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'Doomsday' glacier could melt faster than previously thought

A new study of Thwaites Glacier suggests it might retreat at twice its recent rate in the future, threatening to cause a substantial rise in sea level.
Antarctica's Thwaites Glacier has the potential to add several inches to global sea levels.James Yungel / NASA

One of the most closely watched glaciers in the world could soon melt faster than expected, a shift that could lead to sudden rises in sea levels.

Antarctica's Thwaites Glacier, sometimes called the "doomsday" glacier for the consequences that could result as it continues to melt, is capable of shrinking twice as fast as it has in recent years, according to a study published Monday in the journal Nature Geoscience.

The study looked to the body's past movement to predict how it could move in the future. The findings were based on the Thwaites Glacier’s imprints on the seabed, allowing researchers to track the glacier's movements along the seabed from up to a century ago. Satellite imaging up to now has provided the glacier's movements dating back only around 30 years.

Researchers found the glacier was shrinking at over 1.3 miles per year around 100 years ago, twice as fast as its movements from 2011 to 2019.

"About 100 years ago, it retreated faster than it is currently retreating. … You could say that’s good news, because it’s not so bad now compared to what it was in the past,” said a co-author of the study, Anna Wåhlin, a professor of physical oceanography at Sweden’s Gothenburg University. “But you can also say that it’s bad news, because it could happen again.”

Researchers fear the glacier’s retreat will soon melt past a ridge on the seabed and reach a large ice-filled basin inland, where the added volume of ice means the retreating glacier will contribute more to rising sea levels.

“Thwaites ticks several boxes of a glacier that might be experiencing a faster retreat in the future: It is retreating back into a deeper basin; it is in contact with warm ocean currents; it has a very large catchment area that stores large amounts of ice,” Wåhlin said.

Thwaites Glacier, one of Antarctica's largest, equal to about the size of Florida, accounts for only around 5% of Antarctica's contributions to the world's sea-level changes.

But previous studies suggested the ice shelf might collapse into the ocean as soon as 2031. The collapse of the entire glacier into the oceans could cause the world's oceans to rise by up to 2 feet. Its future behavior has been closely studied, and it is considered a bellwether for the consequences of climate change.

"Exactly how big a threat there is is unfortunately still difficult to answer — but the fact that we finally have a data point that the models can tie back to is an important part of the puzzle," Wåhlin said.