=464&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/300560/original/file-20191107-12470-tqlnju.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=464&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Global action to limit climate change through 2100 could greatly improve Emperor Penguins’ persistence/viability.</span>
<span class="attribution"><span class="source">Stephanie Jenouvrier</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In a changing climate, individual penguins may move to new locations to find more suitable conditions. Our population model included complex <a href="https://doi.org/10.1016/j.biocon.2017.05.017">dispersal processes</a> to account for these movements. However, we find that these actions are not enough to offset climate-driven global population declines. In short, global climate policy has much more influence over the future of Emperor Penguins than the penguins’ ability to move to better habitat.</p>
<p>Our findings starkly illustrate the far-reaching implications of national climate policy decisions. Curbing carbon dioxide emissions has critical implications for Emperor Penguins and an untold number of other species for which science has yet to document such a plain-spoken warning.</p>
<p>[ <em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/126320/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephanie Jenouvrier receives funding from the National Science foundation, which supported the work described in this article. </span></em></p>Emperor Penguins thrive in harsh conditions, but a new study shows that their fate depends on human action to slow global warming and associated loss of sea ice.Stephanie Jenouvrier, Associate Scientist, Woods Hole Oceanographic InstitutionLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1218642019-08-14T20:01:06Z2019-08-14T20:01:06ZNew research shows that Antarctica’s largest floating ice shelf is highly sensitive to warming of the ocean<figure><img src="https://images.theconversation.com/files/287935/original/file-20190813-9442-wsmk2i.jpg?ixlib=rb-1.1.0&rect=32%2C124%2C4338%2C2785&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Since the last ice age, the ice sheet retreated over a thousand kilometres in the Ross Sea region, more than any other region on the continent.</span> <span class="attribution"><span class="source">Rich Jones</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Scientists have long been concerned about the <a href="https://www.nature.com/articles/271321a0">potential collapse of the West Antarctic Ice Sheet</a> and its contribution to global sea level rise. Much of West Antarctica’s ice lies below sea level, and warming ocean temperatures may lead to runaway ice sheet retreat. </p>
<p>This process, called marine ice sheet instability, has already been observed along parts of the Amundsen Sea region, where <a href="https://science.sciencemag.org/content/341/6143/266">warming of the ocean has led to melting underneath the floating ice shelves</a> that fringe the continent. As these ice shelves thin, the ice grounded on land flows more rapidly into the ocean and raises the sea level.</p>
<p>Although the Amundsen Sea region has shown the most rapid changes to date, more ice actually <a href="https://science.sciencemag.org/content/333/6048/1427">drains from West Antarctica via the Ross Ice Shelf</a> than any other area. How this ice sheet responds to climate change in the Ross Sea region is therefore a key factor in Antarctica’s contribution to global sea level rise in the future.</p>
<p>Periods of past ice sheet retreat can give us insights into how sensitive the Ross Sea region is to changes in ocean and air temperatures. Our <a href="https://advances.sciencemag.org/content/5/8/eaav8754">research</a>, published today, argues that ocean warming was a key driver of glacial retreat since the last ice age in the Ross Sea. This suggests that the Ross Ice Shelf is highly sensitive to changes in the ocean.</p>
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Read more:
<a href="https://theconversation.com/ice-melt-in-greenland-and-antarctica-predicted-to-bring-more-frequent-extreme-weather-111082">Ice melt in Greenland and Antarctica predicted to bring more frequent extreme weather</a>
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<h2>History of the Ross Sea</h2>
<p>Since the last ice age, the ice sheet <a href="https://www.sciencedirect.com/science/article/pii/S0277379113003338">retreated more than 1,000km in the Ross Sea region</a> – more than any other region on the continent. But there is little consensus among the scientific community about how much climate and the ocean have contributed to this retreat. </p>
<p>Much of what we know about the past ice sheet retreat in the Ross Sea comes from rock samples found in the Transantarctic Mountains. Dating techniques allow scientists to determine when these rocks were exposed to the surface as the ice around them retreated. These rock samples, which were collected far from where the initial ice retreat took place, have generally led to <a href="https://science.sciencemag.org/content/286/5438/280">interpretations</a> in which the ice sheet retreat happened much later than, and independently of, the rise in air and ocean temperatures following the last ice age.</p>
<p>But <a href="https://www.nature.com/articles/s41598-018-29911-8">radiocarbon ages from sediments</a> in the Ross Sea suggest an earlier retreat, more in line with when climate began to warm from the last ice age. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/287937/original/file-20190813-9409-pjv0by.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287937/original/file-20190813-9409-pjv0by.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287937/original/file-20190813-9409-pjv0by.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287937/original/file-20190813-9409-pjv0by.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287937/original/file-20190813-9409-pjv0by.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287937/original/file-20190813-9409-pjv0by.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287937/original/file-20190813-9409-pjv0by.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">An iceberg floating in the Ross Sea - an area that is sensitive to warming in the ocean.</span>
<span class="attribution"><span class="source">Rich Jones</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Using models to understand the past</h2>
<p>To investigate how sensitive this region was to past changes, we developed a regional model of the Antarctic ice sheet. The model works by simulating the physics of the ice sheet and its response to changes in ocean and air temperatures. The simulations are then compared to geological records to check accuracy.</p>
<p>Our main findings are that warming of the ocean and atmosphere were the main causes of the major glacial retreat that took place in the Ross Sea region since the last ice age. But the dominance of these two controls in influencing the ice sheet evolved through time. Although air temperatures influenced the timing of the initial ice sheet retreat, ocean warming became the main driver due to melting of the Ross Ice Shelf from below, similar to what is currently observed in the Amundsen Sea. </p>
<p>The model also identifies key areas of uncertainty of past ice sheet behaviour. Obtaining sediment and rock samples and oceanographic data would help to improve modelling capabilities. The <a href="https://science.sciencemag.org/content/333/6048/1427">Siple Coast region of the Ross Ice Shelf is especially sensitive to changes</a> in melt rates at the base of the ice shelf, and is therefore a critical region to sample.</p>
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<strong>
Read more:
<a href="https://theconversation.com/climate-scientists-explore-hidden-ocean-beneath-antarcticas-largest-ice-shelf-90006">Climate scientists explore hidden ocean beneath Antarctica's largest ice shelf</a>
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<h2>Implications for the future</h2>
<p>Understanding processes that were important in the past allows us to improve and validate our model, which in turn gives us confidence in our future projections. Through its history, the ice sheet in the Ross Sea has been sensitive to changes in ocean and air temperatures. Currently, ocean warming underneath the Ross Ice Shelf is the main concern, given its potential to cause melting from below. </p>
<p>Challenges remain in determining exactly how ocean temperatures will change underneath the Ross Ice Shelf in the coming decades. This will depend on changes to patterns of ocean circulation, with complex interactions and feedback between sea ice, surface winds and <a href="https://www.nature.com/articles/s41586-019-0889-9">melt water from the ice sheet</a>. </p>
<p>Given the sensitivity of ice shelves to ocean warming, we need an integrated modelling approach that can accurately reproduce both the ocean circulation and dynamics of the ice sheet. But the computational cost is high. </p>
<p>Ultimately, these integrated projections of the Southern Ocean and Antarctic ice sheet will help policymakers and communities to develop meaningful adaptation strategies for cities and coastal infrastructure exposed to the risk of rising seas.</p><img src="https://counter.theconversation.com/content/121864/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dan Lowry's PhD work is funded from the Royal Society Te Aparangi Marsden Fund through Victoria University of Wellington and the Antarctica New Zealand Doctoral Scholarship program.</span></em></p>New research shows that ocean and air temperatures both contributed to the melting of Antarctica’s Ross Ice Shelf in the past, but melting from below by a warming ocean became more important over time.Dan Lowry, PhD candidate, Te Herenga Waka — Victoria University of WellingtonLicensed as Creative Commons – attribution, no derivatives.