Researchers believe coastal glaciers in West Antarctica may have reached a tipping point of "unstoppable" retreat as warming ocean waters melt them from below, threatening possible devastating sea level rises.
There is enough ice in the glaciers in the region to push global sea levels up by more than 10 feet if they all melted, the scientists say.
Computer models suggest that just small amounts of melting in the coming decades could destabilize the entire ice sheet on the western part of the frozen continent, researchers at the Potsdam Institute for Climate Impact Research in Germany say in a new study.
The focus of their concern is two vulnerable glaciers in the Amundsen Sea region—the Thwaites and the Pine Island glaciers—where destabilization could trigger a collapse of the entire West Antarctic ice sheet and trigger resulting catastrophic sea level rises.
The model shows that if melting continues for just a few decades it could result in "thousands of years of ice motion," says study co-author Anders Levermann.
That's because if the glaciers in the Amundsen Sea region are destabilized, it would allow warm seawater to erode neighboring ices shelves, setting off a domino effect on the continent's ice sheet, experts suggest.
"This paper does confirm what we hypothesized, that knocking out the Pine Island Glacier and Thwaites takes down the rest of the West Antarctic Ice Sheet," says Ian Joughin, a glaciologist at the University of Washington, Seattle, who co-authored a study appearing last year in Science on the retreat of the Thwaites Glacier.
The Thwaites and Pine Island glaciers are the fastest-melting streams of ice on the entire Antarctic continent. The Thwaites glacier is the largest in the region, covering more area than the state of Pennsylvania and a mile thick in some places.
If those glaciers continue to retreat, they could set in motion a process without a foreseeable end, researchers say.
"We showed that there is actually nothing that stops it," says Levermann. "There are troughs and channels and all this stuff, there's a lot of topography that actually has the potential to slow down or stop the instability, but it doesn't."
Sea level rises suggested by the research would impact every area of the globe; it is estimated around 150 million people live within just 3 feet of elevation above current sea levels.
If sea levels rose 10 feet, many U.S. East Coast cities such as New York and Miami would be inundated, experts say.