The largest glacier in East Antarctica, containing ice equivalent to a six-metre (20-foot) rise in global sea levels, is melting due to warm ocean water, Australian scientists said on Monday.
The 120-kilometre (74.4 mile) long Totten Glacier, which is more than 30 kilometres wide, had been thought to be in an area untouched by warmer currents.
But a just-returned voyage to the frozen region found the waters around the glacier were warmer than expected and likely melting the ice from below.
"We knew that the glacier was thinning from the satellite data, and we didn’t know why," the voyage’s chief scientist Steve Rintoul told AFP.
He said that up until recently the East Antarctica ice sheet had been thought surrounded by cold waters and therefore very stable and unlikely to change much.
But the voyage found that waters around the glacier were some 1.5 degrees Celsius warmer than other areas visited on the same trip during the southern hemisphere summer.
"We made it to the front of the glacier and we measured temperatures that were warm enough to drive significant melt," Rintoul said.
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