region:west antarctica

UK, U.S. study Antarctic glacier, hoping to crack sea level risks | Agricultural Commodities | Reuters
▻https://af.reuters.com/article/commoditiesNews/idAFL8N1S72CG

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Britain and the United States launched a $25 million project on Monday to study the risks of a collapse of a giant glacier in Antarctica that is already shrinking and nudging up global sea levels.

The five-year research, involving 100 scientists, would be the two nations’ biggest joint scientific project in Antarctica since the 1940s. Ice is thawing from Greenland to Antarctica and man-made global warming is accelerating the trend.

The scientists would study the Thwaites Glacier, which is roughly the size of Florida or Britain, in West Antarctica, the UK Natural Environment Research Council and U.S. National Science Foundation said in a joint statement.

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Study shows Thwaites Glacier’s ice loss may not progress as quickly as thought
▻https://phys.org/news/2017-06-thwaites-glacier-ice-loss-quickly.html

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East Antarctic icesheet unsettles science
▻http://us6.campaign-archive2.com/?u=6e13c74c17ec527c4be72d64f&id=b145258428&e=08052803c8

East Antarctic icesheet unsettles science

Scientists now believe that the East Antarctic ice sheet could become unstable, a discovery with potentially serious global implications.

By Tim Radford

LONDON, 17 December, 2016 – East Antarctica, the supposedly stable sheet of ice that makes up the greater part of the Southern Continent, may not be so stable after all. Scientists from the Netherlands have identified a mechanism that can trigger melting deep in the huge ice shelf.

And an international team of researchers has found that the planet’s single greatest body of ice is not just vulnerable to disintegration, but has played a dynamic role in natural climate change for at least 8,000 years.

The continent carries most of the world’s fresh water in the form of ice: if it all melted, sea levels would rise by 60 metres or more. But the process would take millennia and anyway, the latest research does not suggest that the East Antarctica ice sheet is unstable: just that, like the fast-warming West Antarctica region, it could become unstable.

#climat #antarctique #arctique #it_has_begun

NASA Study: Mass Gains of Antarctic Ice Sheet Greater than Losses | NASA
▻https://www.nasa.gov/feature/goddard/nasa-study-mass-gains-of-antarctic-ice-sheet-greater-than-losses

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A new NASA study says that an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.

The research challenges the conclusions of other studies, including the Intergovernmental Panel on Climate Change’s (IPCC) 2013 report, which says that Antarctica is overall losing land ice.

According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed  to 82 billion tons of ice per year between 2003 and 2008.

“We’re essentially in agreement with other studies that show an increase in ice discharge in the Antarctic Peninsula and the Thwaites and Pine Island region of West Antarctica,” said Jay Zwally, a glaciologist with NASA Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study, which was published on Oct. 30 in the Journal of Glaciology. “Our main disagreement is for East Antarctica and the interior of West Antarctica – there, we see an ice gain that exceeds the losses in the other areas.” Zwally added that his team “measured small height changes over large areas, as well as the large changes observed over smaller areas.”

Scientists calculate how much the ice sheet is growing or shrinking from the changes in surface height that are measured by the satellite altimeters. In locations where the amount of new snowfall accumulating on an ice sheet is not equal to the ice flow downward and outward to the ocean, the surface height changes and the ice-sheet mass grows or shrinks.

But it might only take a few decades for Antarctica’s growth to reverse, according to Zwally. “If the losses of the Antarctic Peninsula and parts of West Antarctica continue to increase at the same rate they’ve been increasing for the last two decades, the losses will catch up with the long-term gain in East Antarctica in 20 or 30 years — I don’t think there will be enough snowfall increase to offset these losses.”

The U.S. has caused more global warming than any other country. Here’s how the Earth will get its revenge. - The Washington Post
▻http://www.washingtonpost.com/news/energy-environment/wp/2015/01/22/the-u-s-has-contributed-more-to-global-warming-than-any-other-countr

Namely: If West Antarctica collapses entirely — a process that would likely play out over centuries, but that could substantially begin in this one – the expected 11 feet of sea level rise won’t just spread out evenly across the ocean. The United States will actually get a lot more sea level rise than many other parts of the world — possibly over 14 feet. Call it geophysical karma — we’re the nation most responsible for global warming and, at least in this particular case, we’ll get more of the consequences.

#climat #Etats-Unis #antarctique

A Huge Antarctic Ice Sheet Is Melting Three Times Faster Than Previously Thought | ThinkProgress
▻http://thinkprogress.org/climate/2014/12/03/3598719/amundsen-sea-ice-melt

A West Antarctic ice sheet that is roughly the size of Texas is losing the amount of ice equivalent to Mount Everest every two years, representing a melt rate that has tripled over the last decade, according to new research to be published in the journal Geophysical Research Letters on Friday.

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Greenland ice may melt even faster | Climate News Network

▻http://www.climatenewsnetwork.net/2014/05/greenland-ice-may-melt-even-faster

By Tim Radford

Research scientists discover that the vulnerability of Greenland’s glaciers to global warming is much greater than feared, increasing the threat of rising sea levels around the globe

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LONDON, 24 May − Just days after US researchers identified geophysical reasons why West Antarctica’s glaciers are increasingly vulnerable to global warming, a partner team has pinpointed a related cause for alarm in Greenland.

Many of the bedrock crevices and canyons down which the island’s glaciers flow have basements that are below sea level. This means that as warm Atlantic waters hit the glacier fronts, the glaciers themselves become more vulnerable to global warming and increasingly likely to melt at a faster rate.

#climat #arctique #groenland

Scientists Warn of Rising Oceans From Polar Melt - NYTimes.com

▻http://www.nytimes.com/2014/05/13/science/earth/collapse-of-parts-of-west-antarctica-ice-sheet-has-begun-scientists-say.htm

A large section of the mighty West Antarctica ice sheet has begun falling apart and its continued melting now appears to be unstoppable, two groups of scientists reported on Monday. If the findings hold up, they suggest that the melting could destabilize neighboring parts of the ice sheet and a rise in sea level of 10 feet or more may be unavoidable in coming centuries.

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Global warming caused by the human-driven release of greenhouse gases has helped to destabilize the ice sheet, though other factors may also be involved, the scientists said.

#climat

#Antarctic lake mission reports historic breakthrough
▻http://blogs.nature.com/news/2013/01/antarctic-lake-mission-reports-historic-breakthrough.html

At 05.00 a.m. local time, the WISSARD (Whillans Ice Stream Subglacial Access Research Drilling) field team hit the shallow waters of Lake Whillans, a small subglacial lake beneath 800 metre-thick ice at the margin of the West Antarctica’s Ice Sheet.
(...)
At merely 60 square kilometres size, Lake Whillans is a comparatively small lake. But scientists hope that its environs do hold clues to the history of Antarctica’s glaciers and to the kind of life that may exist in these extreme environments.

#vostok #recherche #vie