West Antarctic’s Sea-Level Rise May Be Overstated, Study Shows

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West Antarctic?s Sea-Level Rise May Be Overstated, Study Shows - Bloomberg.com

 

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May 15 (Bloomberg) -- The collapse of the West Antarctic Ice Sheet would contribute 3.3 meters (11 feet) to the rise in sea levels over hundreds of years, about half as much as previous estimates, a U.K.-led team of researchers found.   Disintegration of the floating ice shelves surrounding the sheet, which is grounded, would open the way to melting, the researchers, led by Jonathan Bamber, a glaciologist at the University of Bristol, said today in the journal Science. That melting would lead to a rise in sea levels that’s much less than scientists estimated, Bamber said.   “There’s a vast body of research that’s looked at the likelihood of a West Antarctic Ice Sheet collapse and what implications such a catastrophic event would have for the globe,†Bamber said in a statement. “All of these studies have assumed a 5-meter to 6-meter contribution to sea-level rise. Our calculations show those estimates are much too large.†  Bamber’s team said that while tracts of ice grounded below sea level would float upwards and break up if the ice shelves holding them disintegrated, portions of ice attached to land above sea level will stay frozen, contrary to earlier estimates.   Antarctica is divided into two main ice sheets: east and west. The continent as a whole holds enough ice to raise sea levels by 57 meters, the United Nations Intergovernmental Panel on Climate Change says. While the larger eastern sheet is largely stable, glaciers on the western sheet have accelerated their flow in recent years amid global warming and ice shelves surrounding it have broken up.   The western ice sheet’s contribution to sea-level rise won’t be uniform across the globe, Bamber’s team also found, noting that because of gravitational effects, the Indian Ocean and the U.S. Pacific and Atlantic coasts would have more sea- level rise than the rest of the world.   “The pattern of sea-level rise is independent of how fast or how much of the West Antarctic Ice Sheet collapses,†Bamber said. “Even if the WAIS contributed only a meter of sea level rise over many years, sea levels along North America’s shorelines would still increase 25 percent more than the global average.â€