tag:theconversation.com,2011:/fr/topics/sea-levels-1049/articlesSea levels – The Conversation2024-01-25T13:16:51Ztag:theconversation.com,2011:article/2201202024-01-25T13:16:51Z2024-01-25T13:16:51ZFrom New York to Jakarta, land in many coastal cities is sinking faster than sea levels are rising<figure><img src="https://images.theconversation.com/files/567456/original/file-20231228-21-99pvh5.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C5991%2C3979&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Infrastructure can increase vulnerabilities to coastal cities like New York.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/new-york-city-skyline-royalty-free-image/523392100?phrase=new+york+sea+level+rise&searchscope=image%2Cfilm&adppopup=true">GlennisEhi/Getty Images</a></span></figcaption></figure><p><a href="https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level">Sea level rise</a> has already put coastal cities on notice thanks to increasing storm surges and even <a href="https://coast.noaa.gov/states/fast-facts/recurrent-tidal-flooding.html">sunny day</a> flooding at high tide. These challenges will continue to grow because global projections point to a mean sea level rise of at least one foot above year-2000 levels by the <a href="https://www.theguardian.com/environment/2023/jun/26/its-absolutely-guaranteed-the-best-and-worst-case-scenarios-for-sea-level-rise">end of this century</a>.</p>
<p>However, many cities are facing another factor making them even more vulnerable to rising waters: <a href="https://www.washingtonpost.com/climate-environment/2023/05/30/land-sinking-us-subsidence-sea-level/">land subsidence</a>. </p>
<p>The three of us – <a href="https://web.uri.edu/gso/meet/pei-chin-wu/">Pei-Chin Wu</a>, <a href="https://web.uri.edu/gso/meet/matt-wei/">Meng (Matt) Wei</a> and <a href="https://web.uri.edu/gso/meet/steven-dhondt/">Steven D'Hondt</a> – are scientists at the University of Rhode Island Graduate School of Oceanography working with the U.S. Geological Survey to research challenges facing waterfront cities. Our findings indicate that <a href="https://doi.org/10.1029/2022GL098477">land is sinking</a> faster than sea levels are rising in many coastal cities throughout the world. </p>
<p>By using radar images of the Earth’s surface collected from orbiting satellites, we measured subsidence rates in 99 coastal cities worldwide. These rates are highly variable within cities and from city to city, but if they continue, many metropolises will experience flooding much sooner than projected by sea level rise models.</p>
<p>Cities in South, Southeast and East Asia are seeing the most rapid rates of subsidence. </p>
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<figcaption><span class="caption">Taipei is sinking: University of Rhode Island | Taiwan News | RTI.</span></figcaption>
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<p><a href="https://www.nytimes.com/interactive/2023/05/16/headway/indonesia-nusantara-jakarta.html">Indonesia</a>, for example, is moving its capital 800 miles from Jakarta to Nusantara in large part because Jakarta is sinking at an alarming rate due to groundwater extraction. </p>
<p>Other regions are not immune. Our research with Tom Parsons of the U.S. Geological Survey found that most of <a href="https://doi.org/10.1029/2022EF003465">New York City</a>is sinking between 1 to 4 millimeters per year due to a combination of <a href="https://oceanservice.noaa.gov/facts/glacial-adjustment.html">glacial rebound</a> and the weight of its more than 1 million buildings. In a city where sea level is projected to rise between 8 and 30 inches by 2050, subsidence <a href="https://www.uri.edu/news/2023/06/new-york-city-is-sinking-and-its-not-alone/">further increases its vulnerability</a> to coastal storms. </p>
<p>In the U.S., most of the cities on the Atlantic coast are subsiding due to glacial rebound. Even if the rate is low at minus-1 millimeter per year, it should be accounted. Other cities in the U.S., especially in the Gulf of Mexico, including Houston and New Orleans, also face subsidence. </p>
<p>Governments around the world are facing the challenge of coastal areas that are subsiding, and there is a shared global challenge of mitigation against a growing flooding hazard.</p>
<p>While our research continues to evolve – for example, by using machine learning to improve our monitoring capability – we urge city planners, emergency managers and other decision-makers to account for subsidence in the plans they are making today to prepare for the impacts of rising sea levels in the future.</p>
<p><em>Editor’s note: This story was updated to correct the rate at which New York City is sinking.</em></p><img src="https://counter.theconversation.com/content/220120/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pei-Chin Wu is working towards her PhD degree at the Graduate School of Oceanography at the University of Rhode Island and receives funding from the Ministry of Education in Taiwan.</span></em></p><p class="fine-print"><em><span>Steven D’Hondt receives funding from Rhode Island Sea Grant.</span></em></p><p class="fine-print"><em><span>Meng (Matt) Wei 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>Land subsidence is a factor as preparations are made for rising sea levels and strengthening storms. Human infrastructure, including buildings and groundwater extraction, increases vulnerabilities.Pei-Chin Wu, Ph.D. Candidate in Oceangraphy, University of Rhode IslandMeng (Matt) Wei, Associate Professor of Oceanography, University of Rhode IslandSteven D’Hondt, Professor of Oceanography, Graduate School of Oceanography, University of Rhode IslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2211212024-01-17T04:10:46Z2024-01-17T04:10:46ZHow rising sea levels will affect our coastal cities and towns<p>Sea-level rise – along with <a href="https://www.csiro.au/en/news/All/News/2024/January/Expert-commentary-2023-warmest-year-on-record">increasing temperatures</a> – is one of the clearest signals of man-made global warming. Yet exactly how rising water levels affect the coast is often misunderstood. </p>
<p>A new <a href="https://www.marineandcoasts.vic.gov.au/coastal-programs/port-phillip-bay-coastal-hazard-assessment">coastal hazard assessment</a> for Victoria’s Port Phillip Bay has again thrown the spotlight on the impact of sea-level rise on coastal communities in Australia. Should we be worried? Or is the reality more nuanced?</p>
<p>While there are still many uncertainties, even a small change in sea level can have big impacts. We should be doing all we can to limit sea-level rise to protect our coastal cities and towns. And because sea levels will continue to rise for centuries after we cut emissions to net zero, planning decisions for coastal areas must factor this in.</p>
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<h2>Why are sea levels rising?</h2>
<p>Global sea levels are rising for two main reasons: the <a href="https://theconversation.com/ocean-heat-is-off-the-charts-heres-what-that-means-for-humans-and-ecosystems-around-the-world-207902">oceans are getting warmer</a>, and land-based <a href="https://theconversation.com/rising-seas-and-melting-glaciers-these-changes-are-now-irreversible-but-we-have-to-act-to-slow-them-down-165527">ice sheets and glaciers are melting</a>. </p>
<p>As ocean water warms, it expands. Because the ocean basins are finite (like a bathtub), this results in a rise in water levels. </p>
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<a href="https://theconversation.com/ocean-heat-is-off-the-charts-heres-what-that-means-for-humans-and-ecosystems-around-the-world-207902">Ocean heat is off the charts – here's what that means for humans and ecosystems around the world</a>
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<p>Since the 1970s, thermal expansion of the oceans has accounted for roughly <a href="https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level">half of measured global sea-level rise</a>. The other half is due to land-based ice melt from ice sheets and glaciers. Together, these make up what is known as “eustatic” sea level.</p>
<p>The rate of sea-level rise experienced at the coast also depends on whether the land is moving up or down. “Relative” or “isostatic” sea level is the sum of “eustatic” sea level plus local vertical land movement. </p>
<p>Australia is rising by about 0.3-0.4 millimetres a year due to <a href="https://www.cmar.csiro.au/sealevel/sl_impacts_sea_level.html">glacial isostatic adjustment</a>. This is the result of the land continuing to move upward following the loss of ice on land during <a href="https://www.sciencedirect.com/science/article/abs/pii/B978044453447700074X">previous glaciations</a>. The land subsided under the weight of this ice and is now rebounding as the ice is gone. This slow rebound of the land provides a small offset to eustatic sea levels around Australia.</p>
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Read more:
<a href="https://theconversation.com/rising-seas-and-melting-glaciers-these-changes-are-now-irreversible-but-we-have-to-act-to-slow-them-down-165527">Rising seas and melting glaciers: these changes are now irreversible, but we have to act to slow them down</a>
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<h2>Sea-level rise is accelerating</h2>
<p>From 1900 to 2018, global sea levels rose by <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter02.pdf">about 20cm</a> (a long-term average of 1.7mm/yr), but almost everywhere the rate of rise is increasing. Measurements since 1993, when global satellite data became available, show the rate of global mean sea-level rise over the past decade has more than doubled to <a href="https://www.nature.com/articles/s41467-021-21265-6">more than 4mm/yr</a>.</p>
<p>Around Australia, sea levels are rising at or above this global average. <a href="http://www.bom.gov.au/oceanography/projects/abslmp/abslmp.shtml">Tide gauges</a> indicate the rate of rise in northern Australia since the early 1990s is around 4–6mm/yr. Along the south-east coast of Australia, it’s about 2–4mm/yr. Rates of sea-level rise are not uniform around Australia because of local effects like ocean circulation and tidal processes. </p>
<p>Even if greenhouse gas emissions reached zero tomorrow, sea levels will continue to rise for several centuries because of the slow response of the ocean to warming. It’s a long-term trend that we must live with. </p>
<p>This is why is it important to factor in sea-level rise when we make planning decisions along the coast. Unfortunately, the rate of sea-level rise over the coming century remains highly uncertain, making it difficult to include in coastal planning.</p>
<p>The “likely” range of the most recent projections by the Intergovernmental Panel on Climate Change (<a href="https://www.ipcc.ch/">IPCC</a>) is a rise of <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf">between 0.4 metres and 0.8m</a> by 2100. However, a rise of nearly 2m by 2100 and 5m by 2150 cannot be ruled out. This is due to deep uncertainty about ice-sheet processes – so much so, that in 2021 the IPCC introduced a new <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf">high-end risk scenario</a> to describe this.</p>
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Read more:
<a href="https://theconversation.com/coastal-property-prices-and-climate-risks-are-both-soaring-we-must-pull-our-heads-out-of-the-sand-195357">Coastal property prices and climate risks are both soaring. We must pull our heads out of the sand</a>
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<h2>Small rises have big impacts</h2>
<p>The impact of sea-level rise at the coast is not just a gradual increase in water lapping at the shore. An increase in tide heights (both higher high tides and higher low tides) increases the probability of coastal flooding and erosion when storms come along.</p>
<p>As a rule of thumb, every 10cm of sea-level rise <a href="https://theconversation.com/climate-explained-why-coastal-floods-are-becoming-more-frequent-as-seas-rise-127202#">triples the frequency</a> of a given coastal flood. Another rule of thumb, known as the <a href="https://nccarf.edu.au/wp-content/uploads/2019/05/Rules-of-thumb-for-managing-coastal-processes.pdf">Bruun Rule</a>, suggests a 1cm rise in sea level leads to a 1m retreat of the coastline.</p>
<p>While these back-of-the-envelope estimates are often <a href="https://www.nature.com/articles/s41558-020-00934-2">significantly reduced when local conditions are accounted for</a>, it explains why a small shift in the mean sea level can have big impacts at the coast.</p>
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Read more:
<a href="https://theconversation.com/climate-explained-why-coastal-floods-are-becoming-more-frequent-as-seas-rise-127202">Climate explained: why coastal floods are becoming more frequent as seas rise</a>
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<h2>Storms aren’t always bad for the beach</h2>
<p>Most of the impacts of sea-level rise around Australia’s coast will be felt in combination with storm events, such as <a href="https://www.abc.net.au/news/2020-02-07/what-is-an-east-coast-low-wild-weekend-weather/11936190">east coast lows</a> or <a href="https://www.abc.net.au/news/2011-02-01/tropical-cyclones-explained/1926870">tropical cyclones</a>. A high water level plus a storm surge on top leads to a storm or “king” tide. In combination with storm waves, it can cause significant coastal erosion and flooding. </p>
<p>However, storms also bring sand from deeper water towards the beach. Over the long term, this process <a href="https://www.nature.com/articles/s43247-022-00437-2">can help beaches keep pace with sea-level rise</a>. Fortunately for eastern Australia, we have a lot of sand sitting offshore which is <a href="https://www.sciencedirect.com/science/article/abs/pii/S002532271630010X?via%3Dihub">slowly making its way back to our beaches</a>. Other naturally regressive coastlines, such as many in Northern Europe, are not so lucky.</p>
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Read more:
<a href="https://theconversation.com/become-a-beach-scientist-this-summer-and-help-monitor-changing-coastlines-214307">Become a beach scientist this summer and help monitor changing coastlines</a>
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<h2>All eyes on Antarctica</h2>
<p>Sea-level rise is here to stay and gathering pace, but the rate of future increase remains uncertain. It largely depends on what happens in Antarctica over the coming decades. </p>
<p>This in turn depends on land and sea temperatures around the southern continent, which are directly linked to our efforts to limiting global warming to 1.5°C in line with the <a href="https://unfccc.int/process-and-meetings/the-paris-agreement">Paris Agreement</a>. </p>
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<p>With over 250 million people now living on land <a href="https://www.nature.com/articles/s41467-021-23810-9">less than 2m above sea level</a>, most in Asia, it is imperative we do everything we can to limit future sea-level rise.</p><img src="https://counter.theconversation.com/content/221121/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thomas Mortlock works as a senior analyst for Aon Reinsurance Solutions Australia.</span></em></p>Even a small rise in sea level can have big impacts on coastal properties, so we must do all we can to limit the changes while taking them into account in coastal land-use planning.Thomas Mortlock, Adjunct Fellow, Climate Change Research Centre, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2173532023-11-16T22:57:51Z2023-11-16T22:57:51ZLet coastlines be coastlines: How nature-based approaches can protect Canada’s coasts<p>Along Canadian coasts, <a href="https://www.queensu.ca/gazette/stories/climate-change-means-atlantic-canada-will-see-more-frequent-storms">storm surges</a> and <a href="https://www.uottawa.ca/environment/blog/100-year-floods-are-increasing-canada-due-climate-change-officials-say-true">flooding</a> have gone from breaking news to seasonal norms. </p>
<p>Phenomena Canadians have historically thought of as freak <a href="https://doi.org/10.1080/24694452.2020.1744423">natural disasters are becoming regular predictable occurrences</a>. </p>
<p>Our go-to solution to protect property and infrastructure is to build walls to block wave energy — walls that have become <a href="https://www.researchgate.net/profile/Ca-Vu/publication/346517536_Coastal_Development_Resilience_Restoration_and_Infrastructure_Requirements_LEAD_AUTHORS_About_the_High_Level_Panel_for_a_Sustainable_Ocean_Economy/links/5fc5e73992851c3012995ca6/Coastal-Development-Resilience-Restoration-and-Infrastructure-Requirements-LEAD-AUTHORS-About-the-High-Level-Panel-for-a-Sustainable-Ocean-Economy.pdf">ineffective and unaffordable</a>. It’s time to look beyond the status quo and consider <a href="https://www.csagroup.org/article/research/nature-based-solutions-for-coastal-and-riverine-flood-and-erosion-risk-management/">nature-based solutions</a> to protect the places we love.</p>
<h2>How we got here</h2>
<p>In many parts of the world, humans have long felt a <a href="https://press.uchicago.edu/ucp/books/book/chicago/H/bo14312647.html">strong connection to the coast</a>. We <a href="https://doi.org/10.1016/B978-0-323-95227-9.00007-5">write stories, sing songs and build lives</a> on the lands that touch the sea. We also build walls and other concrete, stone and metal structures to <a href="https://oceanservice.noaa.gov/facts/shoreline-armoring.html">protect those lands</a> from the very seas we revere.</p>
<p>From time immemorial, Indigenous Peoples made their homes along the coasts, becoming <a href="https://pressbooks.bccampus.ca/knowinghome/chapter/chapter-7/">experts in their knowledge</a> of coastal ecosystems and, on the Atlantic and Pacific coasts, used <a href="https://www.ubcpress.ca/against-the-tides">salt marshes for food and transportation</a>. Following European settlement, those salt marshes were drained, <a href="https://www2.gov.bc.ca/gov/content/environment/air-land-water/water/drought-flooding-dikes-dams/integrated-flood-hazard-management/dike-management#:%7E:text=Dike%20consequence%20classification-,History%20of%20dikes%20in%20B.C.,relatively%20little%20damage%20was%20caused.">dykes</a> were built from earth and wood, and the land was cultivated for agriculture.</p>
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<a href="https://theconversation.com/storms-or-sea-level-rise-what-really-causes-beach-erosion-209213">Storms or sea-level rise – what really causes beach erosion?</a>
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<p><a href="https://books.google.ca/books?hl=en&lr=&id=AjwPEAAAQBAJ&oi=fnd&pg=PP1&dq=how+much+of+Canada%27s+coast+is+hardened+shoreline&ots=ofxRgZFp1q&sig=pudIoHph4rwpz4E5hntGfVx36uc#v=onepage&q=how%20much%20of%20Canada's%20coast%20is%20hardened%20shoreline&f=false">Over time, other hard armour structures</a> such as <a href="https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/agricultural-land-and-environment/water/drainage-management-guide/533410-1_rock_revetments-drainage_guide_factsheet_no12.pdf">revetments</a> and <a href="https://www.britannica.com/technology/breakwater">breakwaters</a> were constructed to block wave energy and provide additional protection for agriculture, transportation and growing cities.</p>
<h2>Where we are now</h2>
<p>Today, Canada’s coastal infrastructure includes extensive networks of seawalls, dykes, revetments and breakwaters, most of which are made of hard materials. Hard coastal infrastructure is everywhere if you know where to look. The <a href="https://transcanadahighway.com/nova-scotia/canso-causeway/">Canso Causeway</a> connecting Cape Breton Island to mainland Nova Scotia and the <a href="https://vancouver.ca/parks-recreation-culture/seawall.aspx">Vancouver seawall</a> are just two examples. </p>
<p>In some cases, using <a href="https://www.jstor.org/stable/48703231?seq=2">hard infrastructure</a> is unavoidable. Indeed, <a href="https://nrc.canada.ca/en/research-development/research-collaboration/programs/ocean-program-coastal-resilience-technology-theme">hard infrastructure</a> is critical for maintaining transportation and energy infrastructure, including roads, railroads and ports. </p>
<p>However, hard infrastructure almost always <a href="https://www.intactcentreclimateadaptation.ca/rising-seas-and-shifting-sands-combining-natural-and-grey-infrastructure-to-protect-canadas-eastern-and-western-coastal-communities/">increases erosion</a> in adjacent areas, is expensive to maintain and degrades over time. Engineers predict that repairs, including <a href="https://www2.gnb.ca/content/dam/gnb/Departments/trans/Chignecto/chignecto-isthmus-project-report-e.pdf">raising the dykes along the Chignecto Isthmus</a> between New Brunswick and Nova Scotia, will cost between $189-300 million. </p>
<p>With such an astronomical price tag, even smaller projects are simply not an option for many municipalities or individual landowners.</p>
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Read more:
<a href="https://theconversation.com/coastal-erosion-is-unstoppable-so-how-do-we-live-with-it-186365">Coastal erosion is unstoppable – so how do we live with it?</a>
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<p>In the face of such challenges, there are opportunities to adapt engineering and protective infrastructure to be more sustainable by integrating natural elements and processes.</p>
<h2>Nature-based solutions</h2>
<p><a href="https://www.transcoastaladaptations.com/nature-based-climate-change-adaptation">Nature-based approaches</a> preserve or reintroduce natural structures and materials into the environment, recognizing and respecting natural systems and their benefits for humans. </p>
<p>Nature-based approaches range from those that are entirely natural to hybrid solutions, which incorporate traditional hard engineering with natural features.</p>
<p>Examples of nature-based solutions <a href="https://static1.squarespace.com/static/5c83d5c63560c33561cc74de/t/61aeca0bf994d4620c5aba87/1638844941547/MRfM_BelcherStMarsh_Case_Study_Final__Dec_05_21_Updated.pdf">include</a> dyke realignment to restore natural water flow and allow saltmarsh reestablishment, wetland and dune restoration, and living shorelines which utilize plants, sand and rock to protect the coast. </p>
<p>Nature-based approaches can involve <a href="https://doi.org/10.1016/j.nbsj.2022.100044">reserving land for natural systems by protecting them from development</a> and making room for the evolution of natural systems; they can also <a href="https://doi.org/10.1016/j.landusepol.2021.105960">involve moving back from the coast, and releasing land back to nature</a>.</p>
<p>Hard infrastructure weakens over time while nature-based solutions grow stronger as plants establish roots, biodiversity increases and natural processes adjust. </p>
<p>Nature-based solutions provide a wide array of benefits. In addition to protecting coastal places from flooding, storm surges and erosion. Nature-based solutions <a href="http://stewardshipcentrebc.ca/PDF_docs/greenshores/Resources/Green%20Shores%202020_%20Impact,%20Value%20and%20Lessons%20Learned_%20Full%20Report_July2020.pdf">prevent shoreline pollution</a>, <a href="https://www.mdpi.com/2071-1050/10/2/523/htm">support biodiversity</a>, can <a href="http://stewardshipcentrebc.ca/PDF_docs/greenshores/Resources/Green%20Shores%202020_%20Impact,%20Value%20and%20Lessons%20Learned_%20Full%20Report_July2020.pdf">increase property value</a> and contribute to overall <a href="https://doi.org/10.3390/su131910950">human well-being</a>. </p>
<p>Incorporating nature-based solutions requires innovation and open-mindedness that may feel intimidating and it is often <a href="https://web.archive.org/web/20220329065340id_/https:/nhess.copernicus.org/preprints/nhess-2022-104/nhess-2022-104.pdf">easier to trust a stone or concrete wall</a> over the energy absorbing power of plants and soil. </p>
<p>As such, <a href="https://doi.org/10.1016/j.nbsj.2022.100044">raising awareness</a> about different nature-based options and being transparent about <a href="https://doi.org/10.1098%2Frstb.2019.0120">costs and benefits</a> can help build confidence in nature-based solutions. </p>
<p>Successful nature-based solutions also require place-based <a href="https://web.archive.org/web/20220329065340id_/https:/nhess.copernicus.org/preprints/nhess-2022-104/nhess-2022-104.pdf">collaboration and knowledge sharing</a> between impacted peoples, engineers, scientists and decision-makers that consider social
and ecological interests. </p>
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Read more:
<a href="https://theconversation.com/st-lawrence-shoreline-erosion-we-must-work-with-not-against-nature-184721">St. Lawrence shoreline erosion: We must work with, not against, nature</a>
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<p><a href="https://royalsociety.org/topics-policy/projects/biodiversity/nature-based-solutions/">Nature-based solutions cannot be prescribed as top-down interventions</a>. Every situation is unique, and many people with diverse knowledge and perspectives should come together to decide how specific nature-based approaches can meet various infrastructure, ecological and social needs as well as increase flood resilience.</p>
<h2>What now?</h2>
<p>For natural resource and permitting agencies, as well as many property owners, the tradition of building hard armoured shorelines remains deeply ingrained. Current guidance documents, policies and habits were built for hard infrastructure. In some cases, <a href="https://doi.org/10.3390/su11236735">bureaucratic decision-making structures</a> move slower than hazards from flooding. </p>
<p>In other cases, including lack of or delayed implementation of legislation, such as <a href="https://www.halifaxexaminer.ca/government/province-house/houston-government-once-again-delays-implementation-of-coastal-protection-act/">the Coastal Protection Act</a> and regulations in Nova Scotia, <a href="https://ecologyandsociety.org/vol28/iss2/art25/">political interests</a> hinder planning actions that would limit hard infrastructure and development along the coast.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/iXkrS1u5fl8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">An overview of the problems of erosion facing many communities across Canada, particularly in the North. Produced by the CBC.</span></figcaption>
</figure>
<p><a href="https://climatechoices.ca/wp-content/uploads/2021/09/Infrastructure-English-FINAL-Sep29.pdf?utm_source=vancouver%20is%20awesome&utm_campaign=vancouver%20is%20awesome%3A%20outbound&utm_medium=referral">Many Canadians</a> are buying homes in areas with high flood risk. The infrastructure they rely upon is <a href="https://changingclimate.ca/national-issues/chapter/2-0/">aging</a> and requires adaptation. Infrastructure supporting <a href="https://highways.dot.gov/public-roads/autumn-2021/02">bridges, roads</a> and <a href="https://doi.org/10.1016/j.nbsj.2022.100013">rail lines</a> needs to be upgraded or removed, providing opportunities to incorporate nature-based solutions.</p>
<h2>Hope for the future</h2>
<p>As we look towards what can feel like an ominous future, there are many resources for individuals or organisations seeking additional information and guidance about nature-based solutions. <a href="https://www.transcoastaladaptations.com/">TransCoastal Adaptations: Centre for Nature-based Solutions</a> is a practitioner, academic and government partnership in Nova Scotia focused on restoration, managed realignment and climate change adaptation. </p>
<p>Privately owned companies, also in Nova Scotia, <a href="https://helpingnatureheal.com/">Helping Heal Nature</a> and <a href="https://www.cbwes.com/">CB Wetlands and Environmental Specialists</a>, focus on ecological restoration, living shorelines and community stewardship and education. Nation-wide <a href="https://coastalzonecanada.org/nbcs/">communities of practice</a> exist to build capacity for natural and nature-based approaches.</p>
<p>As more people learn about nature-based solutions, there will be more opportunities to incorporate natural processes into coastal protection. We know the stakes, and we have nature-based solutions at hand. It’s time to give dirt and plants a chance.</p><img src="https://counter.theconversation.com/content/217353/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Keahna Margeson receives funding from the Ocean Frontier Institute Ocean Graduate Excellence Network, Canada First Research Excellence Fund, Social Sciences and Humanities Research Council, and National Research Council Canada. </span></em></p>As seas rise, it is clear that traditional coastal defence approaches are unable to keep pace. Nature-based solutions offer considerable potential to protect coasts, people and biodiversity.Keahna Margeson, IDPhD Student, School for Resource and Environmental Studies, Dalhousie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2114312023-08-30T20:36:24Z2023-08-30T20:36:24ZWe studied more than 1,500 coastal ecosystems - they will drown if we let the world warm above 2°C<figure><img src="https://images.theconversation.com/files/545179/original/file-20230829-15-v3if80.jpeg?ixlib=rb-1.1.0&rect=46%2C20%2C3368%2C2826&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Simon Albert</span></span></figcaption></figure><p>Much of the world’s natural coastline is protected by living habitats, most notably mangroves in warmer waters and tidal marshes closer to the poles. These ecosystems support fisheries and wildlife, absorb the impact of crashing waves and clean up pollutants. But these vital services are threatened by global warming and rising sea levels. </p>
<p>Recent research has shown wetlands can respond to sea level rise by building up their root systems, <a href="https://theconversation.com/rising-seas-allow-coastal-wetlands-to-store-more-carbon-113020">pulling carbon dioxide from the atmosphere in the process</a>. Growing recognition of the potential for this “blue” carbon sequestration is driving mangrove and tidal marsh restoration projects. </p>
<p>While the resilience of these ecosystems is impressive, it is not without limits. Defining the upper limits to mangrove and marsh resilience under accelerating sea level rise is a topic of great interest and considerable debate. </p>
<p>Our new research, <a href="https://www.nature.com/articles/s41586-023-06448-z">published today in the journal Nature</a>, analyses the vulnerability and exposure of mangroves, marshes and coral islands to sea level rise. The results underscore the critical importance of keeping global warming within 2 degrees of the pre-industrial baseline. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542967/original/file-20230816-19-44orpq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo showing uprooted trees in tropical waters of the Solomon Islands." src="https://images.theconversation.com/files/542967/original/file-20230816-19-44orpq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542967/original/file-20230816-19-44orpq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=215&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542967/original/file-20230816-19-44orpq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=215&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542967/original/file-20230816-19-44orpq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=215&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542967/original/file-20230816-19-44orpq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=271&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542967/original/file-20230816-19-44orpq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=271&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542967/original/file-20230816-19-44orpq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=271&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Coral islands are contracting, causing habitat loss in the Solomon Islands.</span>
<span class="attribution"><span class="source">Simon Albert</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/not-waving-drowning-why-keeping-warming-under-1-5-is-a-life-or-death-matter-for-tidal-marshes-187540">Not waving, drowning: why keeping warming under 1.5℃ is a life-or-death matter for tidal marshes</a>
</strong>
</em>
</p>
<hr>
<h2>What we did</h2>
<p>We pulled together all the available evidence on how mangroves, tidal marshes and coral islands respond to sea level rise. That included: </p>
<ul>
<li><p>delving into the geological record to study how coastal systems responded to past sea level rise, following the last Ice Age</p></li>
<li><p>tapping into a global network of <a href="https://www.usgs.gov/centers/eesc/science/surface-elevation-table">survey benchmarks</a> in mangroves and tidal marshes</p></li>
<li><p>analysing satellite imagery for changes in the extent of wetlands and coral islands at varying rates of sea level rise.</p></li>
</ul>
<p>Altogether, our international team assessed 190 mangroves, 477 tidal marshes and 872 coral reef islands around the world. </p>
<p>We then used computer modelling to work out how much these coastal ecosystems would be exposed to rapid sea level rise under projected warming scenarios. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545438/original/file-20230830-15-1g4pn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of the eroding wetland at Towra Point in Sydney, showing the stumps and exposed roots of trees washed up on the beach" src="https://images.theconversation.com/files/545438/original/file-20230830-15-1g4pn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545438/original/file-20230830-15-1g4pn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545438/original/file-20230830-15-1g4pn5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545438/original/file-20230830-15-1g4pn5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545438/original/file-20230830-15-1g4pn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545438/original/file-20230830-15-1g4pn5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545438/original/file-20230830-15-1g4pn5.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">Eroding wetland at Towra Point in Sydney.</span>
<span class="attribution"><span class="source">Neil Saintilan</span></span>
</figcaption>
</figure>
<h2>What we found</h2>
<p>Mangroves, tidal marshes and coral islands can cope with low rates of sea-level rise. They remain stable and healthy. </p>
<p>We found most tidal marshes and mangroves are keeping pace with current rates of sea level rise, around 2–4mm per year. Coral islands also appear stable under these conditions. </p>
<p>In some locations, land is sinking, so the relative rate of sea level rise is greater. It may be double this 2–4mm figure or more, comparable to rates expected under future climate change. In these situations, we found <a href="https://theconversation.com/not-waving-drowning-why-keeping-warming-under-1-5-is-a-life-or-death-matter-for-tidal-marshes-187540">marshes failing to keep up</a> with sea level rise. They are slowly drowning and in some cases, breaking up. What’s more, these are the same rates of sea level rise under which marshes and mangrove drown in the geological record.</p>
<p>These cases give us a glimpse of the future in a warming world.</p>
<p>So if the rate of sea level rise doubles to 7 or 8 millimetres a year, it becomes “very likely” (90% probability) mangroves and tidal marshes will no longer keep pace, and “likely” (about 67% probability) coral islands will undergo rapid changes. These rates will be reached when the 2.0°C warming threshold is exceeded. </p>
<p>Even at the lower rates of sea level rise we would have between 1.5°C and 2.0°C of warming (4 or 5mm a year), extensive loss of mangrove and tidal marsh is likely. </p>
<p>Tidal marshes are less exposed to these rates of sea level rise than mangroves because they occur in regions where the land is rising, reducing the relative rate of sea level rise.</p>
<iframe title="" aria-label="Table" id="datawrapper-chart-X0tLs" src="https://datawrapper.dwcdn.net/X0tLs/1/" scrolling="no" frameborder="0" style="width: 0; min-width: 100% !important; border: none;" height="340" data-external="1" width="100%"></iframe>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/rising-seas-threaten-to-drown-important-mangrove-forests-unless-we-intervene-49146">Rising seas threaten to drown important mangrove forests, unless we intervene</a>
</strong>
</em>
</p>
<hr>
<h2>Let’s give coastal ecosystems a fighting chance</h2>
<p>We know mangroves and tidal marshes have survived rapid sea level rise before, at rates even higher than those projected under extreme climate change. </p>
<p>They won’t have long enough to build up root systems or trap sediment in order to stay in place, so they will seek higher ground by shifting landward into newly flooded coastal lowlands. </p>
<p>But this time, they will be competing with other land uses and increasingly trapped behind coastal levees and hard barriers such as roads and buildings. </p>
<p>If the global temperature rise is limited to 2°C, coastal ecosystems have a fighting chance. But if this threshold is exceeded, they will need more help. </p>
<p>Intervention is needed to enable the retreat of mangroves and tidal marshes across our coastal landscapes. There is a role for governments in designating retreat pathways, controlling coastal development, and expanding coastal nature reserves into higher ground. </p>
<p>The future of the world’s living coastlines is in our hands. If we work to restore mangroves and tidal marshes to their former extent, they can help us tackle climate change. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-can-drive-social-tipping-points-for-better-or-for-worse-210641">Climate change can drive social tipping points – for better or for worse</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/211431/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Neil Saintilan receives funding from the Australian Research Council, the National Environmental Science Program, and the Alexander Von Humboldt Foundation.</span></em></p>Rising seas are pushing coastal ecosystems to the limit of endurance. Now international research reveals a “tipping point” will be reached if we allow more than 2 degrees of global warming.Neil Saintilan, Professor, School of Natural Sciences, Macquarie 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/2009722023-03-01T20:56:15Z2023-03-01T20:56:15ZThe Antarctic ice sheet is melting. And this is bad news for humanity<figure><img src="https://images.theconversation.com/files/513016/original/file-20230301-26-m2bts0.jpg?ixlib=rb-1.1.0&rect=23%2C29%2C974%2C636&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">If left unchecked, the complete melting of the West Antarctic ice sheet would cause a global sea level increase of 3.3 metres in the distant future.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Ottawa’s famous <a href="https://ncc-ccn.gc.ca/places/rideau-canal-skateway">Rideau Canal</a>, which turns into the world’s largest ice rink every winter, is too thin to open this winter.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/512907/original/file-20230301-14-3mtp2i.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Antarctic sea ice concentration" src="https://images.theconversation.com/files/512907/original/file-20230301-14-3mtp2i.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/512907/original/file-20230301-14-3mtp2i.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=550&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512907/original/file-20230301-14-3mtp2i.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=550&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512907/original/file-20230301-14-3mtp2i.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=550&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512907/original/file-20230301-14-3mtp2i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=691&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512907/original/file-20230301-14-3mtp2i.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=691&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512907/original/file-20230301-14-3mtp2i.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=691&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Antarctic sea ice concentration reached a record low on Feb. 13. The orange line represents the median sea ice extent for that day considering the period 1981-2010.</span>
<span class="attribution"><span class="source">(National Snow and Ice Data Center, University of Colorado, Boulder)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Thousands of kilometres to the south, we can see a similar issue on a much larger scale in the Antarctic, where the sea ice is also struggling to form. The Antarctic sea ice extent — region with at least 15 per cent sea ice cover — reached a <a href="http://nsidc.org/arcticseaicenews/2023/02/antarctic-sea-ice-extent-sets-a-new-record-low/">record low</a> on Feb. 13. </p>
<p>While the mass of the Antarctic ice sheet has been decreasing for a long time, the Antarctic sea ice extent has been strongly decreasing since 2016.</p>
<p>If left unchecked, the <a href="https://thwaitesglacier.org/news/runaway-west-antarctic-ice-retreat-can-be-slowed">complete melting of the West Antarctic ice sheet</a> would cause a global sea level increase of 3.3 metres in the distant future.</p>
<h2>The white continent</h2>
<p>The ice-covered continent of <a href="https://www.nsf.gov/geo/opp/antarct/science/icesheet.jsp">Antarctica</a>, surrounded by the Southern Ocean, holds 90 per cent of the world’s ice. </p>
<p>This mass of ice that forms the ice cover, or ice sheet, over land has resulted from the accumulation and compaction of the snow over thousands of years. And when it extends over the sea, it forms an ice shelf.</p>
<p>The Antarctic ice sheet comprises the West Antarctic ice sheet and the East Antarctic ice sheet. Most of the West Antarctic ice sheet is below the sea level. Around the Antarctic, the extent of the sea ice — which forms from ocean water — increases in winter and decreases in summer.</p>
<h2>The Antarctic warms faster</h2>
<p>The Antarctic is not free from climate change. On the contrary, the rise in temperatures at high latitudes is much stronger than the rise in the global mean temperature. This phenomenon is known as <a href="https://www.realclimate.org/index.php/archives/2006/01/polar-amplification/">polar amplification</a>.</p>
<p>This phenomenon can be explained by the <a href="https://www.britannica.com/science/global-warming/Feedback-mechanisms-and-climate-sensitivity#ref979387">ice-albedo feedback</a>. The increase in the near-surface temperature contributes to the melting of the ice, which contributes to the increase in the temperature. Why? Because the <a href="https://www.npolar.no/en/fact/albedo/">albedo</a> — the fraction of solar energy that is reflected by a surface — of the ocean and of the ground underneath is lower than that of the ice.</p>
<p>Over the last four decades, climate change has caused a <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf">decrease in the average extent of sea ice</a> in the Arctic, but not in the Antarctic. The reason for this statistically insignificant decrease in the average Antarctic sea ice extent is the regional tendencies — the sea ice extent has increased in some regions and decreased in others — compensate for each other. Another reason is the strong <a href="https://doi.org/10.1007/s00382-020-05296-1">internal variability.</a></p>
<figure class="align-center ">
<img alt="Ice extent in the Antarctic" src="https://images.theconversation.com/files/512993/original/file-20230301-23-udectf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512993/original/file-20230301-23-udectf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=325&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512993/original/file-20230301-23-udectf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=325&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512993/original/file-20230301-23-udectf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=325&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512993/original/file-20230301-23-udectf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=408&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512993/original/file-20230301-23-udectf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=408&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512993/original/file-20230301-23-udectf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=408&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">After decreasing the sea ice extent in the Arctic for decades, climate change is now visibly impacting the Antarctic sea ice too.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>However, the <a href="http://nsidc.org/arcticseaicenews/2023/02/antarctic-sea-ice-extent-sets-a-new-record-low/">Antarctic sea ice extent has decreased a lot since 2016</a>. The decrease in the surface of the sea ice cover contributes to the increase in the temperature, but not to sea level rise. This is because the <a href="http://www.ces.fau.edu/nasa/impacts/melting-ice/sea-ice.php">volume of water that the ice displaces</a> when it forms is the same as it adds to the ocean when it melts. As for the <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/factsheets/IPCC_AR6_WGI_Regional_Fact_Sheet_Polar_regions.pdf">Antarctic ice sheet</a>, its mass has decreased since at least 1990, with the highest loss rate during the last decade.</p>
<p>In its <a href="https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/#faq-9-1/">Sixth Assessment Report</a>, the Intergovernmental Panel on Climate Change (IPCC) found that, in the Antarctic, temperature will continue to increase and the mass of the ice sheet will continue to decrease. The growth of this ice sheet is much slower than its retreat, which means that, if it continues to melt during this century, this melting will not be reversible at a human time scale.</p>
<p>The degree of confidence in the climate projections surrounding the Antarctic sea ice is weak, as the climate model simulations do not accurately capture its observed evolution. And so, we cannot make any definitive conclusions about it.</p>
<h2>The consequences of the collapsing ice sheet</h2>
<p>The <a href="https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/#faq-9-1/">sustained melting of the West Antarctic ice sheet</a> could indicate that an unstable retreat (which reinforces itself) is underway or imminent. However, there is high uncertainty about this phenomenon.</p>
<p>The mechanism that would explain this unstable retreat 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>If the bed, where the ice sheet lies, slopes down towards the interior, it destabilizes the position of the grounding line — zone where this ice sheet starts to float. The thinning of the ice shelf causes this grounding line to retreat, which leads to an influx of ice from the ice sheet to the sea. This, subsequently, causes the thinning of the ice shelf and so on and so forth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/512909/original/file-20230301-24-3ynzq1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing the Marine Ice Sheet Instability (MSI) process" src="https://images.theconversation.com/files/512909/original/file-20230301-24-3ynzq1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512909/original/file-20230301-24-3ynzq1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=252&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512909/original/file-20230301-24-3ynzq1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=252&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512909/original/file-20230301-24-3ynzq1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=252&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512909/original/file-20230301-24-3ynzq1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=317&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512909/original/file-20230301-24-3ynzq1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=317&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512909/original/file-20230301-24-3ynzq1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=317&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Schema showing the Marine Ice Sheet Instability (MSI) process. The blue arrows indicate the retreat of the grounding line, and the white arrows indicate the ice flux.</span>
<span class="attribution"><span class="source">(Pattyn, F. The paradigm shift in Antarctic ice sheet modelling. Nat Commun 9, 2728 (2018))</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>At present, the world is <a href="https://www.unep.org/resources/emissions-gap-report-2022">heading towards a warming of 2.8 C</a> by the end of this century. A sustained warming of about 2 C to 3 C would be sufficient <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/factsheets/IPCC_AR6_WGI_Regional_Fact_Sheet_Polar_regions.pdf">to make this ice sheet almost completely disappear</a>, but this phenomenon would take thousands of years.</p>
<p>The bottom line is that the melting of the Antarctic ice sheet contributes to and will continue to contribute to sea level rise for a long time, which will test the adaptive capacity of humanity.</p>
<p>The sea level increase by 2100 will particularly affect the <a href="https://doi.org/10.1038/s41467-021-23810-9">tropical countries</a>. And so, what happens in the Antarctic will definitely not stay in the Antarctic.</p><img src="https://counter.theconversation.com/content/200972/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marta Moreno Ibáñez has received an excellence scholarship from the Trottier Family Foundation.</span></em></p>The melting of the Antarctic ice sheet will contribute for a long time to sea level rise, which will test humanity’s capacity to adapt.Marta Moreno Ibáñez, PhD candidate in Earth and atmospheric sciences, Université du Québec à Montréal (UQAM)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1966552022-12-19T20:56:35Z2022-12-19T20:56:35Z5,700 years of sea-level change in Micronesia hint at humans arriving much earlier than we thought<figure><img src="https://images.theconversation.com/files/501265/original/file-20221215-13-q12vwv.jpg?ixlib=rb-1.1.0&rect=72%2C114%2C3953%2C2565&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mangrove forests on Pohnpei are archives of sea-level change.</span> <span class="attribution"><span class="source">Juliet Sefton</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Sea levels in Micronesia rose much faster over the past 5,000 years than previously thought, according to our new study <a href="https://www.pnas.org/cgi/doi/10.1073/pnas.2210863119">published today in Proceedings of the National Academy of Sciences</a>.</p>
<p>This sea-level rise is shown by the accumulation of mangrove sediments on the islands of Pohnpei and Kosrae. The finding may change how we think about when people migrated into Remote Oceania, and where they might have voyaged from.</p>
<h2>Formidable voyagers</h2>
<p>While recent decades saw <a href="https://www.science.org/doi/10.1126/science.abm6536">significant advancements</a> in linguistic, bio-anthropological and archaeological research in the region, the exact pattern and timing of human settlement of Remote Oceania is still debated.</p>
<p>Humans began migration into Remote Oceania – the area of the “open” Pacific Ocean east of New Guinea and the Philippines – some 3,300–3,500 years ago. This migration required formidable long-distance ocean voyaging of the likes never seen before in human history.</p>
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Read more:
<a href="https://theconversation.com/what-wind-currents-and-geography-tell-us-about-how-people-first-settled-oceania-67410">What wind, currents and geography tell us about how people first settled Oceania</a>
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<hr>
<p>The region of Micronesia extends many thousands of kilometres and contains thousands of low-lying atolls. Many of these atolls formed roughly 2,500 years ago when the sea level in the region <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL049163">stabilised close to where it is today</a>.</p>
<p>Before that, the sea level might have been up to two metres higher than at present. People could only settle these atolls successfully once sea levels had lowered and stabilised.</p>
<p>But there are also older and higher volcanic islands in Micronesia. Across Remote Oceania, these higher islands were more desirable for settlement than low-lying atolls because they have more reliable freshwater sources, more developed soils for agriculture, and are less vulnerable to storm surges.</p>
<p>We looked at the published ages of settlement across the western part of Remote Oceania and found that high islands tend to show earlier ages of settlement compared to atolls, which is what we would expect. But we don’t see this pattern in Micronesia: the high islands of Pohnpei and Kosrae show settlement ages about 1,000 years later than other similar islands. Why?</p>
<h2>Mangrove clues</h2>
<p>Deep within the mangrove forests of Pohnpei and Kosrae, <a href="https://www.scirp.org/journal/paperinformation.aspx?paperid=53298">previous</a> <a href="https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/81/7/1895/6917/Paludal-Stratigraphy-of-Truk-Ponape-and-Kusaie">researchers found</a> mangrove sediments up to five metres deep. The only explanation for such deep mangrove sediments is sustained sea-level rise.</p>
<p>Mangroves live at the coast, between low tide and high tide. Therefore, as sea level rises, organic carbon and sediments accumulate beneath the mangrove forests, <a href="https://theconversation.com/rising-seas-allow-coastal-wetlands-to-store-more-carbon-113020">creating deep soils</a>.</p>
<p>We visited the mangroves on Pohnpei and Kosrae and collected sediment cores to find out how old the sediments beneath them were. Our new data, as well as previous works, show that the oldest mangrove sediment is about 5,700 years old.</p>
<p>From this, we calculated that over the past 5,700 years, sea level rose by about four metres. The most likely cause for this rise is that the islands are sinking: the land is going down relative to the sea surface. </p>
<p>In our new study, we suggest this sea-level rise obscured the archaeological record on Pohnpei and Kosrae. Consequently, evidence of earlier settlement – in line with other high islands – may be submerged today.</p>
<p>It is possible that people settled this region of Micronesia much earlier than previously thought, which also raises questions about whether people voyaged from the west or from the south to reach these islands. </p>
<h2>A testament to rising seas</h2>
<p>The <a href="https://whc.unesco.org/en/list/1503/">UNESCO World Heritage Site of Nan Madol</a> on Pohnpei may also stand as a testament to rising seas. Nan Madol is an impressive array of abandoned megalithic buildings constructed from dark basalt columns and crushed coral.</p>
<p>This site has been dubbed the “<a href="https://www.cambridge.org/core/journals/quaternary-research/article/earliest-direct-evidence-of-monument-building-at-the-archaeological-site-of-nan-madol-pohnpei-micronesia-identified-using-230thu-coral-dating-and-geochemical-sourcing-of-megalithic-architectural-stone/0338E86D312973BA0B32D56A5D297FAF">Venice of the Pacific</a>” because of the characteristic network of waterways around the buildings, resembling canals and islets.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial view of stone constructions topped with lush jungle greenery, with brown canal-like waterways around them" src="https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nan Madol is characterised by waterways snaking around ancient megalithic buildings.</span>
<span class="attribution"><span class="source">KKvintage/Shutterstock</span></span>
</figcaption>
</figure>
<p>Our record of sea-level rise from the mangrove sediment shows that <a href="https://www.cambridge.org/core/journals/quaternary-research/article/earliest-direct-evidence-of-monument-building-at-the-archaeological-site-of-nan-madol-pohnpei-micronesia-identified-using-230thu-coral-dating-and-geochemical-sourcing-of-megalithic-architectural-stone/0338E86D312973BA0B32D56A5D297FAF">when Nan Madol was constructed</a> (around 1180 to 1200 CE), the sea level was nearly one metre lower than it is today.</p>
<p>We suggest that it is unlikely Nan Madol was built with canals and islands in mind. Rather, the canals and islets are a result of sea-level rise over nearly 1,000 years.</p>
<p>Much like island nations today, large stone walls may have been constructed to protect the site from waves that were slowly encroaching higher and higher. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/islands-lost-to-the-waves-how-rising-seas-washed-away-part-of-micronesias-19th-century-history-82981">Islands lost to the waves: how rising seas washed away part of Micronesia's 19th-century history</a>
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<img src="https://counter.theconversation.com/content/196655/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Juliet Sefton received funding from the US National Science Foundation (award number OCE-1831382) and was hosted by Tufts University while conducting this research. Juliet now works at Monash University. </span></em></p><p class="fine-print"><em><span>Andrew Kemp receives funding from the US National Science Foundation (award OCE-1831382). </span></em></p><p class="fine-print"><em><span>Mark D. McCoy has received funding from the US National Science Foundation, New Zealand's Marsden Fund, and National Geographic.</span></em></p>A new analysis of deep soil sediments accumulated in the mangroves of Pohnpei and Kosrae islands reveals a potentially different history of human arrival in this oceanic region.Juliet Sefton, Assistant Lecturer, Monash UniversityAndrew Kemp, Associate professor, Tufts UniversityMark D. McCoy, Associate professor, Southern Methodist UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1947282022-11-16T23:07:51Z2022-11-16T23:07:51ZAn entire Pacific country will upload itself to the metaverse. It’s a desperate plan – with a hidden message<figure><img src="https://images.theconversation.com/files/495556/original/file-20221116-21-2v3psz.jpg?ixlib=rb-1.1.0&rect=100%2C100%2C5505%2C3891&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What's the message between the lines of Tuvalu's proposal to move to the metaverse?</span> <span class="attribution"><a class="source" href="https://unsplash.com/s/photos/message-in-the-bottle">Scott Van Hoy/Unsplash</a>, <a class="license" href="http://artlibre.org/licence/lal/en">FAL</a></span></figcaption></figure><p>The Pacific nation of Tuvalu is planning to create a version of itself in the metaverse, as a response to the existential threat of rising sea levels. Tuvalu’s minister for justice, communication and foreign affairs, Simon Kofe, made the announcement via a chilling digital address to leaders at COP27. </p>
<p>He said the plan, which accounts for the “worst case scenario”, involves creating a <a href="https://theconversation.com/au/topics/digital-twin-89034">digital twin</a> of Tuvalu in the metaverse in order to replicate its beautiful islands and preserve its rich culture:</p>
<blockquote>
<p>The tragedy of this outcome cannot be overstated […] Tuvalu could be the first country in the world to exist solely in cyberspace – but if global warming continues unchecked, it won’t be the last.</p>
</blockquote>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/sJIlrAdky4Q?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Tuvalu turns to metaverse as rising seas threaten existence, 16 Nov 2022.</span></figcaption>
</figure>
<p>The idea is that the metaverse might allow Tuvalu to “fully function as a sovereign state” as its people are forced to live somewhere else. </p>
<p>There are two stories here. One is of a small island nation in the Pacific facing an existential threat and looking to preserve its nationhood through technology. </p>
<p>The other is that by far the preferred future for Tuvalu would be to avoid the worst effects of climate change and preserve itself as a terrestrial nation. In which case, this may be its way of getting the world’s attention. </p>
<h2>What is a metaverse nation?</h2>
<p>The <a href="https://theconversation.com/what-is-the-metaverse-and-what-can-we-do-there-179200">metaverse</a> represents a burgeoning future in which augmented and virtual reality become part of everyday living. There are many visions of what the metaverse might look like, with the most well-known coming from Meta (previously Facebook) CEO Mark Zuckerberg.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-the-metaverse-and-what-can-we-do-there-179200">What is the metaverse, and what can we do there?</a>
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<p>What most of these visions have in common is the idea that the metaverse is about interoperable and immersive 3D worlds. A persistent avatar moves from one virtual world to another, as easily as moving from one room to another in the physical world.</p>
<p>The aim is to obscure the human ability to distinguish between the real and the virtual, for <a href="https://theconversation.com/what-is-the-metaverse-a-high-tech-plan-to-facebookify-the-world-165326">better or for worse</a>.</p>
<p>Kofe implies three aspects of Tuvalu’s nationhood could be recreated in the metaverse:</p>
<ol>
<li><p>territory – the recreation of the natural beauty of Tuvalu, which could be interacted with in different ways</p></li>
<li><p>culture – the ability for Tuvaluan people to interact with one another in ways that preserve their shared language, norms and customs, wherever they may be</p></li>
<li><p>sovereignty – if there were to be a loss of terrestrial land over which the government of Tuvalu has sovereignty (a tragedy beyond imagining, but which they have begun to imagine) then could they have sovereignty over virtual land instead?</p></li>
</ol>
<h2>Could it be done?</h2>
<p>In the case that Tuvalu’s proposal is, in fact, a literal one and not just symbolic of the dangers of climate change, what might it look like?</p>
<p>Technologically, it’s already easy enough to create beautiful, immersive and richly rendered recreations of Tuvalu’s territory. Moreover, thousands of different online communities and 3D worlds (such as <a href="https://secondlife.com/">Second Life</a>) demonstrate it’s possible to have entirely virtual interactive spaces that can maintain their own culture.</p>
<p>The idea of combining these technological capabilities with features of governance for a “<a href="https://theconversation.com/what-are-digital-twins-a-pair-of-computer-modeling-experts-explain-181829">digital twin</a>” of Tuvalu is feasible. </p>
<p>There have been prior experiments of governments taking location-based functions and creating virtual analogues of them. For example, Estonia’s <a href="https://en.wikipedia.org/wiki/E-Residency_of_Estonia">e-residency</a> is an online-only form of residency non-Estonians can obtain to access services such as company registration. Another example is countries setting up virtual embassies on the <a href="https://www.learntechlib.org/p/178165/">online platform Second Life</a>.</p>
<p>Yet there are significant technological and social challenges in bringing together and digitising the elements that define an entire nation. </p>
<p>Tuvalu has only about 12,000 citizens, but having even this many people interact in real time in an immersive virtual world is a technical challenge. There are <a href="https://www.matthewball.vc/all/networkingmetaverse">issues of bandwidth</a>, computing power, and the fact that many users have an aversion to headsets or suffer nausea.</p>
<p>Nobody has yet demonstrated that nation-states can be successfully translated to the virtual world. Even if they could be, others argue the digital world makes <a href="http://thestack.org/">nation-states redundant</a>.</p>
<p>Tuvalu’s proposal to create its digital twin in the metaverse is a message in a bottle – a desperate response to a tragic situation. Yet there is a coded message here too, for others who might consider retreat to the virtual as a response to loss from climate change.</p>
<h2>The metaverse is no refuge</h2>
<p>The metaverse is built on the physical infrastructure of servers, data centres, network routers, devices and head-mounted displays. All of this tech has a hidden carbon footprint and requires physical maintenance and energy. <a href="https://theconversation.com/the-internet-consumes-extraordinary-amounts-of-energy-heres-how-we-can-make-it-more-sustainable-160639">Research</a> published in Nature predicts the internet will consume about 20% of the world’s electricity by 2025. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-internet-consumes-extraordinary-amounts-of-energy-heres-how-we-can-make-it-more-sustainable-160639">The internet consumes extraordinary amounts of energy. Here's how we can make it more sustainable</a>
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<p>The idea of the <em>metaverse nation</em> as a response to climate change is exactly the kind of thinking that got us here. The language that gets adopted around new technologies – such as “cloud computing”, “virtual reality” and “metaverse” – comes across as both clean and green. </p>
<p>Such terms are laden with “<a href="https://www.publicaffairsbooks.com/titles/evgeny-morozov/to-save-everything-click-here/9781610393706/">technological solutionism</a>” and “<a href="https://eprints.qut.edu.au/203186/">greenwashing</a>”. They hide the fact that technological responses to climate change often <a href="https://www.sciencedirect.com/science/article/abs/pii/S0921800905001084?via%3Dihub">exacerbate the problem</a> due to how energy and resource intensive they are.</p>
<h2>So where does that leave Tuvalu?</h2>
<p>Kofe is well aware the metaverse is not an answer to Tuvalu’s problems. He explicitly states we need to focus on reducing the impacts of climate change through initiatives such as a <a href="https://www.theguardian.com/environment/2022/nov/08/tuvalu-first-to-call-for-fossil-fuel-non-proliferation-treaty-at-cop27">fossil-fuel non-proliferation treaty</a>. </p>
<p>His video about Tuvalu moving to the metaverse is hugely successful as a provocation. It got worldwide press – just like his <a href="https://youtu.be/jBBsv0QyscE">moving plea</a> during COP26 while standing knee-deep in rising water.</p>
<p>Yet Kofe suggests:</p>
<blockquote>
<p>Without a global conscience and a global commitment to our shared wellbeing we may find the rest of the world joining us online as their lands disappear.</p>
</blockquote>
<p>It is dangerous to believe, even implicitly, that moving to the metaverse is a viable response to climate change. The metaverse can certainly assist in keeping heritage and culture alive <a href="https://eprints.qut.edu.au/131407/">as a virtual museum</a> and digital community. But it seems unlikely to work as an ersatz nation-state. </p>
<p>And, either way, it certainly won’t work without all of the land, infrastructure and energy that keeps the internet functioning.</p>
<p>It would be far better for us to direct international attention towards Tuvalu’s other initiatives described in the <a href="https://devpolicy.org/tuvalu-preparing-for-climate-change-in-the-worst-case-scenario-20211110/">same report</a>: </p>
<blockquote>
<p>The project’s first initiative promotes diplomacy based on Tuvaluan values of olaga fakafenua (communal living systems), kaitasi (shared responsibility) and fale-pili (being a good neighbour), in the hope that these values will motivate other nations to understand their shared responsibility to address climate change and sea level rise to achieve global wellbeing.</p>
</blockquote>
<p>The message in a bottle being sent out by Tuvalu is not really about the possibilities of metaverse nations at all. The message is clear: to support communal living systems, to take shared responsibility and to be a good neighbour.</p>
<p>The first of these can’t translate into the virtual world. The second requires us to <a href="https://theconversation.com/ending-the-climate-crisis-has-one-simple-solution-stop-using-fossil-fuels-194489">consume less</a>, and the third requires us to care.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ending-the-climate-crisis-has-one-simple-solution-stop-using-fossil-fuels-194489">Ending the climate crisis has one simple solution: Stop using fossil fuels</a>
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</em>
</p>
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<img src="https://counter.theconversation.com/content/194728/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nick Kelly receives research funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Marcus Foth receives research funding from the Australian Research Council and the Future Food CRC. He is a member of the Queensland Greens.</span></em></p>Rising sea levels due to climate change are already having severe impacts on the nation of Tuvalu. It proposes to build a digital replica of itself in the metaverse. Could it be done?Nick Kelly, Senior Lecturer in Interaction Design, Queensland University of TechnologyMarcus Foth, Professor of Urban Informatics, Queensland University of TechnologyLicensed 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.tag:theconversation.com,2011:article/1855902022-08-29T18:04:43Z2022-08-29T18:04:43ZWhat’s going on with the Greenland ice sheet? It’s losing ice faster than forecast and now irreversibly committed to at least 10 inches of sea level rise<figure><img src="https://images.theconversation.com/files/481620/original/file-20220829-8728-38vmqp.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1415%2C488&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A turbulent melt-river pours a million tons of water a day into a moulin, where it flows down through the ice to ultimately reach the ocean.</span> <span class="attribution"><span class="source">Ted Giffords</span></span></figcaption></figure><p>I’m standing at the edge of the Greenland ice sheet, mesmerized by a mind-blowing scene of natural destruction. A milewide section of glacier front has fractured and is collapsing into the ocean, calving an immense iceberg.</p>
<p>Seracs, giant columns of ice the height of three-story houses, are being tossed around like dice. And the previously submerged portion of this immense block of glacier ice just breached the ocean – a frothing maelstrom flinging ice cubes of several tons high into the air. The resulting tsunami inundates all in its path as it radiates from the glacier’s calving front.</p>
<p>Fortunately, I’m watching from a clifftop a couple of miles away. But even here, I can feel the <a href="https://doi.org/10.1029/2008GL036127">seismic shocks through the ground</a>.</p>
<figure class="align-center ">
<img alt="A large iceberg calves off a glacier." src="https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=344&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=344&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=344&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=433&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=433&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481628/original/file-20220829-8654-38vmqp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=433&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A fast-flowing outlet glacier calves a ‘megaberg’ into Greenland’s Uummannaq Fjord.</span>
<span class="attribution"><span class="source">Alun Hubbard</span></span>
</figcaption>
</figure>
<p>Despite the spectacle, I’m keenly aware that this spells yet more unwelcome news for the world’s low-lying coastlines.</p>
<p>As <a href="https://cage.uit.no/employee/alun-hubbard/">a field glaciologist</a>, I’ve worked on ice sheets for more than 30 years. In that time, I have witnessed some gobsmacking changes. The past few years in particular have been unnerving for the sheer rate and magnitude of change underway. My revered textbooks taught me that ice sheets respond over millennial time scales, but that’s not what we’re seeing today.</p>
<p><a href="https://doi.org/10.1038/s41558-022-01441-2">A study published</a> Aug. 29, 2022, demonstrates – for the first time – that Greenland’s ice sheet is now so out of balance with prevailing Arctic climate that it no longer can sustain its current size. It is irreversibly committed to retreat by at least 59,000 square kilometers (22,780 square miles), an area considerably larger than Denmark, Greenland’s protectorate state.</p>
<p>Even if all the greenhouse gas emissions driving global warming ceased today, we find that Greenland’s ice loss under current temperatures will <a href="https://doi.org/10.1038/s41558-022-01441-2">raise global sea level</a> by at least 10.8 inches (27.4 centimeters). That’s more than current models forecast, and it’s a highly conservative estimate. If every year were like 2012, <a href="https://doi.org/10.5194/tc-10-1147-2016">when Greenland experienced a heat wave</a>, that irreversible commitment to sea level rise would triple. That’s an ominous portent given that these are climate conditions we have already seen, not a hypothetical future scenario.</p>
<p>Our study takes a completely new approach – it is based on observations and glaciological theory rather than sophisticated numerical models. The current generation of <a href="https://doi.org/10.5194/tc-15-5705-2021">coupled climate and ice sheet models used to forecast future sea level rise fail</a> to capture the emerging processes that we see amplifying Greenland’s ice loss.</p>
<h2>How Greenland got to this point</h2>
<p>The <a href="http://nsidc.org/greenland-today/">Greenland ice sheet</a> is a massive, frozen reservoir that resembles an inverted pudding bowl. The ice is in <a href="https://doi.org/10.1002/2013GL058933">constant flux</a>, flowing from the interior – where it is over 1.9 miles (3 kilometers) thick, cold and snowy – to its edges, where the ice melts or calves bergs.</p>
<p>In all, the ice sheet locks up enough fresh water to <a href="https://doi.org/10.1002/2017GL074954">raise global sea level</a> by 24 feet (7.4 meters).</p>
<figure>
<iframe src="https://player.vimeo.com/video/743951647" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">David Attenborough takes us on a virtuoso tour of the Greenland ice sheet.</span></figcaption>
</figure>
<p>Greenland’s <a href="https://doi.org/10.1038/307620a0">terrestrial ice has existed for about 2.6 million years and has expanded and contracted with two dozen or so “ice age” cycles</a> lasting 70,000 or 100,000 years, punctuated by around 10,000-year warm interglacials. Each glacial is driven by <a href="https://climate.nasa.gov/ask-nasa-climate/2949/why-milankovitch-orbital-cycles-cant-explain-earths-current-warming">shifts in Earth’s orbit</a> <a href="https://doi.org/10.1126%2Fscience.194.4270.1121">that modulate</a> how much solar radiation reaches the Earth’s surface. These variations are then reinforced by snow reflectivity, or albedo; atmospheric greenhouse gases; and ocean circulation that redistributes that heat around the planet.</p>
<p>We are currently enjoying an interglacial period – the Holocene. For the past 6,000 years Greenland, like the rest of the planet, has benefited from a mild and stable climate with an ice sheet in equilibrium – until recently. Since 1990, as the atmosphere and ocean have warmed under rapidly increasing greenhouse gas emissions, Greenland’s mass balance has gone into the red. Ice losses due to enhanced melt, rain, ice flow and calving now far exceed the net gain from snow accumulation.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/stm1pBp0rfk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Greenland’s ice mass loss measured by NASA’s Grace satellites.</span></figcaption>
</figure>
<h2>What does the future hold?</h2>
<p>The critical questions are, how fast is Greenland losing its ice, and what does it mean for future sea level rise?</p>
<p>Greenland’s ice loss has been <a href="https://doi.org/10.1002/2017GL074954">contributing about 0.04 inches</a> (1 millimeter) per year to <a href="https://www.ipcc.ch/srocc/chapter/chapter-4-sea-level-rise-and-implications-for-low-lying-islands-coasts-and-communities/">global sea level rise</a> over the past decade.</p>
<p><a href="https://doi.org/10.1126/science.1178176">This net loss is split between surface melt and dynamic processes</a> that accelerate outlet glacier flow and are greatly exacerbated by atmospheric and oceanic warming, respectively. Though complex in its manifestation, the concept is simple: Ice sheets don’t like warm weather or baths, and the heat is on.</p>
<figure class="align-center ">
<img alt="A large area of meltwater pools on the snowy Greenland surface and forms a river and streams." src="https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=334&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=334&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=334&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=420&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=420&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481364/original/file-20220826-11967-4s6t9q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=420&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Meltwater lakes feed rivers that snake across the ice sheet - until they encounter a moulin.</span>
<span class="attribution"><span class="source">Alun Hubbard</span></span>
</figcaption>
</figure>
<p>What the future will bring is trickier to answer.</p>
<p>The models used by the <a href="https://www.ipcc.ch/assessment-report/ar6/">Intergovernmental Panel on Climate Change</a> predict a sea level rise contribution from Greenland of <a href="https://doi.org/10.1029/2020GL091741">around 4 inches (10 centimeters) by 2100</a>, with a worst-case scenario of 6 inches (15 centimeters). </p>
<p>But that prediction is at odds with what field <a href="https://doi.org/10.1002/2017GL074954">scientists are witnessing from the ice sheet itself</a>. </p>
<p>According to our findings, Greenland will lose <a href="https://doi.org/10.1038/s41558-022-01441-2">at least 3.3% of its ice</a>, over 100 trillion metric tons. This loss is already committed – ice that <a href="https://www.usgs.gov/special-topics/water-science-school/science/fundamentals-water-cycle">must melt and calve icebergs</a> to reestablish Greenland’s balance with prevailing climate. </p>
<p>We’re observing many emerging processes that the models don’t account for that increase the ice sheet’s vulnerability. For example:</p>
<ul>
<li><p>Increased rain is <a href="https://doi.org/10.1038/ngeo2482">accelerating surface melt and ice flow</a>.</p></li>
<li><p>Large tracts of the ice surface are undergoing <a href="https://doi.org/10.1002/2017GL075958">bio-albedo darkening</a>, which <a href="https://doi.org/10.5194/tc-14-309-2020">accelerates surface melt</a>, as well as the impact of snow <a href="https://www.carbonbrief.org/darkening-ice-speeds-up-greenland-melt-new-research-suggests/">melting and refreezing</a> at the surface. These darker surfaces absorb more solar radiation, driving yet more melt.</p></li>
</ul>
<figure class="align-center ">
<img alt="Weather stations sit atop wet snow in Greenland" src="https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481370/original/file-20220826-12-ohkapl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In August 2021, rain fell at the Greenland ice sheet summit for the first time on record. Weather stations across Greenland captured rapid ice melt.</span>
<span class="attribution"><a class="source" href="https://www.esa.int/ESA_Multimedia/Images/2022/06/Weather_station_high_on_the_Greenland_ice_sheet">European Space Agency</a></span>
</figcaption>
</figure>
<ul>
<li><p>Warm, subtropical-originating <a href="https://doi.org/10.5194/tc-8-1457-2014">ocean currents are intruding into Greenland’s fjords</a> and rapidly eroding outlet glaciers, undercutting and <a href="https://doi.org/10.1002/2015GL065806">destabilizing their calving fronts</a>.</p></li>
<li><p>Supraglacial lakes and river networks are draining into <a href="https://www.washingtonpost.com/climate-environment/2020/12/23/climate-moulins-greenland/">fractures and moulins</a>, bringing with them vast quantities of latent heat. This “<a href="https://doi.org/10.1029/2010GL044397">cryo-hydraulic warming</a>” within and at the base of the ice sheet softens and thaws the bed, thereby <a href="https://doi.org/10.1002/2013GL058933">accelerating interior ice flow</a> down to the margins.</p></li>
</ul>
<h2>The issue with models</h2>
<p>Part of the problem is that the models used for forecasting are mathematical abstractions that include only processes that are fully understood, quantifiable and deemed important.</p>
<p>Models reduce reality to a set of equations that are solved repeatedly on banks of very fast computers. Anyone into cutting-edge engineering – including me – knows the intrinsic value of models for experimentation and testing of ideas. But they are no substitute for reality and observation. It is apparent that current model forecasts of global sea level rise underestimate its actual threat over the 21st century. Developers are making constant improvements, but it’s tricky, and there’s a dawning realization that the complex models used for long-term sea level forecasting <a href="https://doi.org/10.1016/j.oneear.2020.11.002">are not fit for purpose</a>.</p>
<figure class="align-center ">
<img alt="Several brightly colored research tents dot a landscape with streams and snow on the ice sheet." src="https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=334&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=334&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=334&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=419&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=419&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481605/original/file-20220829-20-7mu3w2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=419&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Author Alun Hubbard’s science camp in the melt zone of the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Alun Hubbard</span></span>
</figcaption>
</figure>
<p>There are also “unknown unknowns” – those processes and feedbacks that we don’t yet realize and that models can never anticipate. They can be understood only by direct observations and literally drilling into the ice. </p>
<p>That’s why, rather than using models, we base our study on <a href="https://doi.org/10.1002/2014RG000470">proven glaciological theory</a> constrained by two decades of actual measurements from weather stations, satellites and ice geophysics.</p>
<h2>It’s not too late</h2>
<p>It’s an understatement that the societal stakes are high, and the risk is tragically real going forward. The consequences of catastrophic coastal flooding as sea level rises are still unimaginable to the majority of the billion or so people who live in low-lying coastal zones of the planet.</p>
<figure class="align-center ">
<img alt="A large sailing ship with an even larger iceberg behind it and a glacier in the distance." src="https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481365/original/file-20220826-11332-ij15fr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A large tabular iceberg that calved off Store Glacier within Uummannaq Fjord.</span>
<span class="attribution"><span class="source">Alun Hubbard</span></span>
</figcaption>
</figure>
<p>Personally, I remain hopeful that we can get on track. I don’t believe we’ve passed any doom-laden tipping point that irreversibly floods the planet’s coastlines. Of what I understand of the ice sheet and the insight <a href="https://www.nature.com/articles/s41558-022-01441-2">our new study</a> brings, it’s not too late to act. </p>
<p>But fossil fuels and emissions must be curtailed now, because time is short and the water rises – faster than forecast.</p><img src="https://counter.theconversation.com/content/185590/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alun Hubbard is also affiliated with Oulun yliopisto - The University of Oulu, Finland, Arctic Basecamp & La Venta Explorazioni.</span></em></p>A field glaciologist explains the changes scientists are now seeing.Alun Hubbard, Professor of Glaciology, Arctic Five Chair, University of TromsøLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1788282022-06-07T12:31:51Z2022-06-07T12:31:51ZIce world: Antarctica’s riskiest glacier is under assault from below and losing its grip<figure><img src="https://images.theconversation.com/files/451768/original/file-20220313-22-7yym4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The front of Thwaites Glacier is a jagged, towering cliff.</span> <span class="attribution"><span class="source">David Vaughan/British Antarctic Survey</span></span></figcaption></figure><p>Flying over Antarctica, it’s hard to see what all the fuss is about. Like a gigantic wedding cake, the frosting of snow on top of the world’s largest ice sheet looks smooth and unblemished, beautiful and perfectly white. Little swirls of snow dunes cover the surface.</p>
<p>But as you approach the edge of the ice sheet, a sense of tremendous underlying power emerges. Cracks appear in the surface, sometimes organized like a washboard, and sometimes a complete chaos of spires and ridges, revealing the pale blue crystalline heart of the ice below.</p>
<p>As the plane flies lower, the scale of these breaks steadily grows. These are not just cracks, but canyons large enough to swallow a jetliner, or spires the size of monuments. Cliffs and tears, rips in the white blanket emerge, indicating a force that can toss city blocks of ice around like so many wrecked cars in a pileup. It’s a twisted, torn, wrenched landscape. A sense of movement also emerges, in a way that no ice-free part of the Earth can convey – the entire landscape is in motion, and seemingly not very happy about it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/451767/original/file-20220313-17-dn1yky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A view across the ice from an airplane showing many fractures." src="https://images.theconversation.com/files/451767/original/file-20220313-17-dn1yky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451767/original/file-20220313-17-dn1yky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451767/original/file-20220313-17-dn1yky.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451767/original/file-20220313-17-dn1yky.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451767/original/file-20220313-17-dn1yky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451767/original/file-20220313-17-dn1yky.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451767/original/file-20220313-17-dn1yky.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">Broken ice where Thwaites Glacier heads out to sea.</span>
<span class="attribution"><span class="source">Ted Scambos</span></span>
</figcaption>
</figure>
<p>Antarctica is a continent comprising several large islands, one of them the size of Australia, all buried under a <a href="https://nsidc.org/cryosphere/sotc/ice_sheets.html">10,000-foot-thick layer of ice</a>. The ice holds enough fresh water to raise sea level by nearly 200 feet.</p>
<p>Its glaciers have always been in motion, but beneath the ice, changes are taking place that are having <a href="https://www.youtube.com/watch?v=uBbgWsR4-aw">profound effects</a> on the future of the ice sheet – and on the future of coastal communities around the world.</p>
<h2>Breaking, thinning, melting, collapsing</h2>
<p>Antarctica is where I work. As a <a href="https://scholar.google.com/citations?user=-9H1Dh0AAAAJ&hl=en">polar scientist</a> I’ve visited most areas of the ice sheet in more than 20 trips to the continent, bringing sensors and weather stations, trekking across glaciers, or measuring the speed, thickness and structure of the ice. </p>
<p>Currently, I’m the U.S. coordinating scientist for a major international research effort on Antarctica’s riskiest glacier – more on that in a moment. I have gingerly crossed crevasses, trodden carefully on hard blue windswept ice, and driven for days over the most monotonous landscape you can imagine.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/451494/original/file-20220311-23-13e04jo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451494/original/file-20220311-23-13e04jo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451494/original/file-20220311-23-13e04jo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451494/original/file-20220311-23-13e04jo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451494/original/file-20220311-23-13e04jo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451494/original/file-20220311-23-13e04jo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451494/original/file-20220311-23-13e04jo.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">Mountains direct the flow of glaciers toward the sea.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/1nW5NPuS6hY">66 North via Unsplash</a></span>
</figcaption>
</figure>
<p>For most of the past few centuries, the ice sheet has been stable, as far as polar science can tell. Our ability to track how much ice flows out each year, and how much snow falls on top, extends back <a href="https://climate.esa.int/en/projects/ice-sheets-antarctic/data/">just a handful of decades</a>, but what we see is an ice sheet that <a href="https://doi.org/10.1073/pnas.1812883116">was nearly in balance as recently as the 1980s</a>.</p>
<p>Early on, changes in the ice happened slowly. Icebergs would break away, but the ice was replaced by new outflow. Total snowfall had not changed much in centuries – this we knew from <a href="https://www.antarcticglaciers.org/glaciers-and-climate/ice-cores/ice-core-basics/">looking at ice cores</a> – and in general the flow of ice and the elevation of the ice sheet seemed so constant that a main goal of early ice research in Antarctica was finding a place, any place, that had changed dramatically.</p>
<figure class="align-center ">
<img alt="Deep cracks leaves jagged columns of ice with a layer of snow at the top ready to tip into the sea." src="https://images.theconversation.com/files/451477/original/file-20220310-27-1xzxdke.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451477/original/file-20220310-27-1xzxdke.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451477/original/file-20220310-27-1xzxdke.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451477/original/file-20220310-27-1xzxdke.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451477/original/file-20220310-27-1xzxdke.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451477/original/file-20220310-27-1xzxdke.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451477/original/file-20220310-27-1xzxdke.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 breaks off the front of a glacier in Antarctica.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/xDhpn9zx2Fo">66 North via Unsplash</a></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/451495/original/file-20220311-25-zibl59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of the ice sheet showing faster flowing ice at the ice shelves and particularly around the edges of West Antarctica." src="https://images.theconversation.com/files/451495/original/file-20220311-25-zibl59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451495/original/file-20220311-25-zibl59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=605&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451495/original/file-20220311-25-zibl59.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=605&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451495/original/file-20220311-25-zibl59.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=605&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451495/original/file-20220311-25-zibl59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=761&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451495/original/file-20220311-25-zibl59.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=761&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451495/original/file-20220311-25-zibl59.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=761&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 map of Antarctica seen from above, most of it the ice sheet, shows the velocity of the ice flow ice. Thwaites Glacier is on the left.</span>
<span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/3849">NASA's Goddard Space Flight Center Scientific Visualization Studio</a></span>
</figcaption>
</figure>
<p>But now, as the surrounding air and ocean warm, areas of the Antarctic ice sheet that had been stable for thousands of years <a href="https://cires.colorado.edu/news/threat-thwaites-retreat-antarctica%E2%80%99s-riskiest-glacier">are breaking, thinning, melting</a>, or in some cases <a href="https://doi.org/10.3189/172756404781814005">collapsing in a heap</a>. As these edges of the ice react, they send a powerful reminder: If even a small part of the ice sheet were to completely crumble into the sea, the impact for the world’s coasts would be severe.</p>
<p>Like many geoscientists, I think about how the Earth looks below the part that we can see. For Antarctica, that means thinking about the landscape below the ice. What does the buried continent look like – and how does that rocky basement shape the future of the ice in a warming world?</p>
<h2>Visualizing the world below the ice</h2>
<p>Recent efforts to <a href="https://doi.org/10.5194/tc-7-375-2013">combine data from hundreds of airplane and ground-based studies</a> have given us a kind of <a href="https://doi.org/10.1038/s41561-019-0510-8">map of the continent below the ice.</a> It reveals two very different landscapes, divided by the Transantarctic Mountains.</p>
<p>In East Antarctica, the part closer to Australia, the continent is rugged and furrowed, with <a href="https://www.nsf.gov/news/news_summ.jsp?org=NSF&cntn_id=122290&preview=false">several small mountain ranges</a>. Some of these have alpine valleys, cut by the very first glaciers that formed on Antarctica 30 million years ago, when its climate resembled Alberta’s or Patagonia’s. Most of East Antarctica’s bedrock sits above sea level. This is where the city-size Conger ice shelf collapsed <a href="https://www.copernicus.eu/en/media/image-day-gallery/collapse-conger-ice-shelf">amid an unusually intense heat wave</a> in March 2022.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/451763/original/file-20220313-17-17obzrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A view of Antarctica's bedrock beneath the ice today shows islands in the west side and more above-sea bedrock in the east." src="https://images.theconversation.com/files/451763/original/file-20220313-17-17obzrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451763/original/file-20220313-17-17obzrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451763/original/file-20220313-17-17obzrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451763/original/file-20220313-17-17obzrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451763/original/file-20220313-17-17obzrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=508&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451763/original/file-20220313-17-17obzrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=508&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451763/original/file-20220313-17-17obzrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=508&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Below the ice, recent studies have mapped Antarctica’s bedrock and show much of the west side is below sea level.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.5194/tc-7-375-2013">Bedmap2; Fretwell 2013</a></span>
</figcaption>
</figure>
<p>In West Antarctica the bedrock is far different, with parts that are far deeper. This area was once the ocean bottom, a region where the continent was stretched and broken into smaller blocks with deep seabed between. Large islands made of volcanic mountain ranges are linked together by the thick blanket of ice. But the ice here is warmer, and moving faster. </p>
<p><a href="https://doi.org/10.1002/2015GL063861">As recently as 120,000 years ago</a>, this area was probably an open ocean – and definitely so in the <a href="https://doi.org/10.1016/B978-0-12-819109-5.00014-1">past 2 million years</a>. This is important because our climate today is <a href="https://www.climate.gov/news-features/climate-qa/whats-hottest-earths-ever-been">fast approaching temperatures</a> like those of a few million years ago.</p>
<p>The realization that the West Antarctic ice sheet was gone in the past is the cause of great concern in the global warming era.</p>
<h2>Early stages of a large-scale retreat</h2>
<p>Toward the coast of West Antarctica is a large area of ice called <a href="https://thwaitesglacier.org/about/facts">Thwaites Glacier</a>. This is the widest glacier on earth, at 70 miles across, draining an area nearly as large as Idaho.</p>
<p>Satellite <a href="https://doi.org/10.1038/s41586-018-0179-y">data tell us</a> that it is in the <a href="https://doi.org/10.1016/j.gloplacha.2017.04.008">early stages of a large-scale retreat</a>. The height of the surface has been dropping by up to 3 feet each year. Huge cracks have formed at the coast, and many large icebergs have been set adrift. The glacier is flowing at over a mile per year, and this speed has nearly doubled in the past three decades.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/AmSovbt5Bho?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Two decades of satellite data show the fastest ice loss in the vicinity of the Thwaites Glacier. NASA.</span></figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/451765/original/file-20220313-18-462rul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A view across the ice from an airplane showing many fractures." src="https://images.theconversation.com/files/451765/original/file-20220313-18-462rul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451765/original/file-20220313-18-462rul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451765/original/file-20220313-18-462rul.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451765/original/file-20220313-18-462rul.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451765/original/file-20220313-18-462rul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=584&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451765/original/file-20220313-18-462rul.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=584&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451765/original/file-20220313-18-462rul.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=584&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">From above, fractures are evident in the Thwaites Glacier.</span>
<span class="attribution"><span class="source">Ted Scambos</span></span>
</figcaption>
</figure>
<p>This area was noted early on as a place where the ice <a href="https://doi.org/10.1126/science.1249055">could lose its grip on the bedrock</a>. The region was termed the “<a href="https://doi.org/10.3189/S002214300001159X">weak underbelly” of the ice sheet</a>.</p>
<p>Some of the <a href="https://doi.org/10.1073/pnas.1821646116">first measurements</a> of the ice depth, using radio echo-sounding, showed that the center of West Antarctica had bedrock up to a mile and a half below sea level. The coastal area was shallower, with a few mountains and some higher ground; but a wide gap between the mountains lay near the coast. This is where Thwaites Glacier meets the sea.</p>
<p>This pattern, with deeper ice piled high near the center of an ice sheet, and shallower but still low bedrock near the coast, is a recipe for disaster – albeit a very slow-moving disaster.</p>
<p>Ice flows under its own weight – something we learned in high school earth science, but give it a thought now. With very tall and very deep ice near Antarctica’s center, a tremendous potential for faster flow exists. By being shallower near the edges, the flow is held back – grinding on the bedrock as it tries to leave, and having a shorter column of ice at the coast squeezing it outward.</p>
<figure class="align-center ">
<img alt="An Antarctic glacier flows between mountains. Lines in ice show that it's flowing." src="https://images.theconversation.com/files/451489/original/file-20220311-13-xkhec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451489/original/file-20220311-13-xkhec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451489/original/file-20220311-13-xkhec.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451489/original/file-20220311-13-xkhec.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451489/original/file-20220311-13-xkhec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451489/original/file-20220311-13-xkhec.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451489/original/file-20220311-13-xkhec.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An Antarctic glacier flows toward the sea.</span>
<span class="attribution"><span class="source">Erin Pettit</span></span>
</figcaption>
</figure>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/MR6-sgRqW0k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How warmer water is undermining the glacier.</span></figcaption>
</figure>
<p>If the ice were to step back far enough, the retreating front would go from “thin” ice – <a href="https://thwaitesglacier.org/about/facts">still nearly 3,000 feet thick</a> – to thicker ice toward the center of the continent. At the retreating edge, the ice would flow faster, because the ice is thicker now. By flowing faster, the glacier pulls down the ice behind it, allowing it to float, causing more retreat. This is what’s known as <a href="https://en.wikipedia.org/wiki/Marine_ice_sheet_instability">a positive feedback loop</a> – retreat leading to thicker ice at the front of the glacier, making for faster flow, leading to more retreat.</p>
<h2>Warming water: The assault from below</h2>
<p>But how would this retreat begin? Until recently, Thwaites had not changed a lot since it was <a href="https://thwaitesglacier.org/sites/default/files/2020-09/ThwaitesGlacierFactsSheetJune2020_1.pdf">first mapped</a> in the 1940s. Early on, scientists thought a retreat would be a result of warmer air and surface melting. But the cause of the changes at Thwaites seen in satellite data is not so easy to spot from the surface.</p>
<p><a href="https://antarcticsun.usap.gov/science/4457/">Beneath the ice</a>, however, at the point where the ice sheet first lifts off the continent and begins to jut out over the ocean as a floating ice shelf, the cause of the retreat becomes evident. Here, ocean water well above the melting point is <a href="https://doi.org/10.5194/tc-16-397-2022">eroding the base of the ice</a>, erasing it as an ice cube would disappear bobbing in a glass of water.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/451479/original/file-20220311-13-145nx3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of an ice shelf and glacier with water flowing under the ice shelf and eroding it at the seabed" src="https://images.theconversation.com/files/451479/original/file-20220311-13-145nx3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451479/original/file-20220311-13-145nx3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=264&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451479/original/file-20220311-13-145nx3v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=264&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451479/original/file-20220311-13-145nx3v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=264&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451479/original/file-20220311-13-145nx3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=332&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451479/original/file-20220311-13-145nx3v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=332&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451479/original/file-20220311-13-145nx3v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=332&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Warming water is reaching under the ice shelf and eroding it from below.</span>
<span class="attribution"><a class="source" href="https://www.sciencedirect.com/science/article/pii/S092181811630491X?via%3Dihub">Scambos et al 2017</a></span>
</figcaption>
</figure>
<p>Water that is capable of melting as much as 50 to 100 feet of ice every year meets the edge of the ice sheet here. This erosion lets the ice flow faster, pushing against the floating ice shelf.</p>
<p>The ice shelf is one of the restraining forces holding the ice sheet back. But pressure from the land ice is <a href="https://doi.org/10.1038/d41586-021-03758-y">slowly breaking this ice plate</a>. Like a board splintering under too much weight, it is developing huge cracks. When it gives way – and mapping of the fractures and speed of flow <a href="https://www.youtube.com/watch?v=uBbgWsR4-aw">suggests this is just a few years away</a> – it will be another step that allows the ice to flow faster, feeding the feedback loop.</p>
<h2>Up to 10 feet of sea level rise</h2>
<p>Looking back at the ice-covered continent from our camp this year, it is a sobering view. A huge glacier, flowing toward the coast, and stretching from horizon to horizon, rises up to the middle of the West Antarctic Ice Sheet. There is a palpable feeling that the ice is bearing down on the coast.</p>
<p>Ice is still ice – it doesn’t move that fast no matter what is driving it; but this giant area called West Antarctica could soon begin a multicentury decline that would add <a href="https://cires.colorado.edu/news/threat-thwaites-retreat-antarctica%E2%80%99s-riskiest-glacier">up to 10 feet</a> to sea level. In the process, the rate of sea level rise would increase severalfold, posing large challenges for people with a stake in coastal cities. Which is pretty much all of us.</p><img src="https://counter.theconversation.com/content/178828/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ted Scambos receives funding from the National Science Foundation and NASA.</span></em></p>Thwaites Glacier’s ice shelf appears to be splintering, and scientists fear it could give way in the next few years. A polar scientist takes us on a tour under the ice to explain the forces at work.Ted Scambos, Senior Research Scientist, CIRES, University of Colorado BoulderLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1782952022-03-29T12:36:30Z2022-03-29T12:36:30ZHow fast can we stop Earth from warming?<figure><img src="https://images.theconversation.com/files/453654/original/file-20220322-21-4h6qc0.jpg?ixlib=rb-1.1.0&rect=17%2C180%2C3864%2C2403&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The ocean retains heat for much longer than land does. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/crowded-sunset-silhouette-royalty-free-image/1179557108">Aliraza Khatri's Photography via Getty Images</a></span></figcaption></figure><p>Global warming doesn’t stop on a dime. If people everywhere stopped burning fossil fuels tomorrow, stored heat would still continue to warm the atmosphere.</p>
<p>Picture how a radiator heats a home. Water is heated by a boiler, and the hot water circulates through pipes and radiators in the house. The radiators warm up and heat the air in the room. Even after the boiler is turned off, the already heated water is still circulating through the system, heating the house. The radiators are, in fact, cooling down, but their stored heat is still warming the air in the room.</p>
<p>This is known as <a href="https://doi.org/10.1038/s41558-020-00955-x">committed warming</a>. Earth similarly has ways of storing and releasing heat. </p>
<p>Emerging research is refining scientists’ understanding of how Earth’s committed warming will affect the climate. Where we once thought it would take 40 years or longer for global surface air temperature to peak once humans stopped heating up the planet, research now suggests <a href="https://doi.org/10.1088/1748-9326/9/12/124002">temperature could peak in closer to 10 years</a>.</p>
<p>But that doesn’t mean the planet returns to its preindustrial climate or that we avoid disruptive effects such as sea level rise.</p>
<p>I am a professor of climate science, and my research and teaching focus on the usability of climate knowledge by practitioners such as urban planners, public health professionals and policymakers. Let’s take a look at the bigger picture.</p>
<h2>How understanding of peak warming has changed</h2>
<p>Historically, the <a href="https://www.carbonbrief.org/timeline-history-climate-modelling">first climate models</a> represented only the atmosphere and were greatly simplified. Over the years, scientists <a href="https://celebrating200years.noaa.gov/breakthroughs/climate_model/welcome.html">added oceans</a>, land, ice sheets, chemistry and biology.</p>
<p>Today’s models can more explicitly represent the behavior of greenhouse gases, especially carbon dioxide. That allows scientists to better separate heating due to carbon dioxide in the atmosphere from the role of heat stored in the ocean.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_WUNMzC98jI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Why global warming is ocean warming.</span></figcaption>
</figure>
<p>Thinking about our radiator analogy, increasing concentrations of greenhouse gases in Earth’s atmosphere keep the boiler on – holding energy near the surface and raising the temperature. Heat accumulates and is stored, <a href="https://climate.nasa.gov/vital-signs/ocean-heat/">mostly in the oceans</a>, which take on the role of the radiators. The heat is distributed around the world through weather and oceanic currents.</p>
<p>The <a href="https://bg.copernicus.org/articles/17/2987/2020/">current understanding</a> is that if all of the additional heating to the planet caused by humans was eliminated, a plausible outcome is that Earth would reach <a href="https://www.carbonbrief.org/explainer-will-global-warming-stop-as-soon-as-net-zero-emissions-are-reached">a global surface air temperature peak in closer to 10 years than 40</a>. The previous estimate of 40 or more years has been widely used over the years, <a href="https://theconversation.com/what-would-happen-to-the-climate-if-we-stopped-emitting-greenhouse-gases-today-35011">including by me</a>.</p>
<p>It is important to note that this is only the peak, when the temperature starts to stabilize – not the onset of rapid cooling or a reversal of climate change.</p>
<p>I believe there is <a href="https://bg.copernicus.org/articles/17/2987/2020/">enough uncertainty to justify caution</a> about exaggerating the significance of the new research’s results. The authors applied the concept of peak warming to global surface air temperature. Global surface air temperature is, metaphorically, the temperature in the “room,” and is not the best measure of climate change. The concept of instantly cutting off human-caused heating is also idealized and entirely unrealistic – doing that would involve much more than just ending fossil fuel use, including widespread changes to agriculture – and it only helps illustrate how parts of the climate might behave. </p>
<p>Even if the air temperature were to peak and stabilize, “<a href="https://youtu.be/AT5jdqHUeKM">committed ice melting</a>,” “committed sea level rise” and numerous other land and biological trends would continue to evolve from the accumulated heat. Some of these could, in fact, cause a <a href="https://doi.org/10.1130/G48580.1">release of carbon dioxide and methane</a>, especially from the Arctic and other high-latitude reservoirs that are <a href="https://yaleclimateconnections.org/2018/02/the-permafrost-bomb-is-ticking/">currently frozen</a>. </p>
<p>For these reasons and others, it is important to consider the how far into the future studies like this one look.</p>
<h2>Oceans in the future</h2>
<p>Oceans will continue to store heat and exchange it with the atmosphere. Even if emissions stopped, the excess heat that has been accumulating in the ocean since preindustrial times would influence the climate for another 100 years or more.</p>
<p>Because the ocean is dynamic, it has currents, and it will not simply diffuse its excess heat back into the atmosphere. There will be ups and downs as the temperature adjusts.</p>
<p>The oceans also influence the amount of carbon dioxide in the atmosphere, because carbon dioxide is both absorbed and emitted by the oceans. <a href="https://www.ncei.noaa.gov/products/paleoclimatology/paleo-perspectives/global-warming">Paleoclimate studies show</a> large changes in carbon dioxide and temperature in the past, with the oceans playing an important role.</p>
<figure class="align-center ">
<img alt="Chart showing ocean heating increasing fastest and going to greater depths over time." src="https://images.theconversation.com/files/453639/original/file-20220322-24-c0zec5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453639/original/file-20220322-24-c0zec5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=432&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453639/original/file-20220322-24-c0zec5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=432&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453639/original/file-20220322-24-c0zec5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=432&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453639/original/file-20220322-24-c0zec5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=543&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453639/original/file-20220322-24-c0zec5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=543&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453639/original/file-20220322-24-c0zec5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=543&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The chart shows how excess heat – thermal energy – has built up in ocean, land, ice and atmosphere since 1960 and moved to greater ocean depths with time. TOA CERES refers to the top of the atmosphere.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Earth%27s_Heat_Accumulation.png">Karina von Schuckman, LiJing Cheng, Matthew D. Palmer, James Hansen, Caterina Tassone, et al.</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Countries aren’t close to ending fossil fuel use</h2>
<p>The possibility that a policy intervention might have measurable impacts in <a href="https://doi.org/10.1088/1748-9326/9/12/124002">10 years</a> rather than several decades could motivate more aggressive efforts to remove carbon dioxide from the atmosphere. It would be very satisfying to see policy interventions having present rather than notional future benefits.</p>
<p>[<em>Over 150,000 readers rely on The Conversation’s newsletters to understand the world.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-150ksignup">Sign up today</a>.]</p>
<p>However, today, countries aren’t anywhere close to ending their fossil fuel use. Instead, all of the <a href="https://www.ipcc.ch/report/sixth-assessment-report-working-group-i/">evidence points to humanity experiencing rapid global warming</a> in the coming decades. </p>
<p>Our most robust finding is that the less carbon dioxide humans release, the better off humanity will be. Committed warming and human behavior point to a need to accelerate efforts both to reduce greenhouse gas emissions and to adapt to this warming planet now, rather than simply talking about how much needs to happen in the future.</p><img src="https://counter.theconversation.com/content/178295/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Rood receives funding from the National Oceanographic and Atmospheric Administration and the National Science Foundation. He is a co-principal investigator at the Great Lakes Integrated Sciences and Assessment Center at the University of Michigan.</span></em></p>If fossil fuel burning stopped, emerging research suggests air temperatures could level off sooner than expected. But that doesn’t mean the damage stops.Richard B. (Ricky) Rood, Professor of Climate and Space Sciences and Engineering, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1789862022-03-10T04:33:24Z2022-03-10T04:33:24ZWhether people prepare for natural disasters depends on how the message is sent<p>Coastal areas are at the frontline of natural hazards – a fact now thrown into sharp relief as flooding devastates parts of southeastern Australia. </p>
<p>Providing information is one of the most important ways governments can help communities cope with these events. Such information aims to encourage people to make more informed decisions about the risks they face and act accordingly.</p>
<p>But as our <a href="https://www.mdpi.com/2071-1050/14/5/2904/html">new research</a> shows, simply providing information is not enough. We found when authorities deliver generic information about natural hazards via passive means, such as radio ads and brochures, most households did not change their behaviour.</p>
<p>To ensure our communities remain resilient in the face of worsening natural disasters, governments must find better ways to deliver important messages.</p>
<figure class="align-center ">
<img alt="Ad reading 'be flood ready' with hand holding brochure" src="https://images.theconversation.com/files/451215/original/file-20220310-793-27gjo8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451215/original/file-20220310-793-27gjo8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=212&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451215/original/file-20220310-793-27gjo8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=212&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451215/original/file-20220310-793-27gjo8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=212&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451215/original/file-20220310-793-27gjo8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=266&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451215/original/file-20220310-793-27gjo8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=266&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451215/original/file-20220310-793-27gjo8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=266&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An ACT government ad promoting flood readiness. Sometimes, providing passive information is not enough.</span>
<span class="attribution"><span class="source">ACT government</span></span>
</figcaption>
</figure>
<h2>Barriers to being prepared</h2>
<p>Numerous studies have suggested providing the public with information can overcome knowledge gaps, overcome inertia and prompt people to change their behaviour.</p>
<p>But even if a person is informed about the risks of natural hazards, other factors can influence their willingness to prepare for them.</p>
<p>For example, financial constraints might mean a person cannot stock up on food supplies before a storm hits. </p>
<p>Some people may simply not consider themselves to be at risk. Others may have competing priorities such as work or child care.</p>
<p>That means we need to better understand what types of information best lead to behaviour change and how barriers to action can be overcome.</p>
<h2>Does passive information work?</h2>
<p>Information can be categorised into three types: </p>
<ul>
<li><p>passive (seeks to reach a wide audience through, for example, online communication, pamphlets or radio ads)</p></li>
<li><p>interactive (information derived through interactions with other people)</p></li>
<li><p>experiential (information gleaned from personal life experiences).</p></li>
</ul>
<p>Information provided by governments to coastal households is predominantly passive.
For example, households are often encouraged to access information on natural hazards such as <a href="https://www.ses.nsw.gov.au/flood-resources/before-a-flood/know-your-risk/">floods</a>, and how to <a href="https://www.climatechange.environment.nsw.gov.au/how-households-can-adapt">prepare</a> for climate change. </p>
<p>We set out to test the effectiveness of this passive approach to delivering information.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/weather-forecasts-wont-save-us-we-must-pre-empt-monster-floods-years-before-they-hit-178767">Weather forecasts won't save us – we must pre-empt monster floods years before they hit</a>
</strong>
</em>
</p>
<hr>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/aV_wyCdjpqk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>What we found</h2>
<p>Our study focused on two Australian coastal communities: Mandurah in Western Australia and Moreton Bay in Queensland. </p>
<p>We surveyed households and conducted interviews with locals. We explored the types of information that shape responses to three hazard scenarios: a heatwave, a severe storm and sea-level rise. </p>
<p>People who wanted more information about their exposure to future climate risks were more likely to:</p>
<ul>
<li>perceive their local area as vulnerable to environmental hazards</li>
<li>consider local environmental health important to their households’ wellbeing. </li>
</ul>
<p>Likewise, people who wanted information on preparing for climate hazards believed:</p>
<ul>
<li>households were very capable of managing the impacts</li>
<li>their local council was capable of preventing harm.</li>
</ul>
<figure class="align-center ">
<img alt="pool collapsed onto beach after storm" src="https://images.theconversation.com/files/450587/original/file-20220308-85823-1xwtzfa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/450587/original/file-20220308-85823-1xwtzfa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450587/original/file-20220308-85823-1xwtzfa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450587/original/file-20220308-85823-1xwtzfa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450587/original/file-20220308-85823-1xwtzfa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=489&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450587/original/file-20220308-85823-1xwtzfa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=489&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450587/original/file-20220308-85823-1xwtzfa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=489&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Coastal communities are particularly vulnerable to storms and other extreme weather.</span>
<span class="attribution"><span class="source">David Moir/AAP</span></span>
</figcaption>
</figure>
<p>However, passive information rarely informed a person’s response to natural hazards. Instead, people tended to believe in the power of “common sense”, especially when dealing with short-term impacts of hazards.</p>
<p>For example, one interviewee said no response to a heatwave was required, but “if you do have to go out you don’t go out for very long”.</p>
<p>Household action was also informed by past experience. One Mandurah resident told us:</p>
<blockquote>
<p>We did have a scenario here […] we had a pretty severe storm and were out of power. So I have lots of candles and you just get by.</p>
</blockquote>
<p>Conversely, a Moreton Bay resident drew on their past exposure to a storm to justify the limited need for action:</p>
<blockquote>
<p>The area has never been affected by those sort of floods […] it hasn’t stopped us from doing the day-to-day things like getting kids to school.</p>
</blockquote>
<p>But as extreme weather worsens under climate change, basing decisions on past experiences may not be sufficient.</p>
<p>When it came to responding to hazards, most people adopted short-term coping strategies, such as securing loose items in their yard. </p>
<p>Other more proactive actions, such as installing window protection, were limited. There was also a lack of collective actions such as joining local recovery or conservation efforts.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-floods-have-killed-at-least-21-australians-adapting-to-a-harsher-climate-is-now-a-life-or-death-matter-178761">The floods have killed at least 21 Australians. Adapting to a harsher climate is now a life-or-death matter</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="crowded beach on hot day" src="https://images.theconversation.com/files/451218/original/file-20220310-23-166zzmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451218/original/file-20220310-23-166zzmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451218/original/file-20220310-23-166zzmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451218/original/file-20220310-23-166zzmo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451218/original/file-20220310-23-166zzmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451218/original/file-20220310-23-166zzmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451218/original/file-20220310-23-166zzmo.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">Respondents favoured a common sense approach to natural hazards, such as not staying outside for long periods during heatwaves.</span>
<span class="attribution"><span class="source">Dan Himbrechts/AAP</span></span>
</figcaption>
</figure>
<h2>Where to from here?</h2>
<p>Prior exposure to a climate hazard appears to drive some people to adapt. But most households generally employ coping strategies, informed by perceptions of common sense. </p>
<p>So what type of information best promotes the transition from short-term coping with natural hazards to longer-term adaptation?</p>
<p>The answer may lie in promoting adaptation well before natural disasters hit as a “common sense” response to the climate threat.</p>
<p>Passive information rarely contains targeted information that can capture the interest of all households. So there’s value in moving beyond this approach.</p>
<p>Two-way communication tools such as workshops, demonstrations, community events and harnessing opinion leaders offer promise. They enable collective discussion where participants can share experiences, beliefs and values, building trust and collaboration. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/under-resourced-and-undermined-as-floods-hit-south-west-sydney-our-research-shows-councils-arent-prepared-178293">Under-resourced and undermined: as floods hit south-west Sydney, our research shows councils aren't prepared</a>
</strong>
</em>
</p>
<hr>
<p>Some households value passive information. But if resilience to climate hazards is indeed the objective, communication promoting household response must change.</p>
<p>Whether information resonates with a household depends on various factors, including their capacity to respond. So improving people’s confidence in their capability to act may also trigger better adaptation.</p>
<p>But households should not be seen solely as individual units acting to reduce their personal risk. They are also part of a broader system and can contribute to social change through collective action.</p>
<p>This might include collectively lobbying politicians, sharing experiences and strategies, and helping each other during times of crisis.</p>
<p>As climate change threatens to bring more severe and frequent natural disasters, more research is needed into information that encourages people to cope and adapt – both individually and together.</p><img src="https://counter.theconversation.com/content/178986/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Carmen Elrick-Barr acknowledges support from Australian Government through the Australian Research Council’s Discovery Projects Funding Scheme (Projects FT180100652 and DP1093583). </span></em></p><p class="fine-print"><em><span>Tim Smith acknowledges support from the Australian Research Council's Discovery Projects Funding Scheme (Projects FT180100652 and DP1093583). The views expressed herein are those of the authors, and are not necessarily those of the University of the Sunshine Coast, the Australian Research Council, or the Australian Government.
</span></em></p>Simply providing passive information is not enough. Governments must find better ways to deliver important messages about natural hazards.Carmen Elrick-Barr, Research Fellow, University of the Sunshine CoastTim Smith, Professor and ARC Future Fellow, University of the Sunshine CoastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1664172021-09-13T20:04:26Z2021-09-13T20:04:26ZHow much will our oceans warm and cause sea levels to rise this century? We’ve just improved our estimate<figure><img src="https://images.theconversation.com/files/420680/original/file-20210913-25-1so9vql.jpeg?ixlib=rb-1.1.0&rect=1%2C0%2C997%2C667&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Jakob Weis, University of Tasmania</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Knowing how much sea levels are likely to rise during this century is vital to our understanding of future climate change, but previous estimates have generated wide ranges of uncertainty. In our research, <a href="https://www.nature.com/articles/s41558-021-01151-1">published today in Nature Climate Change</a>, we provide an improved estimate of how much our oceans are going to warm and its contribution to sea level rise, with the help of 15 years’ worth of measurements collected by a global array of autonomous underwater sampling floats.</p>
<p>Our analysis shows that without dramatic reductions in greenhouse gas emissions, by the end of this century the upper 2,000 metres of the ocean is likely to warm by 11-15 times the amount of warming observed during 2005-19. Water expands as it gets warmer, so this warming will cause sea levels to rise by 17-26 centimetres. This is about one-third of the total projected rise, alongside contributions from deep ocean warming, and melting of glaciers and polar ice sheets.</p>
<p>Ocean warming is a direct consequence of rising greenhouse gas concentrations in the atmosphere as a result of our burning of fossil fuels. This results in an imbalance between the energy arriving from the Sun, and the energy radiated out into space. About <a href="https://essd.copernicus.org/articles/12/2013/2020/">90%</a> of the excess heat energy in the climate system over the past 50 years is stored in the ocean, and only about 1% in the warming atmosphere.</p>
<p>Warming oceans cause sea levels to rise, both directly via heat expansion, and indirectly through melting of ice shelves. Warming oceans also affect marine ecosystems, for example through coral bleaching, and play a role in weather events such as the formation of tropical cyclones. </p>
<p>Systematic observations of ocean temperatures began in the 19th century, but it was only in the second half of the 20th century that enough observations were made to measure ocean heat content consistently around the globe. </p>
<p>Since the 1970s these observations indicate <a href="https://essd.copernicus.org/articles/12/2013/2020/">an increase in ocean heat content</a>. But these measurements have significant uncertainties because the observations have been relatively sparse, particularly in the southern hemisphere and at depths below 700m. </p>
<p>To improve this situation, the <a href="https://argo.ucsd.edu/">Argo project</a> has deployed a fleet of autonomous profiling floats to collect data from around the world. Since the early 2000s, they have measured temperatures in the upper 2,000m of the oceans, and sent the data via satellite to analysis centres around the world. </p>
<p>These data are of uniform high quality and cover the vast majority of the open oceans. As a result, we have been able to calculate a much better estimate of the amount of heat accumulating in the world’s oceans. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/420421/original/file-20210910-137-1dd62qe.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/420421/original/file-20210910-137-1dd62qe.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/420421/original/file-20210910-137-1dd62qe.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=274&fit=crop&dpr=1 600w, https://images.theconversation.com/files/420421/original/file-20210910-137-1dd62qe.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=274&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/420421/original/file-20210910-137-1dd62qe.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=274&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/420421/original/file-20210910-137-1dd62qe.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=345&fit=crop&dpr=1 754w, https://images.theconversation.com/files/420421/original/file-20210910-137-1dd62qe.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=345&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/420421/original/file-20210910-137-1dd62qe.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=345&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 distribution of Argo floats.</span>
<span class="attribution"><span class="source">Argo project</span></span>
</figcaption>
</figure>
<p>The global ocean heat content continued to increase unabated during the <a href="https://theconversation.com/ocean-depths-heating-steadily-despite-global-warming-pause-37047">temporary slowdown in global surface warming</a> in the beginning of this century. This is because ocean warming is less affected than surface warming by natural yearly fluctuations in climate. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ocean-depths-heating-steadily-despite-global-warming-pause-37047">Ocean depths heating steadily despite global warming 'pause'</a>
</strong>
</em>
</p>
<hr>
<h2>Current observations, future warming</h2>
<p>To estimate future ocean warming, we need to take the Argo observations as a basis and then use climate models to project them into the future. But to do that, we need to know which models are in closest agreement with new, more accurate direct measurements of ocean heat provided by the Argo data.</p>
<p>The <a href="https://www.wcrp-climate.org/images/modelling/WGCM/CMIP/CMIP6FinalDesign_GMD_180329.pdf">latest climate models</a>, used in last month’s landmark report by the Intergovernmental Panel on Climate Change, all show ocean warming over the period of available Argo observations, and they project that warming will continue in the future, albeit with a wide range of uncertainties.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/420674/original/file-20210913-21-a0vlo6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/420674/original/file-20210913-21-a0vlo6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/420674/original/file-20210913-21-a0vlo6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=580&fit=crop&dpr=1 600w, https://images.theconversation.com/files/420674/original/file-20210913-21-a0vlo6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=580&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/420674/original/file-20210913-21-a0vlo6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=580&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/420674/original/file-20210913-21-a0vlo6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=728&fit=crop&dpr=1 754w, https://images.theconversation.com/files/420674/original/file-20210913-21-a0vlo6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=728&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/420674/original/file-20210913-21-a0vlo6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=728&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ocean warming magnitudes from latest climate model simulations and Argo observations.</span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-climate-sensitivity-18815">Explainer: what is climate sensitivity?</a>
</strong>
</em>
</p>
<hr>
<p>By comparing the Argo temperature data for 2005-19 with the simulations generated by models for that period, we used a statistical approach called “<a href="https://www.nature.com/articles/s41558-019-0436-6">emergent constraint</a>” to reduce uncertainties in model future projections, based on information about the ocean warming we know has already occurred. These constrained projections then provided an improved estimate of how much heat energy will accumulate in the oceans by the end of the century. </p>
<p>By 2081–2100, under a scenario in which global greenhouse emissions continue on their current high trajectory, we found the upper 2,000m of the ocean is likely to warm by 11-15 times the amount of warming observed during 2005-19. This corresponds to 17–26cm of sea level rise from ocean thermal expansion. </p>
<p>Climate models can also make predictions based on a range of different future greenhouse gas emissions. Strong emissions reductions, consistent with bringing surface global warming to within about 2°C of pre-industrial temperatures, would reduce the projected warming in the upper 2,000m of the ocean by about half — that is, between five and nine times the ocean warming already seen in 2005-19. </p>
<p>This would equate to 8-14cm of sea level rise due to thermal expansion. Of course, reducing emissions so as to hit the more ambitious Paris target of 1.5°C surface warming would reduce these impacts even further. </p>
<h2>Other factors linked to sea levels</h2>
<p>There are several other factors that will also drive up sea levels, besides the heat influx into the upper oceans investigated by our research. There is also warming of the deep ocean below 2,000m, which is still under-sampled in the current observing system, as well as the effects of melting from glaciers and polar ice sheets.</p>
<p>This indicates that even with strong policy action to reduce greenhouse gas emissions, the oceans will continue to warm and sea levels will continue to rise <a href="https://theconversation.com/if-we-stopped-emitting-greenhouse-gases-right-now-would-we-stop-climate-change-78882">well after surface warming is stabilised</a>, but at a much reduced rate, making it easier to adapt to the remaining changes. Cutting greenhouse gas emissions earlier rather than later will be more effective at slowing ocean warming and sea level rise. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/if-we-stopped-emitting-greenhouse-gases-right-now-would-we-stop-climate-change-78882">If we stopped emitting greenhouse gases right now, would we stop climate change?</a>
</strong>
</em>
</p>
<hr>
<p>Our improved projection is founded on a network of ocean observations that are far more extensive and reliable than anything available before. Sustaining the ocean observing system into the future, and extending it to the deep ocean and to areas not covered by the present Argo program, will allow us to make more reliable climate projections in the future.</p><img src="https://counter.theconversation.com/content/166417/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kewei Lyu receives funding from the Centre for Southern Hemisphere Oceans Research (CSHOR).</span></em></p><p class="fine-print"><em><span>John Church receives funding from The Australian Research Council and the Centre for Southern Hemisphere Oceans Research (CSHOR), jointly funded by the Qingdao National Laboratory for Marine Science and Technology (QNLM, China) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO, Australia).</span></em></p><p class="fine-print"><em><span>Xuebin Zhang received funding from Pacific Climate Change Science Program (PCCSP) and follow-up Pacific-Australia Climate Change Science and Adaptation Planning program (PACCSAP), both of which were funded by the Australian Government’s International Climate Change Adaptation Initiative, and also from Australian Climate Change Science Programme (ACCSP), National Environmental Science Programme (NESP), and Centre for Southern Hemisphere Ocean Research (CSHOR).</span></em></p>A new analysis, using 15 years of autonomous underwater measurements and simulations from the latest global climate models, refined our estimate of future ocean warming and sea level rise.Kewei Lyu, Postdoctoral Researcher in Ocean and Climate, CSIROJohn Church, Chair Professor, Climate Change Research Centre, UNSW SydneyXuebin Zhang, Principal Research Scientist, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1658722021-08-16T19:52:37Z2021-08-16T19:52:37ZForget massive seawalls, coastal wetlands offer the best storm protection money can buy<figure><img src="https://images.theconversation.com/files/416266/original/file-20210816-13-1mc83jx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">shutterstock</span> </figcaption></figure><p>Coastal communities around the world are facing increasing threats from tropical cyclones. Climate change is causing rising sea levels and bigger, more frequent storms. </p>
<p>Many coastal communities are pondering what to do. Should they build massive seawalls in a bid to protect existing infrastructure? Do they give up on their current coastal locations and retreat inland? Or is there another way?</p>
<p>In the US, the US Army Corps of Engineers has proposed building a 20-foot high <a href="https://www.nytimes.com/2021/06/02/us/miami-fl-seawall-hurricanes.html?searchResultPosition=4">giant seawall</a> to protect Miami, the third most populous metropolis on the US east coast. The US$6 billion proposal is tentative and at least five years off, but sure to be among many proposals in the coming years to protect coastal communities from storms.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-20-foot-sea-wall-wont-save-miami-how-living-structures-can-help-protect-the-coast-and-keep-the-paradise-vibe-165076">A 20-foot sea wall won’t save Miami – how living structures can help protect the coast and keep the paradise vibe</a>
</strong>
</em>
</p>
<hr>
<p>But seawalls are expensive to build, require constant maintenance and provide limited protection. </p>
<p>Consider China, which already has a huge number of seawalls built for storm protection. A <a href="http://www.robertcostanza.com/wp-content/uploads/2019/03/2019_J_Liu-et-al.-China-storm-protection-EcoServ.pdf">2019 study</a> analysed the impact of 127 storms on China between 1989 and 2016. </p>
<p>Coastal wetlands were far more cost effective in preventing storm damages. They also provided many other ecosystem services that seawalls do not.</p>
<h2>How wetlands reduce storm effects</h2>
<p>Coastal wetlands reduce the damaging effects of tropical cyclones on coastal communities by absorbing storm energy in ways that neither solid land nor open water can. </p>
<p>The <a href="http://www.robertcostanza.com/wp-content/uploads/2017/02/2008_J_Costanza_HurricaneProtection.pdf">mechanisms involved</a> include decreasing the area of open water (fetch) for wind to form waves, increasing drag on water motion and hence the amplitude of a storm surge, reducing direct wind effects on the water surface, and directly absorbing wave energy.</p>
<p>Wetland vegetation contributes by decreasing surges and waves and maintaining shallow water depths that have the same effect. Wetlands also reduce flood damages by absorbing flood waters caused by rain and moderating their effects on built-up areas.</p>
<figure class="align-center ">
<img alt="Coastal wetlands can absorb storm energy in ways neither solid land nor open water can." src="https://images.theconversation.com/files/416272/original/file-20210816-6624-12mrdl5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/416272/original/file-20210816-6624-12mrdl5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/416272/original/file-20210816-6624-12mrdl5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/416272/original/file-20210816-6624-12mrdl5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/416272/original/file-20210816-6624-12mrdl5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/416272/original/file-20210816-6624-12mrdl5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/416272/original/file-20210816-6624-12mrdl5.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">Coastal wetlands can absorb storm energy in ways neither solid land nor open water can.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>In 2008 I and colleagues estimated coastal wetlands in the US provided storm protection services worth US$23 billion a year.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0959378021001072">Our new study</a> estimates the global value of coastal wetlands to storm protection services is US$450 billion a year (calculated at 2015 value) with 4,600 lives saved annually. </p>
<p>To make this calculation, we used the records of more than 1,000 tropical cyclones since 1902 that caused property damage and/or human casualties in 71 countries. Our study took advantage of improved storm tracking, better global land-use mapping and damage-assessment databases, along with improved computational capabilities to model the relationships between coastal wetlands and avoided damages and deaths from tropical cyclones.</p>
<p>The 40 million hectares of coastal wetlands in storm-prone areas provided an average of US$11,000 per hectare a year in avoided storm damages.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/rising-seas-allow-coastal-wetlands-to-store-more-carbon-113020">Rising seas allow coastal wetlands to store more carbon</a>
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<h2>Pacific nations benefit most</h2>
<p>The degree to which coastal wetlands provide storm protection varies between countries (and within countries). Key factors are storm probability, amount of built infrastructure in storm-prone areas, if wetlands are in storm-prone areas, and coastal conditions. </p>
<p>The top five countries in terms of annual avoided damages (all in 2015 US dollar values) are the United States (US$200 billion), China (US$157 billion), the Philippines (US$47 billion), Japan (US$24 billion) and Mexico (US$15 billion). </p>
<p>In terms of lives saved annually, the top five are: China (1,309); the Philippines (976); the United States (469)l India (414); and Bangladesh (360).</p>
<figure class="align-center ">
<img alt="Floodwaters inundate Manila suburbs in November 2020 following Typhoon Vamco." src="https://images.theconversation.com/files/416276/original/file-20210816-6629-v6024o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/416276/original/file-20210816-6629-v6024o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/416276/original/file-20210816-6629-v6024o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/416276/original/file-20210816-6629-v6024o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/416276/original/file-20210816-6629-v6024o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/416276/original/file-20210816-6629-v6024o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/416276/original/file-20210816-6629-v6024o.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">
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<span class="caption">Floodwaters inundate Manila suburbs in November 2020 following Typhoon Vamco.</span>
<span class="attribution"><span class="source">Ace Morandante/Malacanang Presidential Photographers Division/AP</span></span>
</figcaption>
</figure>
<h2>Other ecosystem services</h2>
<p>Coastal wetlands also provide other valuable ecosystem services. They provide nursery habitat for many commercially important marine species, recreational opportunities, carbon sequestration, management of sediment and nutrient run-off, and many other valuable services. </p>
<p>In <a href="https://www.sciencedirect.com/science/article/abs/pii/S0959378014000685">2014</a> I and colleagues estimated the value of other ecosystem services provided by wetlands (over and above storm protection) at about $US 135,000 a hectare a year.</p>
<p>But land-use changes, including the loss of coastal wetlands, has been eroding both services. Since 1900 the world has <a href="https://www.publish.csiro.au/mf/mf14173">lost up to 70%</a> of its wetlands (Davidson, 2014). </p>
<p>Preserving and restoring coastal wetlands is a very cost-effective strategy for society, and can significantly <a href="http://www.idakub.com/academics/wp-content/uploads/2017/02/2017_J_Kubiszewski_ESscenarios.pdf">increase well-being</a> for humans and the rest of nature.</p>
<p>With the frequency and intensity of tropical cyclones and other extreme weather events projected to further increase, the value of coastal wetlands will increase in the future. This justifies investing much more in their conservation and restoration.</p><img src="https://counter.theconversation.com/content/165872/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Costanza 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>As weather becomes more extreme, the value of coastal wetlands is increasing.Robert Costanza, Professor and VC's Chair, Crawford School of Public Policy, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1658822021-08-12T03:31:37Z2021-08-12T03:31:37Z‘How high above sea level am I?’ If you’ve googled this, you’re likely asking the wrong question — an expert explains<figure><img src="https://images.theconversation.com/files/415608/original/file-20210811-25-sietvh.jpeg?ixlib=rb-1.1.0&rect=71%2C215%2C5892%2C3673&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The latest report from the United Nations Intergovernmental Panel on Climate Change is confronting. It finds global mean sea levels rose by about 20 centimetres between 1901 and 2018. In fact, sea levels have risen faster over the last hundred years than any time in the last 3,000 years.</p>
<p>This acceleration is expected to continue. A further 15-25cm of sea level rise is expected by 2050, with little sensitivity to greenhouse gas emissions between now and then. Beyond 2050, however, the amount of sea level rise will largely depend on our future emissions. </p>
<p>In a low-emissions scenario, we can expect sea levels to rise to about 38cm above the 1995–2014 average by the year 2100. In a high-emissions scenario this is expected to more than double to 77cm.</p>
<p>In either case, who will feel the effects of sea level rise? And how much does your location’s height above sea level really matter? It’s a question a lot of you have been googling since the report’s release. But the answer isn’t straightforward. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/this-is-the-most-sobering-report-card-yet-on-climate-change-and-earths-future-heres-what-you-need-to-know-165395">This is the most sobering report card yet on climate change and Earth's future. Here’s what you need to know</a>
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<h2>Sea level rise isn’t uniform</h2>
<p>Since satellites began measuring sea surface height almost three decades ago we have learned sea level rise is not uniform across the globe. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/m5PPURqEONI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The map on the left in this video shows daily sea level variations since 1993, while the curve on the right shows the month-by-month global mean sea level.</span></figcaption>
</figure>
<p>In fact, sea levels <a href="https://www.aviso.altimetry.fr/en/data/products/ocean-indicators-products/mean-sea-level.html">can vary</a> quite substantially on a year-to-year and decade-to-decade basis. However, we know much of this regional variability is driven by surface wind changes — and will typically decrease over long periods. </p>
<p>So while the IPCC report’s projections are for global mean sea level for the year 2100, most coastal locations will experience a sea level rise within 20% of the projections (which are subject to change beyond 2050 depending on global emissions).</p>
<h2>Flood zones and drainage</h2>
<p>Elevation above the high tide is an important factor in determining how at risk a particular location is of experiencing flooding due to sea level rise. </p>
<p>In low elevation coastal zones, physical distance to the coast and certain topographic features in the area such as sand dunes, wetlands and human built structures like levies and flood walls can act as a buffer to sea level rise. </p>
<p>That said, current and projected sea level rise may still pose a significant risk to regions with these buffers, as there are many ways by which sea level rise can lead to flooding. </p>
<p>For instance, as sea levels rise water from the sea can inundate storm water drainage systems and end up flooding inland regions with elevations below (or which will eventually be below) sea level. This is because drainage largely depends on gravity, and some storm water systems don’t have flood gates to stop water entering from the ocean.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/7tkBUkrxvrg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Here we see Bobbin Head in NSW flood during a king tide. This problem will become more pronounced as sea levels rise and will require clever engineering solutions, such as drainage pumps to push water back out to sea.</span></figcaption>
</figure>
<p>There are also cases where man-made features intended to help protect people from sea level impacts can be breached, resulting in flooding. One prominent example was the New Orleans flooding that occurred during Hurricane Katrina, when the man-made flood levee system <a href="http://www.hurricanescience.org/history/studies/katrinacase/impacts/.">suffered many failures</a></p>
<p>The tidal range around Australia <a href="https://media.bom.gov.au/social/blog/1677/explainer-tidal-rangethe-difference-between-high-and-low-tide-around-australia/">varies</a> from less than 1m in some parts such as southwest Australia, to more than 8m in other parts such as the northwest. </p>
<p>The tidal range in an area determines how quickly flooding impacts will increase as sea levels rise. If two regions have the same elevation, as the high tide rises past the regions’ elevation, the region with a smaller tidal range will likely struggle with more flooding and for longer than the region with a larger tidal range.</p>
<h2>Beach erosion increases risk</h2>
<p>Yet all of the above hasn’t considered the fact our beaches are naturally mobile systems which respond to change. This is why the relationship between an assets elevation above the high tide mark and risk of flooding is less straightforward at low elevation coastal zones — where 11% of Australia’s <a href="https://sedac.ciesin.columbia.edu/data/set/lecz-urban-rural-population-land-area-estimates-v2">population lives</a>.</p>
<p>When sea levels rise, the shape of the coastline changes with it and can move inland to a great extent. If sea levels rise by 1m, the coast can erode inland by 1km or more. This can <a href="https://www.nature.com/articles/s41558-020-00934-2">potentially</a> <a href="https://doi.org/10.1038/s41558-020-0697-0">create risk</a> for properties even if they are currently above the height of the projected sea level rise. </p>
<p>Australia has many retreating coastlines, often forming striking erosional landforms such as The Great Ocean Road region.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-world-may-lose-half-its-sandy-beaches-by-2100-its-not-too-late-to-save-most-of-them-132586">The world may lose half its sandy beaches by 2100. It’s not too late to save most of them</a>
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<hr>
<p>However, the response of the coastline can also be moderated by natural and human factors. In some regions, coastal elevation is actually increasing due to sediment being deposited, or tectonic uplift raising the coast as fast (or even faster) than rising sea levels. </p>
<p>In Australia, this is especially pronounced in estuaries with a riverine supply of sediments and where vegetation such as mangroves, saltmarshes and dune vegetation help <a href="https://www.nature.com/articles/s41586-018-0476-5">collect sediment</a> in their root systems.</p>
<p>We know sea level rise is with us for the long haul. And it’s now inevitable we will have to adapt to changes along our coasts. We’re already using a number of approaches to counteract projected sea level rise in Australia, including: </p>
<ul>
<li>sand renourishment of beaches</li>
<li>the formation of more seagrass, saltmarsh and mangrove habitats</li>
<li>construction of seawalls and other hard coastal protection measures.</li>
</ul>
<p>But it’s important to note we still have a choice for how much and how quickly sea levels will rise beyond 2050. So perhaps, instead of googling your current elevation, a more pragmatic approach would be to think of what you can do to help protect your own coasts and reduce your carbon footprint.</p><img src="https://counter.theconversation.com/content/165882/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shayne McGregor receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Nerilie Abram receives funding from the Australian Research Council. She is a member of the international Climate Crisis Advisory Group.</span></em></p><p class="fine-print"><em><span>Ruth Reef receives funding from the Australian Research Council to study how vegetated shorelines respond to rising sea levels in Australia. </span></em></p>The IPCC report has laid out some alarming sea level projections for the future. But the relationship between sea level rise and real-world risk is complex.Shayne McGregor, Associate professor, Monash UniversityNerilie Abram, Chief Investigator for the ARC Centre of Excellence for Climate Extremes; Deputy Director for the Australian Centre for Excellence in Antarctic Science, Australian National UniversityRuth Reef, Associate Professor, School of Earth Atmosphere and Environment, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1653882021-08-09T19:59:20Z2021-08-09T19:59:20ZTorres Strait Islanders face more than their fair share of health impacts from climate change<p>Torres Strait Islander peoples intend to live on their traditional country long-term. Living on the northernmost islands of Queensland allows these “saltwater people” to maintain their cultural responsibilities, identity and kinship connections. </p>
<p>Caring for country and keeping these connections can also <a href="https://pubmed.ncbi.nlm.nih.gov/21933367/">bring health benefits</a>. However, climate change increases the risks of negative health impacts. </p>
<p>There is escalating <a href="https://www.clientearth.org/torres-strait-islander-takes-a-stand-against-climate-injustice-on-world-stage/">outrage</a> about these and other climate impacts on health by Traditional Owners and <a href="https://www.theguardian.com/australia-news/2019/dec/08/torres-strait-doctors-issue-call-to-arms-over-climate-change-impact-on-indigenous-health">by medical personnel</a>. Both groups are calling for urgent climate action. </p>
<p>Our research team includes two <a href="https://www.tsra.gov.au/the-torres-strait/regional-map/communities/httpwww.tsra.gov.authe-torres-straitcommunity-profilesbadu.aspx">Badu Island</a> men who are public health researchers, an infectious diseases doctor, and two environmental health researchers. We reviewed the evidence about climate-sensitive infectious diseases in the region.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mondays-ipcc-report-is-a-really-big-deal-for-climate-change-so-what-is-it-and-why-should-we-trust-it-165614">Monday's IPCC report is a really big deal for climate change. So what is it? And why should we trust it?</a>
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<h2>“If our connection to these lands disappears, our Indigenous culture disappears”</h2>
<p>Mr Kabay Tamu is one of eight of <a href="https://www.theguardian.com/australia-news/2019/may/13/torres-strait-islanders-take-climate-change-complaint-to-the-united-nations">Torres Strait Islanders who sought action against the Australian government through the United Nations’ Human Rights Committee</a> in 2019. They assert Australia’s responses to reduce climate change-causing emissions or to develop adaptation measures are inadequate, and constitute human rights violations. </p>
<p><a href="https://www.clientearth.org/torres-strait-islander-takes-a-stand-against-climate-injustice-on-world-stage/">Mr Tamu said in his speech</a>:</p>
<blockquote>
<p>Our islands have been continuously inhabited by Indigenous people for tens of thousands of years, but the climate crisis is endangering all of this. Rising seas caused by man-made climate change are threatening homes, swamping burial grounds and washing away sacred cultural sites […] We, as a people, are connected to these islands through our cultural practices and traditions. If our connection to these lands disappears, our Indigenous culture disappears.</p>
</blockquote>
<p><a href="https://www.tandfonline.com/doi/abs/10.1080/09603123.2020.1777948">Research</a> provides <a href="https://www.tsra.gov.au/__data/assets/pdf_file/0008/23012/TSRA-Climate-Change-and-Health-First-Pass-Risk-Assessment.pdf">further evidence</a> of human-induced climate change impacts in the Torres Strait Islands. Cyclones are projected to become more intense. Drought conditions in this region have affected the security of water supply, requiring the installation of mobile desalination plants. Changes to temperature and rainfall have affected the range and extent of mosquito species that are vectors for dengue virus.</p>
<h2>“Ensure our population is as healthy as possible for climate change”</h2>
<p>An emergency call for increased attention to climate change and health impacts on <a href="https://www.theguardian.com/australia-news/2019/dec/08/torres-strait-doctors-issue-call-to-arms-over-climate-change-impact-on-indigenous-health">Torres Strait Islander peoples</a> was made in 2019 by 22 medical professionals working in the Queensland government’s Torres and Cape Health and Hospital Service region. They stated:</p>
<blockquote>
<p>[In the Torres Strait], climate change is a health emergency. We [medical officers] are concerned about the immediate effects of heat stress and extreme weather events as well as the long-term effects […] Vulnerable populations are disproportionately affected by climate change and unabated climate change will only steepen this social health gradient […] Proper investment […] is required to ensure our population is as healthy as possible for climate change</p>
</blockquote>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CRD0CepA-dW","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>20% of Queensland’s diagnoses in only 0.5% of the state’s population</h2>
<p>In our research, we sought to identify climate-sensitive infectious diseases that are currently or speculated to increase occurrence in the Torres Strait Islands. We compiled case data of infectious diseases with proven, potential and speculative climate sensitivity.</p>
<p>We <a href="https://onlinelibrary.wiley.com/share/7GPDVCGTDIARF2JUZ64Z?target=10.1111/1753-6405.13073">found</a> there are five climate-sensitive infectious diseases present in the region: tuberculosis, dengue, Ross River virus, melioidosis (a potentially life-threatening bacterial infection) and nontuberculous mycobacterial infection. </p>
<p>These are recorded at a greater proportion than anticipated for the population size. The Torres Strait Islands have 0.52% of Queensland’s population but over 20% of Queensland’s melioidosis cases, 2.4% of tuberculosis cases and 2.1% of dengue cases. </p>
<p><a href="https://www.nature.com/articles/s41598-019-49135-8">Tuberculosis</a> occurrence can rise with humidity, rainfall and temperature - factors exacerbated by climate change. Mosquitoes carrying <a href="https://apo.ansto.gov.au/dspace/handle/10238/2145">dengue and Ross River viruses</a> thrive with increases in temperature, rainfall, humidity and solar radiation. Increased cyclones, intense rainfall and flooding change soil conditions and elevate risk of life-threatening <a href="https://pubmed.ncbi.nlm.nih.gov/26945846/">melioidosis</a>. These same conditions can increase disease with <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4502755/">nontuberculous mycobacteria</a>. </p>
<p>The Torres Strait Islander population already experiences a higher <a href="https://www.aihw.gov.au/reports/heart-stroke-vascular-disease/cardiovascular-diabetes-chronic-kidney-indigenous/summary">burden of chronic disease</a> than the general Australian population. This raises the risk of negative health outcomes from these climate-sensitive infections even further.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/although-we-didnt-produce-these-problems-we-suffer-them-3-ways-you-can-help-in-naidocs-call-to-heal-country-163362">'Although we didn’t produce these problems, we suffer them': 3 ways you can help in NAIDOC's call to Heal Country</a>
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</p>
<hr>
<h2>Torres Strait Islander voices must be privileged in climate change responses</h2>
<p>The Torres Strait region is a part of Australia where the environmental and health impacts of climate change are being felt keenly. Torres Strait Islander voices need to be heard loudly and centrally to <a href="https://apo.org.au/sites/default/files/resource-files/2020-05/apo-nid303895.pdf">self-determine responses to protect their health and homeland</a> in the present and future.</p>
<p>Of course, localised efforts will not be sufficient in isolation. Actions to mitigate the causes of climate change and adapt to the impacts must occur in parallel nationally and globally. The Torres Strait Islands are the canary in the climate change coalmine.</p><img src="https://counter.theconversation.com/content/165388/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nina Lansbury Hall is a Lead Author on the Intergovernmental Panel on Climate Change's Assessment Report 6 and receives travel funding to attend from the Department of Foreign Affairs and Trade. She previously received funding from Queensland Health to evalaute a safe water program in the Torres Strait. </span></em></p><p class="fine-print"><em><span>Andrew Redmond, Condy Canuto, Francis Nona, and Samuel Barnes 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>Five climate-sensitive infectious diseases exist in the Torres Strait. Traditional Owners are calling on the UN for action.Nina Lansbury, Senior Lecturer, School of Public Health, The University of QueenslandAndrew Redmond, Senior Lecturer, School of Medicine, The University of QueenslandCondy Canuto, Senior Lecturer Indigenous Health. Specializing in Sexual Health, The University of QueenslandFrancis Nona, Lecturer, The University of QueenslandSamuel Barnes, Research Assistant, School of Public Health, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1608852021-05-14T18:05:13Z2021-05-14T18:05:13ZHow cables in glaciers could help forecast future sea level rise<figure><img src="https://images.theconversation.com/files/400604/original/file-20210513-21-1wruqg3.jpg?ixlib=rb-1.1.0&rect=0%2C12%2C4025%2C3005&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Greenland Ice Sheet is the world's second largest body of ice</span> <span class="attribution"><span class="source">Robert Law</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Fibre-optic cables usually make us think of ultra-fast internet – or maybe the irritation of new installation works digging up the pavement. But there are now such cables snaking their way through the centre of the planet’s second largest body of ice, the Greenland ice sheet.</p>
<p>Fibre-optic technologies are allowing us to monitor the internal structure of glaciers in unprecedented levels of detail. <a href="https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.abe7136">In our new study</a>, we show how fibre-optics are offering extraordinary new insight into how ice sheets evolve – and how the movement of Greenland’s glaciers is far more complicated than previously thought.</p>
<p>Ice loss from Greenland has <a href="https://doi.org/10.1073/pnas.1904242116">increased sixfold since the 1980s</a>, and the melting ice sheet is now the <a href="https://doi.org/10.1038/s41467-020-20011-8">single biggest contributor</a> to global sea level rise. In order to forecast the ice sheet’s future – including its worrying rates of melting – we need to understand the thermodynamic processes at work within it. That means we need to take its temperature as accurately as we can. </p>
<p>Surface conditions can be detected simply enough using satellites or <a href="https://www.businessinsider.com/greeland-ice-sheet-turned-black-melts-faster-because-of-algae-2021-3?r=DE&IR=T">in-person observations</a>, but plumbing the deepest reaches of the ice sheet, a moving block of ice a kilometre thick, is a whole different challenge.</p>
<p>This is where fibre-optics come in. In any home broadband network, information travels through fibre-optic cables as a series of light pulses. We use a similar idea in our work, firing bursts of light from a laser into a length of cable. </p>
<p>However, the cable isn’t perfectly smooth: so as the light travels, some will be reflected from tiny flaws in the cable wall, much like how light bounces off the reflective shards on a disco ball. As the cable changes temperature, or is stretched slightly by tiny earthquakes, the flaws changes: and so do the characteristics of the reflections. By continually monitoring these changes, we build up a detailed picture of what the glacier is like deep under its icy surface. </p>
<figure class="align-center ">
<img alt="A man raises a hammer above an icy tundra surrounded by equipment" src="https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400580/original/file-20210513-23-156xfs1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Taking a sledgehammer to the ice mimics seismic shockwaves.</span>
<span class="attribution"><span class="source">Adam Booth</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>As part of the EU-funded <a href="https://www.erc-responder.eu/">RESPONDER project</a> based at the <a href="https://www.spri.cam.ac.uk/">Scott Polar Research Institute</a>, University of Cambridge, we installed a kilometre-long stretch of fibre-optic cable to explore the properties of Sermeq Kujalleq, also known as Store Glacier, in West Greenland. Situated 28km from the front of the glacier, our study site creeps west at a rate of around 500 metres per year. </p>
<p>To get the cable in place, colleagues from <a href="https://www.aber.ac.uk/en/dges/research/centre-glaciology/">Aberystwyth University</a> used a hot-water drill to bore a 1,040-metre hole downwards through the ice before we threaded the cable in. The cable connects at the surface to a computer, called an interrogator, which fires and records the laser pulses. </p>
<p>Over six weeks, we monitored the cable to determine the temperature differences throughout the glacier’s layers. We also investigated ice stiffness, an indicator of how easily ice flows, by measuring variations in how quickly <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL088148">seismic vibrations</a> travel through the ice along the cable length: faster vibrations can indicate stiffer ice. For this, we made our own <a href="https://www.nature.com/articles/s43017-021-00176-6.epdf?sharing_token=0yan-HW5Qlwtkn524n42J9RgN0jAjWel9jnR3ZoTv0OwAreHKMhA7jKEtPMDxjS257nBx0-e_jzrqs7Lr8pBnLgy9pCUkVhbcrwhO5fyOv0ViYJsavEMtLn41vwpk6xbzf5jDj6Km9JFp4UzVgTXYOHnH84SmUtN90ksyxDJ7pI%3D">DIY shockwaves</a> by hitting the surface of the glacier with a sledgehammer.</p>
<figure> <img src="https://media.giphy.com/media/RUTAHot2ogFTCodPvx/giphy.gif"> <figcaption>Adam Booth makes mini earthquakes. Video by Poul Christoffersen</figcaption></figure>
<h2>The anatomy of a glacier</h2>
<p>The result is the most detailed description to date of the thermal and mechanical structure of the glacier. The internal temperature of glaciers is controlled by a few key processes. At their centre lies a core of extremely cold, stiff ice. As it continues its journey coastwards, the glacier surface is heated to -6.5°C – tropical in comparison – by sunlight and warmer air. </p>
<p>But nearest to the ground, the glacier is warmer still, as the constant churning of internal ice crystals generates heat. Add the heat naturally radiating from within the earth, and ice temperature approaches 0°C. </p>
<p>At these depths, ice coexists with small pockets of liquid water, similar to how snow becomes slush. We call such ice “temperate” and, in terms of glacier flow and eventual ice loss, it’s where the action is. That means it’s vital to understand how much temperate ice we’ve got.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=778&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=778&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=778&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=978&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=978&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400754/original/file-20210514-13-fj4wad.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=978&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Our temperature results (black line). The coldest ice is in the very centre of the ice column, heated at the surface by the atmosphere and at the bottom by the ice deforming around itself and heat radiated out from the Earth.</span>
<span class="attribution"><span class="source">Robert Law</span></span>
</figcaption>
</figure>
<p>So what did we find?</p>
<p>First, the heat map of our glacier showed far more variability than we’d expected. We found concentrated patches of heat in areas where the ice was particularly deformed, even at relatively shallow depths – something never previously observed in glacier ice. </p>
<p>Second, we observed three distinct ice layers within the glacier. Two of these were predictable. The upper 890 metres of the glacier was made of cold and stiff ice. Beneath that was older, weaker ice dating back to the last ice age. This ice is weaker because it contains particles of ice age dust, which disrupts the bonds between individual ice crystals. </p>
<figure class="align-center ">
<img alt="People stand around large equipment on an icy surface" src="https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400581/original/file-20210513-15-cq4ym.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The research team bores through the ice to install the fibre-optic cable.</span>
<span class="attribution"><span class="source">Adam Booth</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But the biggest surprise of all was hiding in the lowermost 70 metres of the glacier, where we found a large quantity of temperate ice. This might be expected in warm Alpine environments, but at such depths in Sermeq Kujalleq, the heat required to produce liquid water can only be produced by significant ice deformation: evidence of just how dynamic the base of the ice sheet is. </p>
<p>These observations not only help explain why the Greenland ice sheet is losing so much mass, they also help us predict future patterns of ice loss and sea level rise.</p><img src="https://counter.theconversation.com/content/160885/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Law receives funding from Natural Environment Research Council and European Research Council.</span></em></p><p class="fine-print"><em><span>Adam Booth does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research shows how fibre-optic cables can monitor the hidden structure of glaciers, teaching us about past and future ice flow.Robert Law, PhD candidate, University of CambridgeAdam Booth, Associate Professor in Applied Geophysics, School of Earth and Environment, University of LeedsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1518042021-01-28T13:08:18Z2021-01-28T13:08:18ZSea-level rise: writers imagined drowned worlds for centuries – what they tell us about the future<figure><img src="https://images.theconversation.com/files/381086/original/file-20210128-17-18gdk12.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3997&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/statue-liberty-sinks-ocean-1473010394">OFC Pictures/Shutterstock</a></span></figcaption></figure><p>Water was <a href="https://www.bloomberg.com/news/articles/2020-12-06/water-futures-to-start-trading-amid-growing-fears-of-scarcity">traded on Wall Street</a> alongside oil and gold for the first time in early December 2020. That might seem bizarre, but there is a grim logic at play. Reliable sources of water that have nourished civilisations throughout history – the glaciers and ice packs that release a steady flow each spring – are shrinking. <a href="https://tc.copernicus.org/articles/15/233/2021/">New research</a> has revealed that the world is losing ice 65% faster now than it did in the 1990s, at a rate of 1.3 trillion tonnes a year.</p>
<p>In works of <a href="https://theconversation.com/cli-fi-novels-humanise-the-science-of-climate-change-and-leading-authors-are-getting-in-on-the-act-51270">climate fiction</a>, depictions of environmental disaster often focus on the very property of water that has brought it to the attention of futures traders: its volatility. It has fed fantasies of flooded future worlds throughout history. But with the melting of the world’s ice sheets tracking the <a href="https://insideclimatenews.org/news/25012021/global-ice-loss-sea-level-rise/">worst-case scenarios</a> of scientists, the stories no longer seem so fantastical. A sea-level rise of two-and-a-half metres is possible by 2100, according to the estimates of the <a href="https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level#:%7E:text=Based%20on%20their%20new%20scenarios,above%202000%20levels%20by%202100.">National Oceanographic and Atmospheric Administration</a> in the US.</p>
<p>These predictions resonate with prophecies that have haunted cultures since the dawn of language. How might life be different in a drowned world? Who is responsible for the flood? And how can people alive today face this sea-soaked future? Literature is an inevitably rich guide.</p>
<h2>Conjuring the flood</h2>
<p>The story of a world-destroying flood reaches back in Judeo-Christian traditions to Noah’s ark and beyond that, to the Sumerian flood story that dates to around 2000 BC. This was passed down in hushed voices around campfires until it was recorded on Tablet XI of The Epic of Gilgamesh.</p>
<p>Floods occur in the myths of most cultures. The Ojibwe First Nations people in North America speak of The Great Serpent and the Great Flood; the story of Manu and Matsya is a Hindu flood myth; and the Welsh tale of Dwyvan and Dwyvach is an analogue for the son of Prometheus in Ancient Greek mythology, Deucalion, who survives the flood by building a large chest upon which to float.</p>
<figure class="align-center ">
<img alt="An illustration of Noah's Ark riding a huge wave." src="https://images.theconversation.com/files/381092/original/file-20210128-15-1nwljve.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381092/original/file-20210128-15-1nwljve.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381092/original/file-20210128-15-1nwljve.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381092/original/file-20210128-15-1nwljve.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381092/original/file-20210128-15-1nwljve.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381092/original/file-20210128-15-1nwljve.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381092/original/file-20210128-15-1nwljve.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">Stories of ‘the great flood’ echo throughout cultures worldwide.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/noahs-ark-middle-storm-3d-rendering-1326289805">Fer Gregory/Shutterstock</a></span>
</figcaption>
</figure>
<p>In most of these stories, the flood is the wrath of the gods (or god) on a hedonistic or godless community, though the “good” are saved. Zeus sends a flood to punish the arrogant Pelasgians; Noah is commanded to build the ark; and Lord Vishnu, disguised as the fish-like Matsya, warns the good-hearted mortal Manu of the coming waters. Our modern preoccupations with rising seas map directly onto these stories, as we assign fault for the global warming that is melting ice caps and inching the ocean up the shore.</p>
<h2>An ocean of loneliness</h2>
<p><a href="https://theconversation.com/pandemics-from-homer-to-stephen-king-what-we-can-learn-from-literary-history-133572">Apocalyptic narratives</a> have abounded for centuries, but JG Ballard’s The Drowned World was one of the first to offer a modern interpretation of a planet beset by rising seas. Set in 2145, the influence of the 1962 novel on contemporary fiction set in a deluged future is unmistakable. Ballard imagines a balmy London that’s mostly submerged, infested with giant alligators and traversed by mercenary scuba divers who plunder the city’s museums and cathedrals. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/381090/original/file-20210128-19-zsqwud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A book cover depicting a lone figure on a rooftop surrounding by vegetation and water." src="https://images.theconversation.com/files/381090/original/file-20210128-19-zsqwud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/381090/original/file-20210128-19-zsqwud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1001&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381090/original/file-20210128-19-zsqwud.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1001&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381090/original/file-20210128-19-zsqwud.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1001&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381090/original/file-20210128-19-zsqwud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1258&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381090/original/file-20210128-19-zsqwud.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1258&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381090/original/file-20210128-19-zsqwud.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1258&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 first edition cover of The Drowned World.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/The_Drowned_World#/media/File:TheDrownedWorld(1stEd).jpg">Berkley Books</a></span>
</figcaption>
</figure>
<p>The Drowned World explores the effects of human isolation, as London is emptied of all but a few die-hard survivors, soldiers and scavengers. As separate islands, the characters wallow in the loneliness that so many of us have become used to during lockdown. Not only does the sea-level rise destroy coastal cities, it also limits emotional connections between the remnant populations. With most common ground inaccessible, Ballard projects a lonelier, more violent, world.</p>
<h2>Working together</h2>
<p>Kim Stanley Robinson’s 2017 novel New York 2140 precedes Ballard’s setting by five years, but apart from depicting cities under water, the two imagined worlds couldn’t be more different. “New York is underwater but it’s better than ever,” reads <a href="https://www.newyorker.com/books/page-turner/kim-stanley-robinsons-latest-novel-imagines-life-in-an-underwater-new-york">one review</a>. </p>
<p>Robinson moves between first and third-person narration, with several sections given over to an omniscient urban historian narrator known as “the city” or “that city smartass”. These sections describe changes in the Hudson Bay area over the last millennium, from its pre-colonisation days, through the 2008 crash, the rising seas and global disasters to the “present” day of the flooded near-future. </p>
<p>This deep-time perspective suggests that individual action for environmental repair is both futile and absolutely necessary as a form of reparation. This is the <a href="https://salvage.zone/in-print/the-limits-of-utopia/">contradiction</a> of optimistic pessimism common to speculative fiction. The individual must take political action against climate disaster, or face a drowned world alone, as Ballard’s anti-hero Kerans is doomed to. </p>
<p>Robinson’s heroes are Charlotte and Inspector Gen, two middle-aged women working in refugee resettlement and policing, respectively. They live in the same cooperative housing project in Madison Square Park as Franklin, a young futures trader manipulating water commodities. His shark-like approach to trading is altered by his community-minded neighbours, who motivate him to rebel. For Robinson, individuals can only overcome if they organise.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/EQ3oKnZx088?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>And overcoming the rising seas will mean more than adjusting to flooded coasts. Some works of fiction consider how a rise in sea level will limit food production, as in Paolo Bacigalupi’s The Windup Girl. Others depict the consequences of mass migration to the remaining habitable parts of the planet, as in EJ Swift’s The Osiris Project. </p>
<p>These stories explore a sea-level rise as an existential threat to human life that’s exacerbated by the paralysis and inaction of individuals. Recent offerings of climate fiction, such as Robinson’s New York 2140 or The Ministry for the Future go further, and operate at the level of utopian imagination implicit in Ballard’s earlier dystopian vision, asking: what if we do something about it?</p><img src="https://counter.theconversation.com/content/151804/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chelsea Haith 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>Cultures worldwide are awash with tales of great floods. What can they tell us about the reality of a wetter world?Chelsea Haith, DPhil Candidate in Contemporary English Literature, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1522292020-12-23T15:25:25Z2020-12-23T15:25:25ZThe Caspian Sea is set to fall by 9 metres or more this century – an ecocide is imminent<figure><img src="https://images.theconversation.com/files/376234/original/file-20201221-23-1e59mcp.jpg?ixlib=rb-1.1.0&rect=8%2C0%2C5982%2C2991&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Anton Balazh / shutterstock</span></span></figcaption></figure><p>Imagine you are on the coast, looking out to sea. In front of you lies 100 metres of barren sand that looks like a beach at low tide with gentle waves beyond. And yet there are no tides. </p>
<p>This is what we found when we visited the small harbour of Liman, on the Caspian Sea coast of Azerbaijan. The Caspian is actually a lake, the largest in the world, and it is experiencing a devastating decline in its water level that is about to accelerate. By the end of the century the Caspian Sea will be <a href="https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.6362">nine metres to 18 metres lower</a>. That’s a depth considerably taller than most houses.</p>
<p>It means the lake will lose at least 25% of its former size, uncovering 93,000 sq km of dry land. If that new land were a country, it would be the size of Portugal.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/376052/original/file-20201220-15-mmc94t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of the Caspian Sea." src="https://images.theconversation.com/files/376052/original/file-20201220-15-mmc94t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/376052/original/file-20201220-15-mmc94t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=816&fit=crop&dpr=1 600w, https://images.theconversation.com/files/376052/original/file-20201220-15-mmc94t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=816&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/376052/original/file-20201220-15-mmc94t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=816&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/376052/original/file-20201220-15-mmc94t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1026&fit=crop&dpr=1 754w, https://images.theconversation.com/files/376052/original/file-20201220-15-mmc94t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1026&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/376052/original/file-20201220-15-mmc94t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1026&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 Caspian borders five countries and is about the size of Germany or Japan.</span>
<span class="attribution"><span class="source">Rainer Lesniewski / shutterstock</span></span>
</figcaption>
</figure>
<p>As we found in our <a href="https://www.nature.com/articles/s43247-020-00075-6">new research</a>, the crisis may well result in an ecocide as devastating as the one in the Aral Sea, a few hundred kilometres to the east. The Caspian’s surface is already dropping by <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL073958">7cm every year</a>, a trend likely to increase. In five years it might be about 40cm lower than today and in ten years almost one metre lower. Maritime countries worldwide are coming to terms with one metre or so of sea level rise by the end of the century. The Caspian Sea faces a drop of that size – except it will happen within a decade.</p>
<p>Climate change is the culprit. The Caspian Sea waters are isolated, its surface is already around 28 metres below global oceans. Its level is the product of how much water is flowing in from rivers, mostly the mighty Volga to the north, how much it rains, and how much evaporates away. </p>
<p>At the end of the century the Volga and other northern rivers will still be there. However, a projected temperature rise of about 3°C to 4°C in the region will drive evaporation <a href="https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.6362">through the roof</a>.</p>
<h2>Future misery despite past crises</h2>
<p>The Caspian Sea has a history of violent rises and falls. In Derbent, on the Caucasus coast of Russia, submerged ancient city walls testify to how low the sea was in medieval times. Around 10,000 years ago the Caspian was about 100 metres lower. A few thousand years before that it was about 50 metres higher than today and even overspilled into the Black Sea. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/376520/original/file-20201223-23-w636hm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of Caspian Sea depth." src="https://images.theconversation.com/files/376520/original/file-20201223-23-w636hm.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/376520/original/file-20201223-23-w636hm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=536&fit=crop&dpr=1 600w, https://images.theconversation.com/files/376520/original/file-20201223-23-w636hm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=536&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/376520/original/file-20201223-23-w636hm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=536&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/376520/original/file-20201223-23-w636hm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=673&fit=crop&dpr=1 754w, https://images.theconversation.com/files/376520/original/file-20201223-23-w636hm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=673&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/376520/original/file-20201223-23-w636hm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=673&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Depth map of the Caspian Sea: the areas in red and yellow may disappear entirely.</span>
<span class="attribution"><a class="source" href="https://www.researchgate.net/figure/Caspian-sea-border-and-bathymetry_fig1_316597844">Allahdadi et al (2004)</a></span>
</figcaption>
</figure>
<p>Yet people who lived beside the sea were able to overcome the swings. No human infrastructure was around to be destroyed and many animal species simply moved up and down with the sea levels, as they had done over the past 2 million years or so. But this <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025326X19302310?via%3Dihub">time is different</a>. The fall will affect the Caspian’s unique and already stressed animal and plant life, along with human societies along the coasts. </p>
<p>In some areas the coastline is about to retract hundreds of metres a year or more. Can you imagine building new piers and harbours that fast? By the time they are ready, the sea will have moved kilometres or tens of kilometres further away. Coastal promenades will soon be landlocked. The beaches of today will be the sand ridges stranded in barren plains of tomorrow. </p>
<p>The drop will also affect lowland rivers and deltas around the Caspian Sea. Once-fertile plains will become too dry for watermelon and rice farming to continue.</p>
<h2>Unique Caspian life in peril</h2>
<p>The town of Ramsar, on the Iranian coast, gave its name to a <a href="https://www.discoverwildlife.com/people/what-is-the-ramsar-convention-everything-you-need-to-know/">global wetland convention</a>. But as the sea recedes, the town is becoming landlocked and the surrounding wetlands will be gone within decades.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/376251/original/file-20201221-17-1n72aba.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A Turkmenistan stamp featuring a seal" src="https://images.theconversation.com/files/376251/original/file-20201221-17-1n72aba.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/376251/original/file-20201221-17-1n72aba.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/376251/original/file-20201221-17-1n72aba.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/376251/original/file-20201221-17-1n72aba.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/376251/original/file-20201221-17-1n72aba.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=567&fit=crop&dpr=1 754w, https://images.theconversation.com/files/376251/original/file-20201221-17-1n72aba.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=567&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/376251/original/file-20201221-17-1n72aba.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=567&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Officially listed as endangered, Caspian seal numbers have declined more than 90% over the past century.</span>
<span class="attribution"><span class="source">tristan tan / shutterstock</span></span>
</figcaption>
</figure>
<p>The shallower “shelves” of the northern and eastern Caspian are major food supplies for fish and birds, yet the entire northern and eastern shelves will transform in dry barren lands. This will devastate fish species, the Caspian seal and a richness of molluscs and crustaceans species unique to the sea. These Caspian inhabitants have already suffered badly in the past century from <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025326X19302310?via%3Dihub">pollution, poaching and invasive species</a>. About 99% of Caspian seal pups are raised on the winter ice of the north Caspian. Yet both the winter ice and indeed the whole north Caspian will disappear. </p>
<p>Remaining biodiversity hotspots in depths between <a href="https://www.sciencedirect.com/science/article/abs/pii/S0380133019302424?via%3Dihub">50 metres and 150 metres</a> will be affected as rivers dump nutrients into the deeper central basins combined with rising temperatures. This will decrease oxygen levels and developing ecological dead zones could affect the remaining refuges of Caspian species. A genuine ecocide is around the corner.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/376568/original/file-20201223-15-az199e.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing coastline in Liman, Azerbaijan, in 1995 and today." src="https://images.theconversation.com/files/376568/original/file-20201223-15-az199e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/376568/original/file-20201223-15-az199e.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=475&fit=crop&dpr=1 600w, https://images.theconversation.com/files/376568/original/file-20201223-15-az199e.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=475&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/376568/original/file-20201223-15-az199e.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=475&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/376568/original/file-20201223-15-az199e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=597&fit=crop&dpr=1 754w, https://images.theconversation.com/files/376568/original/file-20201223-15-az199e.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=597&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/376568/original/file-20201223-15-az199e.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=597&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 Caspian coastline is already receding.</span>
<span class="attribution"><span class="source">Frank Wesselingh / Google Earth</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The situation cries for action, but possibilities are limited. Rising global CO₂ levels, the main driver of climate conditions causing the Caspian crisis, can only be dealt with global agreements. In Soviet times, large scale water diversions from Siberian rivers were proposed to deal with the shrinking Aral Sea to the east. But such large works – in the case of the Caspian Sea, <a href="https://www.maritime-executive.com/editorials/the-growing-need-to-reverse-declining-caspian-sea-levels">a canal from the Black Sea</a> might be considered – come with huge ecological and geopolitical risks. </p>
<p>Yet action is necessary to safeguard the Caspian Sea’s unique plants and animals and the livelihood of the people who live around it. The stranded small harbour in Liman is further from the sea every year. If no action is taken, it will be left alone in more than one way.</p><img src="https://counter.theconversation.com/content/152229/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frank Wesselingh was coordinator of the Innovative Training Network "Drivers of Pontocaspian Biodiversity Rise and Demise" that received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 642973.</span></em></p><p class="fine-print"><em><span>Matteo Lattuada participated in the Innovative Training Network "Drivers of Pontocaspian Biodiversity Rise and Demise" that received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 642973</span></em></p>Climate change means more water is evaporating than is flowing in.Frank Wesselingh, Senior Researcher, Naturalis Biodiversity Center, Utrecht UniversityMatteo Lattuada, PhD Candidate, Department of Animal Ecology & Systematics, University of GiessenLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1435992020-07-30T19:59:53Z2020-07-30T19:59:53ZUnwelcome sea change: new research finds coastal flooding may cost up to 20% of global economy by 2100<figure><img src="https://images.theconversation.com/files/350310/original/file-20200730-25-12uwbw4.jpeg?ixlib=rb-1.1.0&rect=35%2C10%2C3390%2C2353&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Darren Pateman/AAP</span></span></figcaption></figure><p>Over the past two weeks, storms pummelling the New South Wales coast have left beachfront homes at Wamberal on the <a href="https://www.news.com.au/technology/environment/storms-leave-wamberal-oceanfront-homes-teetering-on-the-edge-of-collapse/news-story/e43edddfe2ca56a0350b7eb5ba5df2e9">verge of collapse</a>. It’s stark proof of the risks climate change and sea level rise pose to coastal areas.</p>
<p>Our new research <a href="https://www.nature.com/articles/s41598-020-67736-6">published today</a> puts a potential price on the future destruction. Coastal land affected by flooding – including high tides and extreme seas – could increase by 48% by 2100. Exposed human population and assets are also estimated to increase by about half in that time.</p>
<p>Under a scenario of high greenhouse gas emissions and no flood defences, the cost of asset damage could equate up to 20% of the global economy in 2100.</p>
<p>Without a dramatic reduction in greenhouse gas emissions, or a huge investment in sea walls and other structures, it’s clear coastal erosion will devastate the global economy and much of the world’s population.</p>
<p>In Australia, we predict the areas to be worst-affected by flooding are concentrated in the north and northeast of the continent, including around Darwin and Townsville.</p>
<figure class="align-center ">
<img alt="Man cleans up after Townsville flood" src="https://images.theconversation.com/files/350326/original/file-20200730-23-rmfjij.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350326/original/file-20200730-23-rmfjij.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350326/original/file-20200730-23-rmfjij.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350326/original/file-20200730-23-rmfjij.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350326/original/file-20200730-23-rmfjij.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350326/original/file-20200730-23-rmfjij.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350326/original/file-20200730-23-rmfjij.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A clean-up after flooding last year in Townsville, an Australian city highly exposed to future sea level rise.</span>
<span class="attribution"><span class="source">Dan Peled/AAP</span></span>
</figcaption>
</figure>
<h2>Our exposed coasts</h2>
<p>Sea levels are rising at an increasing rate for <a href="https://oceanservice.noaa.gov/facts/sealevel.html">two main reasons</a>. As global temperatures increase, glaciers and ice sheets melt. At the same time, the oceans absorb heat from the atmosphere, causing the water to expand. Seas are rising by about 3-4 millimetres a year and the rate is <a href="https://www.ipcc.ch/srocc/">expected</a> to accelerate.</p>
<p>These higher sea levels, combined with potentially more extreme weather under climate change, will bring damaging flooding to coasts. Our study set out to determine the extent of flooding, how many people this would affect and the economic damage caused.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-world-may-lose-half-its-sandy-beaches-by-2100-its-not-too-late-to-save-most-of-them-132586">The world may lose half its sandy beaches by 2100. It’s not too late to save most of them</a>
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<p>We combined data on global sea levels during extreme storms with projections of sea level rises under moderate and high-end greenhouse gas emission scenarios. We used the data to model extreme sea levels that may occur by 2100. </p>
<p>We combined this model with topographic data (showing the shape and features of the land surface) to identify areas at risk of coastal flooding. We then estimated the population and assets at risk from flooding, using data on global population distribution and gross domestic product in affected areas.</p>
<figure class="align-center ">
<img alt="Homes at Collaroy in Sydney damaged by storm surge" src="https://images.theconversation.com/files/350322/original/file-20200730-29-eqrhbr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350322/original/file-20200730-29-eqrhbr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=346&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350322/original/file-20200730-29-eqrhbr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=346&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350322/original/file-20200730-29-eqrhbr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=346&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350322/original/file-20200730-29-eqrhbr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=435&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350322/original/file-20200730-29-eqrhbr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=435&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350322/original/file-20200730-29-eqrhbr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=435&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Many coastal homes, such as these at Sydney’s Collaroy beach, are exposed to storm surge damage.</span>
<span class="attribution"><span class="source">David Moir/AAP</span></span>
</figcaption>
</figure>
<h2>Alarming findings</h2>
<p>So what did we find? One outstanding result is that due to sea level rise, what is now considered a once-a-century extreme sea level event could occur as frequently as every ten years or less for most coastal locations. </p>
<p>Under a scenario of high greenhouse gas emissions and assuming no flood defences, such as sea walls, we estimate that the land area affected by coastal flooding could increase by 48% by 2100. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/water-may-soon-lap-at-the-door-but-still-some-homeowners-dont-want-to-rock-the-boat-124289">Water may soon lap at the door, but still some homeowners don't want to rock the boat</a>
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</em>
</p>
<hr>
<p>This could mean by 2100, the global population exposed to coastal flooding could be up to 287 million (4.1% of the world’s population). </p>
<p>Under the same scenario, coastal assets such as buildings, roads and other infrastructure worth up to US$14.2 trillion (A$19.82 trillion) could be threatened by flooding. </p>
<p>This equates to 20% of global gross domestic product (GDP) in 2100. However this worst-case scenario assumes no flood defences are in place globally. This is unlikely, as sea walls and other structures have already been built in some coastal locations.</p>
<p>In Australia, areas where coastal flooding might be extensive include the Northern Territory, and the northern coasts of Queensland and Western Australia. </p>
<p>Elsewhere, extensive coastal flooding is also projected in:
- southeast China
- Bangladesh, and India’s states of West Bengal and Gujurat
- US states of North Carolina, Virginia and Maryland
- northwest Europe including the UK, northern France and northern Germany. </p>
<figure class="align-center ">
<img alt="A woman struggles through floodwaters in Bangladesh" src="https://images.theconversation.com/files/350319/original/file-20200730-35-19xjvnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350319/original/file-20200730-35-19xjvnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350319/original/file-20200730-35-19xjvnc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350319/original/file-20200730-35-19xjvnc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350319/original/file-20200730-35-19xjvnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350319/original/file-20200730-35-19xjvnc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350319/original/file-20200730-35-19xjvnc.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">Bangladesh is among the nations most exposed to coastal flooding this century.</span>
<span class="attribution"><span class="source">SOPA</span></span>
</figcaption>
</figure>
<h2>Keeping the sea at bay</h2>
<p>Our large-scale global analysis has some limitations, and our results at specific locations might differ from local findings. But we believe our analysis provides a basis for more detailed investigations of climate change impacts at the most vulnerable coastal locations. </p>
<p>It’s clear the world must ramp up measures to adapt to coastal flooding and offset associated social and economic impacts. </p>
<p>This adaptation will include building and enhancing coastal protection structures such as dykes or sea walls. It will also include coastal retreat – allowing low-lying coastal areas to flood, and moving human development inland to safer ground. It will also require deploying coastal warning systems and increasing flooding preparedness of coastal communities. This will require careful long-term planning. </p>
<p>All this might seem challenging – and it is. But done correctly, <a href="https://www.pnas.org/content/111/9/3292">coastal adaptation</a> can protect hundreds of millions of people and save the global economy billions of dollars this century.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/just-how-hot-will-it-get-this-century-latest-climate-models-suggest-it-could-be-worse-than-we-thought-137281">Just how hot will it get this century? Latest climate models suggest it could be worse than we thought</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/143599/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Young receives funding from the Australian Research Council, the Integrated Marine Observing System and the Victorian Government.</span></em></p><p class="fine-print"><em><span>Ebru Kirezci 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>In Australia, coastal flooding is expected to be worse along the northern coast in Queensland, Western Australia and the Northern Territory.Ebru Kirezci, PhD candidate, The University of MelbourneIan Young, Kernot Professor of Engineering, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1336852020-05-05T19:53:25Z2020-05-05T19:53:25Z6,000 years of climate history: an ancient lake in the Murray-Darling has yielded its secrets<figure><img src="https://images.theconversation.com/files/325471/original/file-20200405-74235-aijk4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Tom Hubble</span></span></figcaption></figure><p>For millions of years, the Murray River has flowed from the Australian Alps across the inland plains, winding through South Australia before emptying into the ocean. But the final leg of its journey once looked vastly different.</p>
<p>Our <a href="https://www.nature.com/articles/s41598-020-61800-x">research released today</a> conclusively shows what has long been suspected: 6,000 years ago, water levels in the Lower Murray River were so high that much of the system in South Australia comprised a huge lake.</p>
<p>We also uncovered an invaluable long-term record of floods and droughts in the Murray Darling Basin, by drilling deep into layers of silt and clay built up over 12,000 years.</p>
<p>Our findings point to how Australia’s most important river system might be altered by future sea level rise. What’s more, a better record of past floods and drought will help manage water use in Australia’s most important river system.</p>
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<figcaption>The Lower Murray River today and a computer-generated image of what Lake Mannum may have looked like between 5,000 and 8,500 years ago when sea levels were 2 metres higher than they are today. Original photo: Tom Hubble. Modified image: Kathirine Sentas.</figcaption>
</figure>
<h2>Probing the past</h2>
<p><a href="https://theconversation.com/scientists-hate-to-say-i-told-you-so-but-australia-you-were-warned-130211">Our climate is changing</a> and sea levels are rising.
Scientists are working hard to forecast what environments such as rivers and estuaries will look like under higher sea levels and, in Australia, <a href="https://theconversation.com/a-rare-natural-phenomenon-brings-severe-drought-to-australia-climate-change-is-making-it-more-common-133058">more intense droughts and floods</a>. </p>
<p>One way to do this is to look back to a period 5,000-8,000 years ago, to a point in the sea level cycle known as the <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0218430">Holocene highstand</a>. The Holocene refers to the past 11,700 years or so of Earth’s history. The highstand is the point at which sea levels were highest.</p>
<p>Today, the Murray River crosses into South Australia and flows within a narrow valley, then gradually widens towards Lake Alexandrina where it empties into the sea. </p>
<p>But it wasn’t always this way. After the peak of the last glacial period 18,000 years ago, melting ice caused sea levels to rise from about 120 metres below today’s level. About 6,000 years ago, sea level peaked at two metres above today’s level.</p>
<p>Researchers have previously <a href="https://www.researchgate.net/publication/262689846_Geomechanical_modeling_of_the_Murray's_Millennium_Drought_river_bank_failures_a_case_of_the_unexpected_consequences_of_slow_drawdown_soft_bank_materials_and_anthropogenic_change">hypothesised</a> that over several thousand years, the high sea level at the mouth of the Murray acted like a dam, causing water to back up in the river, creating a saltwater lake known as Lake Mannum.</p>
<p>Our research confirms that the lake existed, and that it was enormous - stretching from the mouth of the Murray to about 200 kilometres upstream near Swan Reach.</p>
<p>We used high resolution <a href="https://www.nature.com/articles/s41598-019-39516-4">two-</a> and <a href="https://www.nature.com/articles/s41598-020-61800-x">three-dimensional modelling</a> modelling of water levels and flows to confirm the presence of the lake, and how it formed.</p>
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<h2>Layers of history</h2>
<p>The naturally still waters of Lake Mannum acted as a enormous trap for clay and silt discharged upstream. Under various conditions, such as floods, the sediment travelled downstream and settled to the lake’s floor. </p>
<p>Today, the climate history for the Murray-Darling Basin is written in these sediment layers.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/330920/original/file-20200428-76598-qixf5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/330920/original/file-20200428-76598-qixf5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/330920/original/file-20200428-76598-qixf5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=2001&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330920/original/file-20200428-76598-qixf5u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=2001&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330920/original/file-20200428-76598-qixf5u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=2001&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330920/original/file-20200428-76598-qixf5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=2515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330920/original/file-20200428-76598-qixf5u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=2515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330920/original/file-20200428-76598-qixf5u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=2515&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sediment core collected near Monteith in the Lower Murray River Valley showing lots of fine layers of mud.</span>
<span class="attribution"><span class="source">Scanned core images created by Anna Helfensdorfer.</span></span>
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</figure>
<p>We collected a 30 metre-long sediment core from the present day floodplain of the Lower Murray River. </p>
<p>The core contains an 11-metre section of sediment deposited on the floor of Lake Mannum between 8,500 and 5,000 years ago. Each metre took roughly 315 years to accumulate - about three millimetres a year. </p>
<p>We believe each layer in the core probably represents an episode of increased or decreased river flow. </p>
<p>Most layers were probably produced when snow melt from the Australian Alps in spring and summer transported mud along the river system. Some layers will represent large floods that came down the Murray River, while others will represent floods that flowed down the Darling.</p>
<p>Longer-term variations in the thickness of the layers may correspond to extended periods of wetter and drier weather. </p>
<p>The next phase of our research will involve a close analysis of the sediment layers to obtain a reliable, detailed, high resolution record of flood and drought in the Murray Darling Basin.</p>
<h2>What can we learn?</h2>
<p>As sea level dropped to modern levels over the last 5,000 years, the lake slowly drained and turned back into a river.</p>
<p>These days, the lower Murray River is intensively managed. Five barrages, or barriers, have been erected near the river mouth to keep the water fresh by preventing seawater from creeping in, and to maintain water levels. Significant volumes of water have <a href="https://theconversation.com/memo-to-the-environment-minister-a-river-does-need-all-its-water-119089">been extracted</a> for irrigation and domestic use. </p>
<p>Some people argue the <a href="https://www.mdba.gov.au/river-information/running-river-murray/lower-lakes-barrages">barrages should be removed</a> to restore the natural tidal estuary and allow sea water to influence lake levels. Their removal is <a href="https://theconversation.com/the-murray-darling-basin-scandal-economists-have-seen-it-coming-for-decades-119989">unlikely</a> in the near future. But our research gives insight into what could happen if the barrages were removed, and sea levels rise under climate change.</p>
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<img alt="" src="https://images.theconversation.com/files/331718/original/file-20200430-42913-1o6p2qc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331718/original/file-20200430-42913-1o6p2qc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=341&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331718/original/file-20200430-42913-1o6p2qc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=341&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331718/original/file-20200430-42913-1o6p2qc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=341&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331718/original/file-20200430-42913-1o6p2qc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=429&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331718/original/file-20200430-42913-1o6p2qc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=429&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331718/original/file-20200430-42913-1o6p2qc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=429&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Lower Murray River near Mannum confined within the Lower Murray Gorge.</span>
<span class="attribution"><span class="source">Photo: Tom Hubble</span></span>
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<p>We expect the next step in our research, analysing the sediment cores, to provide valuable data on long-term river flows and indicate whether intense droughts, such as the Millenium drought, are more or less frequent than the once-in-a-century figure often suggested. </p>
<p>In future, water managers deciding on water allocations may benefit from knowing how much water has historically come down the system, and how often.</p><img src="https://counter.theconversation.com/content/133685/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hannah Power receives funding from the the Australian Research Council, the NSW Government under the State Emergency Management Projects program, and ship time through Australia's Marine National Facility.</span></em></p><p class="fine-print"><em><span>Anna Helfensdorfer received funding through an Australian Government Research Training Program Scholarship</span></em></p><p class="fine-print"><em><span>Tom Hubble received funding between 2013 and 2016 from South Australian Government funded Goyder Institute for Water Research for his Murray River research projects; and has been awarded ship time on RV Investigator through Australia's National Marine Facility. </span></em></p>The findings point to how Australia’s most important river system might be altered by future sea level rise.Hannah Power, Senior Lecturer in Coastal Science, University of NewcastleAnna Helfensdorfer, PhD Candidate, University of SydneyTom Hubble, Associate professor, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1325862020-03-02T19:05:09Z2020-03-02T19:05:09ZThe world may lose half its sandy beaches by 2100. It’s not too late to save most of them<figure><img src="https://images.theconversation.com/files/317964/original/file-20200302-38948-ae4dto.jpg?ixlib=rb-1.1.0&rect=28%2C661%2C4764%2C2026&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>For many coastal regions, sea-level rise is a looming crisis threatening our coastal society, livelihoods and coastal ecosystems. <a href="https://www.nature.com/articles/s41558-020-0697-0">A new study</a>, published in Nature Climate Change, has reported the world will lose almost half of its valuable sandy beaches by 2100 as the ocean moves landward with rising sea levels. </p>
<p>Sandy beaches comprise about a third of the world’s coastline. And Australia, with nearly 12,000 kilometres at risk, could be hit hard. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-antarctic-ice-melt-caused-extreme-sea-level-rise-129-000-years-ago-and-it-could-happen-again-131495">Ancient Antarctic ice melt caused extreme sea level rise 129,000 years ago – and it could happen again</a>
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<hr>
<p>This is the first truly global study to attempt to quantify beach erosion. The results for the highest greenhouse gas emission scenario are alarming, but reducing emissions leads to lower rates of coastal erosion. </p>
<p>Our best hope for the future of the world’s coastlines and for Australia’s iconic beaches is to keep global warming as low as possible by urgently reducing greenhouse gas emissions.</p>
<h2>Losing sand in coastal erosion</h2>
<p>Two of the largest problems resulting from <a href="https://www.ipcc.ch/srocc/">rising sea levels</a> are coastal erosion and an already-observed increase in the frequency of coastal flooding events.</p>
<p>Erosion during storms can have dramatic consequences, particularly for coastal infrastructure. We saw this in 2016, when <a href="https://theconversation.com/sydneys-wild-weather-shows-home-owners-are-increasingly-at-risk-60621">wild storms</a> removed sand from beaches and damaged houses in Sydney. </p>
<p>After storms like this, beaches often gradually recover, because sand from deeper waters washes back to the shore over months to years, and in some cases, decades. These dramatic storms and the long-term <a href="https://www.sciencedirect.com/science/article/abs/pii/S002532271630010X">sand supply</a> make it difficult to identify any beach movement in the recent past from sea-level rise. </p>
<p>What we do know is that the rate of sea-level rise has <a href="https://theconversation.com/contributions-to-sea-level-rise-have-increased-by-half-since-1993-largely-because-of-greenlands-ice-79175">accelerated</a>. It has increased by half since 1993, and is continuing to accelerate from ongoing greenhouse gas emissions. </p>
<p>If we continue to emit high levels of greenhouse gases, this acceleration will continue through the 21st century and <a href="https://theconversation.com/what-does-the-science-really-say-about-sea-level-rise-56807">beyond</a>. As a result, the supply of sand may not keep pace with rapidly rising sea levels. </p>
<h2>Projections for the worst-case scenario</h2>
<p>In the most recent Intergovernmental Panel on Climate Change (IPCC) <a href="https://www.ipcc.ch/srocc/">report</a>, released last year, the highest greenhouse gas emissions scenario resulted in global warming of more than 4°C (relative to pre-industrial temperatures) and a likely range of sea-level rise between 0.6 and 1.1 metres by 2100. </p>
<p>For this scenario, this new study projects a global average landward movement of the coastline in the range of 40 to 250 metres if there were no physical limits to shoreline movement, such as those imposed by sea walls or other coastal infrastructure. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-does-the-science-really-say-about-sea-level-rise-56807">What does the science really say about sea-level rise?</a>
</strong>
</em>
</p>
<hr>
<p>Sea-level rise is responsible for the vast majority of this beach loss, with faster loss during the latter decades of the 21st century when the rate of rise is larger. And sea levels will continue to rise for centuries, so beach erosion would continue well after 2100. </p>
<p>For southern Australia, the landward movement of the shoreline is projected to be more than 100 metres. This would damage many of Australia’s iconic tourist beaches such as Bondi, Manly and the Gold Coast. The movement in northern Australia is projected to be even larger, but more uncertain because of ongoing historical shoreline trends. </p>
<h2>What happens if we mitigate our emissions</h2>
<p>The above results are from a worst-case scenario. If greenhouse gas emissions were reduced such that the 2100 global temperature rose by about 2.5°C, instead of more than 4°C, then we’d reduce beach erosion by about a third of what’s projected in this worst-case scenario. </p>
<p>Current global policies would result in about <a href="https://climateactiontracker.org/global/cat-thermometer/">3°C of global warming</a>.
That’s between the 4°C and the 2.5°C scenarios considered in this beach erosion study, implying our current policies will lead to significant beach erosion, including in Australia.</p>
<p>Mitigating our emissions even further, to achieve the Paris goal of keeping temperature rise to well below 2°C, would be a major step in reducing beach loss. </p>
<h2>Why coastal erosion is hard to predict</h2>
<p>Projecting sea-level rise and resulting beach erosion are particularly difficult, as both depend on many factors. </p>
<p>For sea level, the major problems are estimating the contribution of melting Antarctic ice flowing into the ocean, how sea level will change on a regional scale, and the amount of global warming. </p>
<p>The beach erosion calculated in this new study depends on several new databases. The databases of recent shoreline movement used to project ongoing natural factors might already be influenced by rising sea levels, possibly leading to an overestimate in the final calculations. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sea-level-rise-is-inevitable-but-what-we-do-today-can-still-prevent-catastrophe-for-coastal-regions-124129">Sea level rise is inevitable – but what we do today can still prevent catastrophe for coastal regions</a>
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<h2>The implications</h2>
<p>Regardless of the exact numbers reported in this study, it’s clear we will have to adapt to the beach erosion we can no longer prevent, if we are to continue enjoying our beaches. </p>
<p>This means we need appropriate planning, such as beach nourishment (adding sand to beaches to combat erosion) and other soft and hard engineering solutions. In some cases, we’ll even need to retreat from the coast to allow the beach to migrate landward. </p>
<p>And if we are to continue to enjoy our sandy beaches into the future, we cannot allow ongoing and increasing greenhouse gas emissions. The world needs urgent, significant and sustained global mitigation of greenhouse gas emissions.</p><img src="https://counter.theconversation.com/content/132586/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Church receives funding from The Australian Research Council and the Centre for Southern Hemisphere Oceans Research (CSHOR), jointly funded by the Qingdao National Laboratory for Marine Science and Technology (QNLM, China) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO, Australia). </span></em></p>A new study has reported the world will lose almost half of its valuable sandy beaches by 2100 as sea levels rise. But cutting our emissions could keep some intact.John Church, Chair Professor, Climate Change Research Centre, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1145532019-05-06T10:36:49Z2019-05-06T10:36:49Z60 days in Iceberg Alley, drilling for marine sediment to decipher Earth’s climate 3 million years ago<figure><img src="https://images.theconversation.com/files/272054/original/file-20190501-113852-15dg0x7.JPG?ixlib=rb-1.1.0&rect=614%2C0%2C4226%2C2948&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The research vessel must dodge dangerous icebergs as it drills for sediment core samples.</span> <span class="attribution"><span class="source">Phil Christie/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Competition is stiff for one of the 30 scientist berths on the <a href="https://joidesresolution.org/">JOIDES Resolution</a> research vessel. I’m one of the lucky ones, granted the opportunity to work 12-hour days, seven days a week for 60 days as part of <a href="https://joidesresolution.org/expedition/382/">Expedition 382 “Iceberg Alley”</a> in the Scotia Sea, just north of the Antarctic Peninsula.</p>
<p><a href="https://scholar.google.com/citations?user=ruUF3z4AAAAJ&hl=en&oi=ao">I’m a geologist who specializes in paleoceanography</a>. My research focuses on how Earth’s oceans and climate operated in the past; I’m especially interested in how much and how fast the Antarctic ice sheets melted between 2.5 to 4 million years ago, the last time atmospheric carbon dioxide levels were about 400 parts per million, as they are today. This work depends on collecting sediment samples from the ocean floor that were deposited during that time. These sediment layers are like a library of the Antarctic’s past environment.</p>
<p>The JOIDES Resolution is the only ship in the world with the drilling tools to collect both soft sediment and hard rock from the ocean – material that we recover in long cylinders called cores. No wonder researchers from all over the world, at all career stages, are excited to have traveled from India, Japan, Korea, the Netherlands, Germany, Spain, Switzerland, Brazil, China, Germany, Australia, the United Kingdom and, of course, the United States to join the expedition.</p>
<h2>Fieldwork 1,000 miles (1600 km) from port</h2>
<p>Two months is actually a short amount of time in which to address scientific research questions, but there have been years of careful planning and detailed preparation in advance of this expedition. We scientists onboard make best use of our limited time by drilling at what we’ve already agreed should be the most informative locations.</p>
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<figcaption><span class="caption">An animation explains the drilling process.</span></figcaption>
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<p>When the ship arrives at the designated GPS location, the captain, the lab officer and the drilling engineer all check the position coordinates several times. With the ship’s thrusters keeping it precisely in place, workers lower coring equipment, including drill pipe, through an opening in the center of the ship. When the drill pipe reaches the coring depth – in our case ranging from 2,600 feet (800 meters) to 12,500 ft (3,800 m) – we lower a coring tool on a wireline down through the pipe.</p>
<p>Most of our cores are taken with an advanced hydraulic piston corer. In a process similar to using an elaborate cookie cutter, it punches through the ocean floor and collects a thin cylinder of the rock and sediment: our core sample. The wireline brings the 31-ft-long (9.5 m) core back to the ship. In the ship’s lab, we split the core lengthwise into an archive half – to be photographed and described – and a working half. This is the one we sample onboard for density, chemistry and magnetic properties.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.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">Co-chief scientist Michael Weber and sedimentologists (core describers) Suzanne O'Connell and Thomas Ronge examine the archive half of a split core at the describing table.</span>
<span class="attribution"><span class="source">Stefanie Brachfeld/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Today the Greenland and Antarctic <a href="https://nsidc.org/cryosphere/quickfacts/icesheets.html">ice sheets contain 99% of Earth’s fresh water</a>. If all the Antarctic ice were to melt, average sea level would rise 200 feet (60 m). This won’t happen in your lifetime. But knowing how fast an event like this can occur – based on how fast ice has melted in the past – is critical to preparing for the sea level rise already accompanying Earth’s currently warming temperatures. Helping to understand that past change is one of the goals of our work on this expedition.</p>
<p>Establishing when it was that melting glaciers originally deposited the sediments we’re collecting is crucial and difficult. Only by dating this process can we figure out how fast the ice sheets disintegrated. There are two complementary approaches that researchers have traditionally used.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.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">A microscopic fossil of diatom <em>Actinocyclus actinochilus</em>.</span>
<span class="attribution"><span class="source">Jonathan Warnock/Indiana University of Pennsylvania</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1016/j.gloplacha.2012.05.017">Paleontologists look at tiny microfossils</a> from organisms such as <a href="https://doi.org/10.1038/nature08057">diatoms</a>, <a href="https://www.radiolaria.org/">radiolaria</a> and <a href="https://www.marum.de/Karin-Zonneveld/dinocystkey.html">dinocysts</a> that are found in the sediment cores. Then they can match up the species they spot in the samples with the timeframes they were known to exist. For instance, a paleontologist might know from previous research that a particular species of diatom lived between 1.8 and 2.6 million years ago. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.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">Sediment samples, called cubes, taken for future paleomagnetic research and marked styrofoam plugs identify where samples were taken for ‘moisture and density’ (MAD) measurements.</span>
<span class="attribution"><span class="source">Stefanie Brachfeld/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>A second method of dating depends on paleomagnetists measuring the strength and direction of the sediments’ magnetism. Over Earth’s history, the magnetic field has reversed, with magnetic north flipping to point south, at irregular intervals. Scientists <a href="https://wikipedia.org/wiki/Paleomagnetism">know when the reversals occurred</a>. In the period from 1.8 to 2.6 million years ago, for example, the magnetic field flipped four times.</p>
<p><a href="https://doi.org/10.1029/2012PA002308">The paleomagnetists look for reversals</a> in the alignment of magnetic minerals in the sediment we collect, and if they find them, they <a href="https://www.researchgate.net/profile/Ted_Moore/publication/272713726_Time_is_of_the_Essence/links/569cd6ae08ae2f0bdb8beab4/Time-is-of-the-Essence.pdf">can better identify when</a>, within that 1.8 to 2.6-million-year time interval, the sediment was deposited. If reversals are not present, it might mean the sediment accumulated so fast that only one magnetic interval is represented, or that part of the sediment record is missing. To determine which possibility is more likely, they talk to the people describing the visual properties of the core to see if there are abrupt changes that might indicate a disruption in the sedimentary record.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.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">Suzanne O'Connell points out details of the core on the description table.</span>
<span class="attribution"><span class="source">Lee Stephens/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This sort of observation and consultation proceeds continuously as the cores come up and scientists work their shifts. For me, the joy of this at-sea experience is collaborating with other scientists on the same problem at the same time. If each of us was working in isolation in our own lab, collecting this much data would take years.</p>
<h2>Shipboard life</h2>
<p>Working alongside the scientists are 30 technicians who know how to operate the lab equipment, curate the hundreds of cores and keep all the computers running, and two outreach educators. All of this work is made possible by 65 people including a drilling crew, who operate the heavy equipment that collects the cores; the marine crew, who drive and maintain the ship; and the stewards who prepare the food, do the laundry and clean the ship.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.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">Loading food onto the JOIDES Resolution in Punta Arenas, Chile, to keep everyone fed during the two month expedition.</span>
<span class="attribution"><span class="source">Suzanne O'Connell/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To feed 120 people for two months, 17 pallets of food are onloaded at each port call; each grocery order includes 12,000 eggs, a ton (976 kilograms) of potatoes and 800 lbs (360 kg) of butter. There’s a full-time baker, and the cooks prepare four full meals a day and provide snacks for four coffee breaks. A small gym is available to help to offset the abundant food. On some expeditions, people run on the helipad on the ship’s stern.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.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">Humpback whales are visible right alongside the JOIDES Resolution.</span>
<span class="attribution"><span class="source">Bridget Lee/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>It’s too cold and the seas are too rough for that on this expedition. Instead, we have the thrilling opportunity to see icebergs, whales and penguins. Few places in the ocean offer such a view – but plenty of danger comes with it.</p>
<p>With drill pipe extending 10,500 ft (3,200 m) – about two miles – to the sea floor and as much as a further 2,000 feet (600 m) into the hole, we would not be able to move quickly out of the way of an approaching iceberg. It can take two hours to remove the pipe from the hole. Since the ship is attached to the drill pipe, if an iceberg were fast approaching, there might not be enough time to retrieve the drill pipe – we’d have to break the connection with explosives. Hence, there’s a strict protocol for dealing with icebergs and an experienced ice observer onboard who helps monitor the speed and direction of the nearby icebergs.</p>
<h2>A drilling program that’s grown over decades</h2>
<p>Shipboard life has changed since <a href="https://theconversation.com/scientists-have-been-drilling-into-the-ocean-floor-for-50-years-heres-what-theyve-found-so-far-100309">my first participation in the scientific ocean drilling program</a> almost 40 years ago. Back then, onboard the program’s first drill ship, the Glomar Challenger, the internet and email were not an option. To contact a person on land, an amateur radio operator on the ship would contact a shore-based shortwave radio operator who would then place a collect call to the person you wanted to speak with. If the call was accepted, you could converse, ending each part of your message with “Over” to let the recipient know it was their turn to speak. Since the entire ship could hear the conversation, as well as anyone in the world listening on the radio, it wasn’t conducive to personal communication.</p>
<p>There are many other changes onboard. Core sections are now scanned by multiple machines that improve the interpretation of the data, and new tools allow better core recovery.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=475&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=475&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=475&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=597&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=597&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=597&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Co-chief scientists Michael Weber and Maureen Raymo in the JOIDES Resolution engine room.</span>
<span class="attribution"><span class="source">Sarah Kachovich/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The most remarkable change, however, is in the composition of the scientific party. Today, half the scientists who go out are women, including the co-chief scientists – the people ultimately responsible for planning the expedition and for it reaching its scientific goals. During the entire Glomar Challenger program, from 1968 to 1983, only three of the 192 co-chief scientists were women.</p>
<p>Soon the expedition will be over, but the research will have only begun. After we’ve returned to our normal lives on land, we’ll continue to collaborate. I’ll be analyzing the size and composition of different parts of the sediment that came from land. Which parts were brought by icebergs, where did they originate, and when were they most active? How much of the sediment was transported by deep ocean currents or even by wind? Colleagues will be addressing the same questions but in the younger sediment, or determining the environmental conditions in which the microfossil communities thrived.</p>
<p>In two years, we’ll reconvene and spend several days presenting the results of our individual research. Each is a part of the larger puzzle about past climates and the rates and causes of climate change before the process was accelerated by human activity.</p><img src="https://counter.theconversation.com/content/114553/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Suzanne O'Connell receives funding from the U.S. Science Support Program, IODP, for participation in this expedition. She and her students have received funding to conduct research on prior scientific ocean drilling sediment samples, primarily from the Keck Geology Consortium, which is funded by the members schools (including Wesleyan University) and the National Science Foundation. She serves on the U.S. Advisory Committee for Scientific Ocean Drilling (USAC).</span></em></p>A paleooceanographer describes her ninth sea expedition, this time retrieving cylindrical ‘cores’ of the sediment and rock that’s as much as two miles down at the ocean floor.Suzanne OConnell, Professor of Earth & Environmental Sciences, Wesleyan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1147622019-04-04T14:23:04Z2019-04-04T14:23:04ZCyclone Idai shows why long-term disaster resilience is so crucial<figure><img src="https://images.theconversation.com/files/267287/original/file-20190403-177199-3zyuvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Flickr/ Climate Centre</span></span></figcaption></figure><p><a href="https://erccportal.jrc.ec.europa.eu/Maps/Daily-maps">Cyclone Idai</a> struck Beira, the fourth largest city in Mozambique, in mid-March with torrential rains and winds of more than 190 km per hour. It took days for the sheer size of the resulting disaster to be understood. </p>
<p>Dramatic pictures and video showed that the cyclone had left behind an inland sea up to 6 meters deep. Hundreds of people died in the storm and its immediate aftermath, and millions will be affected, potentially for <a href="https://academic.oup.com/oep/article/58/3/450/2279092">years to come</a>.</p>
<p>Increases in the frequency and intensity of extreme weather events, such as Cyclone Idai, are increasingly viewed as <a href="https://www.ipcc.ch/site/assets/uploads/sites/2/2018/07/SR15_SPM_version_stand_alone_LR.pdf">a consequence of climate change</a>. This is true globally, but particularly for areas like southern Africa. </p>
<p>Climate related disasters harm growth and development prospects. Climate change, with its more extreme weather events and rising seas, will both broaden and intensify these impacts on poor communities – and entire countries. Poor people in poor countries are most vulnerable to disasters such as Cyclone Idai. </p>
<h2>The research</h2>
<p>Just over five years ago a <a href="https://link.springer.com/article/10.1007/s10584-014-1294-x">study</a> was conducted to evaluate the effects of climate change on Mozambique. A key challenge in evaluating the implications of climate change, and thus appropriate responses, is uncertainty in what the future holds. While there’s certainty that Mozambique (along with everywhere else) will be warmer, we are much less certain about rainfall. </p>
<p>Will it rain more or less? Will the timing of rainfall change? Will rainfall come in short bursts with long dry periods in between? Will the frequency and intensity of cyclone events increase? We don’t know the answer to these questions with certainty.</p>
<p>To address this uncertainty, the study sought to expose Mozambique to the full range of potential climate futures out to 2050. Some are wetter, some are drier, some involve shifts in the timing of rainfall and others don’t. While all climate futures are warmer, some project greater or less temperature increase. By analysing the full distribution of climate outcomes, researchers could obtain a distribution of associated economic outcomes. </p>
<p>At the most negative extreme of this distribution, the study found that the economy of Mozambique may contract by up to 13% in 2050 compared with a fictional no climate change scenario – and assuming global policy fails to constrain emissions growth. These strong effects on GDP are principally the result of repeated climatic shocks. </p>
<p>To arrive at these conclusions, the study linked together a series of models that converted future weather patterns, mainly temperature and precipitation, into river flow, hydropower output, irrigation potential, flood events, crop growth and finally into economic outcomes. This was done for more than 400 future climates that were selected to reflect the best estimate of the distribution of future climates.</p>
<p>The figure below shows a distribution of the likely effects of climate change on Mozambique’s GDP around 2050 compared with a fictional, no climate change baseline, based on the results of all climate scenarios. The vertical axis shows a measure of the likelihood of the outcome. For most climate futures, climate change is likely to reduce GDP in 2050 by between 1 and 5%.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/267052/original/file-20190402-177190-1fqdaoz.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/267052/original/file-20190402-177190-1fqdaoz.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=415&fit=crop&dpr=1 600w, https://images.theconversation.com/files/267052/original/file-20190402-177190-1fqdaoz.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=415&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/267052/original/file-20190402-177190-1fqdaoz.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=415&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/267052/original/file-20190402-177190-1fqdaoz.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=521&fit=crop&dpr=1 754w, https://images.theconversation.com/files/267052/original/file-20190402-177190-1fqdaoz.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=521&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/267052/original/file-20190402-177190-1fqdaoz.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=521&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Climate change implications for GDP in Mozambique by 2050.</span>
<span class="attribution"><a class="source" href="https://link.springer.com/article/10.1007/s10584-014-1294-x">Arndt and Thurlow (2015).</a></span>
</figcaption>
</figure>
<p>The figure also shows that reductions of more than 5% of GDP by 2050 are less likely but still perfectly possible. Cyclone Idai is a good example of a low frequency but high impact extreme event. The left hand side of the distribution (the “long tail”) reflects climate futures where repeated extreme events strike economically important zones. </p>
<p>Unfortunately, it’s not clear when or where the next disaster will strike southern Africa. However, we can say that the odds are changing – and not for the better, as shown by Figure 1. </p>
<p>People living in the Beira corridor, like citizens almost everywhere, are more likely to confront more extreme climate-related disasters in the future such as droughts, floods, and cyclones. As a result, it’s important to build long-term resilience (alongside pursuing active global policies to reduce emissions and hence <a href="https://www.ipcc.ch/site/assets/uploads/sites/2/2018/07/SR15_SPM_version_stand_alone_LR.pdf">limit future climate change</a>). </p>
<h2>Way forward from Idai’s aftermath</h2>
<p>In the short term, governments and humanitarian organisations must respond quickly and robustly to Cyclone Idai. They must address both the immediate crisis and minimise the long-term adverse effects on livelihoods and development prospects of those directly affected and those impacted indirectly. </p>
<p>Many tools now exist to identify where the poorest and most affected communities are in such disasters. <a href="https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1001083">Needs location</a> and assessment combined with infrastructure restoration can generate swift responses. Social protection programmes that can be flexibly adjusted in times of disasters are also important and can dramatically improve the outlook and the futures of the people affected by such disasters, <a href="https://www.sciencedirect.com/science/article/pii/S0305750X17301092?via%3Dihub">especially the rural poor</a>.</p>
<p>Effective disaster response is particularly important for young children. If young children suffer persistent under-nutrition in the cyclone’s wake, the resulting <a href="https://books.google.ca/books?hl=en&lr=&id=aOw6DAAAQBAJ&oi=fnd&pg=PP1&dq=biesalski+1000+day&ots=xDCAqJLzE9&sig=LYubKdVHKeCrmwLdbe5EW0Ic7jc&redir_esc=y#v=onepage&q=biesalski%201000%20day&f=false">lower cognitive skills</a> will reduce lifetime earnings. In this case, the effects of Cyclone Idai would linger for generations, shaping the lives of the children and grandchildren of those who lost everything during Idai.</p>
<p>In the longer term, societies everywhere need to grapple with a warmer, more volatile, and less predictable climate, along with sea level rises that will substantially <a href="https://www.mdpi.com/2071-1050/7/6/6553">magnify the risks</a> associated with cyclone strikes such as Idai. This means: recognition of the role of extreme events as drivers of strongly negative outcomes (in, for example, <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1467-9361.2012.00673.x">infrastructure planning</a>); planning for flexibility (we don’t want to fixate on coping with a drier future when a wetter one is also quite possible or vice versa); and increased investment in win-win solutions, such as soil erosion control measures that enhance agricultural productivity while reducing river <a href="https://www.sciencedirect.com/science/article/pii/S0921818103000201">siltation </a>.</p>
<p>Finally, it calls for education, information, access to improved technologies and other resources so that an <a href="http://www.ifpri.org/blog/how-gender-shapes-responses-climate-change-new-tools-measuring-rural-womens-empowerment">empowered citizenry</a> is better prepared to confront development challenges in a context of climate change.</p><img src="https://counter.theconversation.com/content/114762/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>Cyclone Idai hit poor countries the hardest and shows why disaster resilience is a necessity.Channing Arndt, Director: Environment and Production Technology Division, International Food Policy Research Institute (IFPRI), CGIAR System OrganizationClaudia Ringler, Deputy Director, Environment and Production Technology Division, International Food Policy Research Institute (IFPRI) Licensed as Creative Commons – attribution, no derivatives.