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East Antarctic Ice Sheet is less stable than previously thought

It has been long believed that the East Antarctic Ice Sheet is much more resilient than the ice cover of West Antarctica and Greenland, but new research has revealed that the ice sheet is actually much less stable than was previously thought.

The East Antarctic Ice Sheet, which stores more water than any other ice sheet on the planet, holds enough water to raise sea levels by an estimated 174 feet.

Researchers from the University of Texas at Austin and the University of South Florida collected geophysical and geological data for an unprecedented survey of East Antarctica’s Sabrina Coast.

They ultimately discovered that the East Antarctic Ice Sheet has a long history of expanding and shrinking, which means that ice cover in this area could make a substantial contribution to sea level rise as global temperatures rise.

In fact, the glaciers in this region may be particularly vulnerable due of their location in the Aurora Basin, a region of East Antarctica that mostly lies below sea level.

Study co-author Sean Gulick said the research revealed that glaciers from the Aurora Basin have been stable only for the past few million years.

“It turns out that for much of the East Antarctic Ice Sheet’s history, it was not the commonly perceived large stable ice sheet with only minor changes in size over millions of years,” said Gulick. “Rather, we have evidence for a very dynamic ice sheet that grew and shrank significantly between glacial and interglacial periods. There were also often long intervals of open water along the Sabrina Coast, with limited glacial influence.”

According to the analysis, ice advanced from the Aurora Basin and retreated back again at least 11 times during the first 20 million years of the ice sheet’s history.

Researchers also discovered that the ice sheet was previously much more wet than it is today, with meltwater from the surface flowing into a network of channels underneath the ice. This phenomenon occurred when atmospheric temperatures and CO2 levels were similar to what they are today.

“We shouldn’t view this as one ice sheet that suddenly grew to its present size, but rather one that was a transient ice sheet that expanded every couple million years or so,” said Gulick.

Approximately 6 million years ago, the East Antarctic Ice Sheet stopped producing large volumes of meltwater when it expanded and stabilized. The researchers warn that global warming could cause the East Antarctic glaciers to start melting, making the ice sheet unstable again.

Study co-lead author Amelia Shevenell said that the warm ocean water currently melting East Antarctica’s largest glacier, the Totten Glacier, could be an early warning of things to come.

“A lot of what we are seeing right now in the coastal regions is that warming ocean waters are melting Antarctica’s glaciers and ice shelves, but this process may just be the beginning,” said Shevenell. “Once you have that combination of ocean heat and atmospheric heat — which are related — that’s when the ice sheet could really experience dramatic ice mass loss.”

The research is published in the journal Nature.

By Chrissy Sexton, Staff Writer

Image Credit: Sean Gulick/University of Texas at Austin

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