*[Enwl-eng] Melting West Antarctica: 'we've lost control'
ENWL
|
No images? Click here  The melting of Earth's largest volume of land-based ice this century is now beyond humanity's control, according to a new study. Even if global heating can be halted at 1.5°C, the West Antarctic ice sheet will melt three times faster than the historical rate, with dire consequences for coastal communities worldwide. You're reading the Imagine newsletter – a weekly synthesis of academic insight on solutions to climate change, brought to you by The Conversation. I'm Jack Marley, energy and environment editor. This week, we're discussing the implications of new research on West Antarctica for sea-level rise this century. "How do you tell a bad news story?" Kaitlin Naughten asks. Naughten is an ocean-ice modeller at the British Antarctic Survey and led the recent ice sheet research with Jan De Rydt (Northumbria University) and Paul Holland (British Antarctic Survey). "The conventional wisdom is that you’re supposed to give people hope: to say that there’s a disaster behind one door, but we can avoid it if only we choose a different one. What do you do when your science tells you that all doors lead to the same disaster?" Naughten and her colleagues ran simulations of the 21st century on a supercomputer. Each one compared temperature rises and ice-shelf melting in the Amundsen Sea around western Antarctica up to 2100, varying by the amount of fossil fuels burned and natural variations in the climate, like the timing of El Niño. Their results indicate that substantial melting of West Antarctica is guaranteed this century, regardless of how quickly the world eliminates the fossil fuels driving climate change. What this will mean for sea-level rise is more complicated. In order to accurately predict how much of the world's coastline will be flooded, their model would also need to simulate the flow of Antarctica's glaciers and the accumulation of snow on the vast ice sheet covering the frozen continent. Even without that information, Naughten and her colleagues believe that their findings imply a rapid acceleration of sea-level rise. "The West Antarctic ice sheet is already contributing substantially to global sea-level rise and is losing about 80 billion tonnes of ice a year," the team says. "It contains enough ice to cause up to 5 metres of sea-level rise, but we don’t know how much of it will melt, and how quickly." It's bad news, but that shouldn't induce despair, they caution. Their study considered changes to the West Antarctic ice sheet up to 2100 – but the future doesn't end there. "Our simulations of the 1.5°C scenario show ice-shelf melting starting to plateau by the end of the century, suggesting that further changes in the 22nd century and beyond may still be preventable. Reducing sea-level rise after 2100, or even slowing it down, could save many coastal cities." Save the living coast Neil Saintilan has studied coastal wetlands for more than 20 years. These are habitats on land which are inundated by tides, including the wooded mangrove swamps of the tropics and the grassy marshes of colder climes. He is a professor of environmental science at Macquarie University in Australia. "Much of the world’s natural coastline is protected by living habitats," Saintilan says. "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." Wetlands have been mistreated for much of human history. A review published earlier this year found that one-fifth of them were dug up, drained and converted to farms or dwellings over the last three centuries. "Losing a wetland a few acres in size may not sound much on a global or even national scale, but it’s very serious for the nearby town that now floods when it rains and is catastrophic for the specialised animals and plants, like curlews and swallowtail butterflies, living there," says Christian Dunn, a wetland ecologist at Bangor University. The review also contained some good news: much less wetland area has been lost globally than scientists once thought. If allowed to recover, these habitats could buffer coastal communities from surging tides and storms, stall floods, delay droughts and draw down more of the atmospheric carbon fuelling climate change. But what is in store for coastal wetlands as sea levels rise? A study published in 2019 suggested that they might become even more useful in resisting the upwards climb of Earth's temperature. Already credited with storing the most carbon of all ecosystems, coastal wetlands can adapt to sea-level rise as they have in the past: by raising their soil level and developing denser roots capable of trapping even more carbon-rich sediment, the paper argued. Sounds promising, but Saintilan warns that it would be unwise to overstate the resilience of these ecosystems. As part of an international team, he used computer modelling to predict the fate of 90 mangroves, 477 tidal marshes and 872 coral reef islands worldwide in a recently published report. Their analysis drew on geological records of coastal habitats to understand how they responded to sea-level rise following the last Ice Age, as well as contemporary surveys and satellite imagery. "We found most tidal marshes and mangroves are keeping pace with current rates of sea-level rise, around 2–4mm per year," he says. But in some parts of the world, the land is subsiding. This has doubled the rate of sea-level rise in some areas, offering a glimpse of what coastal wetlands will face if warming exceeds 1.5°C. "They are slowly drowning and in some cases, breaking up," Saintilan says. Warming of up to 2°C could cause seas to rise up to 8mm a year, at which it becomes "very likely" coastal wetlands will no longer keep pace. Roads and buildings may make a landward retreat impossible and doom many of these vital habitats to extinction he adds. "There are some consequences of climate change that can no longer be avoided, no matter how much fossil fuel use falls," Naughten says. In the face of such defeat, she urges people to be brave and to recognise that greater damage can still be prevented. "Courage means accepting the need to adapt, protecting coastal communities where it’s possible to do so, and rebuilding or abandoning them where it’s not." - Jack Marley, Environment commissioning editor Was this email forwarded to you? Join the 20,000 people who get one email every week about the most important issue of our time. Subscribe to Imagine.  Increasing melting of West Antarctic ice shelves may be unavoidable – new research Humanity has lost control of West Antarctic ice-sheet melting.  We studied more than 1,500 coastal ecosystems - they will drown if we let the world warm above 2°C 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.  Earth has lost one-fifth of its wetlands since 1700 – but most could still be saved The swamp has not yet been drained everywhere.  Rising seas allow coastal wetlands to store more carbon One surprising potential benefit of sea-level rise is it helps coastal wetlands store more carbon.  What will happen to the Greenland ice sheet if we miss our global warming targets The ice will survive if temperatures are soon brought back down – new study.  The sea isn’t actually ‘level’: why rising oceans will hit some cities more than others At 2°C of warming and beyond, many megacities will have to cope with an increased flood risk. Reader comment of the week 💬
Bill Lang Latest from The Conversation on climate change
From: Imagine newsletter
Sent: Wednesday, October 25, 2023 9:02 PM
Subject: Melting West Antarctica: 'we've lost
control' |
------------- * ENWL * ------------
Ecological North West Line * St. Petersburg, Russia
Independent Environmental Net Service
Russian: ENWL (North West), ENWL-inf (FSU), ENWL-misc (any topics)
English: ENWL-eng (world information)
Send information to en...@enw.net.ru
Subscription,Moderator: en...@enw.net.ru
Archive: http://groups.google.com/group/enwl/
New digests see on https://ecodelo.org
(C) Please refer to exclusive articles of ENWL
-------------------------------------