Part of East Antarctica is more vulnerable than expected to a thaw that could trigger an unstoppable slide of ice into the ocean and raise world sea levels for thousands of years, a study showed on Sunday.
The Wilkes Basin in East Antarctica, stretching more than 1,000 km (600 miles) inland, has enough ice to raise sea levels by 3 to 4 metres (10-13 feet) if it were to melt as an effect of global warming, the report said.
The Wilkes is vulnerable because it is held in place by a small rim of ice, resting on bedrock below sea level by the coast of the frozen continent. That "ice plug" might melt away in coming centuries if ocean waters warm up.
"East Antarctica's Wilkes Basin is like a bottle on a slant. Once uncorked, it empties out," Matthias Mengel of the Potsdam Institute for Climate Impact Research, lead author of the study in the journal Nature Climate Change, said in a statement.
Co-author Anders Levermann, also at Potsdam in Germany, told Reuters the main finding was that the ice flow would be irreversible, if set in motion. He said there was still time to limit warming to levels to keep the ice plug in place.
Almost 200 governments have promised to work out a U.N. deal by the end of 2015 to curb increasing emissions of man-made greenhouse gases that a U.N. panel says will cause more droughts, heatwaves, downpours and rising sea levels.