Scientists' Concerns Challenge Conservative Sea-Level Rise Projections
The most sobering evidence of the planet's response to greenhouse gases comes from the fossil record. New evidence scientists are collecting suggests that ice sheets may be more vulnerable than previously believed, which has huge implications for sea level rise.
May 5, 2014
Yale Climate Forum
Big Story.
The East Antarctic Ice sheet – the world’s icebox, once thought all but impervious to melt on any meaningful time scale, is , on deeper inspection, much more vulnerable than we supposed. The video above, from December, fleshed that idea out.
Now, new research adds to the picture.
Climate News Network:
The East Antarctic ice sheet is thought by most scientists to be stable. But a German team says it has found how part of it could in time melt unstoppably.
LONDON, 4 May – Part of the East Antarctic ice sheet may be less stable than anyone had realised, researchers based in Germany have found.
Writing in Nature Climate Change, two scientists from the Potsdam Institute for Climate Impact Research (PIK) say the melting of quite a small volume of ice on the East Antarctic shore could ultimately trigger a discharge of ice into the ocean which would result in unstoppable sea-level rise for thousands of years ahead.http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2226.html
Their findings, which they say amount to the discovery of a hitherto overlooked source of sea level rise, appear unlikely to happen any time soon. They are based on computer simulations of the Antarctic ice flow using improved data of the ground profile beneath the ice sheet.
“East Antarctica’s Wilkes Basin is like a bottle on a slant,” said Matthias Mengel, the lead author of the study. “Once uncorked, it empties out.” The basin is the largest region of marine ice on rocky ground in East Antarctica.
The Wilkes Basin; subglacial area and model domain.
The Wilkes Basin (labelled blue shadings) is the largest region with topography below sea level in East Antarctica. At George V Coast, the Cook and Ninnis ice streams drain into the Southern Pacific Ocean and rest on deep palaeo-troughs. Our model domain (hatches) extends to the present ice divides.
At the moment a rim of ice at the coast holds the ice behind it in place, like a cork holding back the contents of a bottle. The air over Antarctica remains cold, but oceanic warming can cause the ice on the coast to melt. This could make the relatively small “cork” disappear.
Once it had gone, the result would be a long-term sea level rise of three to four metres. “The full sea-level rise would ultimately be up to 80 times bigger than the initial melting of the ice cork,” says the study’s co-author, Anders Levermann. “Until recently, only West Antarctica was considered unstable, but now we know that its ten times bigger counterpart in the East might also be at risk.”
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