WASHINGTON (dpa-AFX) - A new study finds that continued growth in greenhouse-gas emissions over the next several decades could trigger an unstoppable collapse of Antarctica's ice - raising sea levels by more than a meter by 2100 and more than 15 meters by 2500.
'That is literally remapping how the planet looks from space,' says study co-author Rob DeConto, a geoscientist at the University of Massachusetts Amherst. The good news, he says, is that it projects little or no sea-level rise from Antarctic melt if greenhouse-gas emissions are reduced quickly enough to limit the average global temperature rise to about 2 °C.
The findings of the study, published online this week in Nature, add to a growing body of research that suggests that Antarctic ice is less stable than once thought.
In its 2013 report, the Intergovernmental Panel on Climate Change estimated that Antarctic melting would contribute just a few centimeters to sea-level rise by 2100. But as scientists develop a better understanding of how the ocean and atmosphere affect the ice sheet, their projections of the continent's future are growing more dire.
DeConto and co-author David Pollard, developed a climate model that accounts for ice loss caused by warming ocean currents - which can eat at the underside of the ice sheet - and for rising atmospheric temperatures that melt it from above. Ponds of meltwater that form on the ice surface often drain through cracks; this can set off a chain reaction that breaks up ice shelves and causes newly exposed ice cliffs to collapse under their own weight.
'Once the ocean warms up, that ice will not be able to recover until the oceans cool back down,' a process that could take thousands of years, DeConto says.
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