'Doomsday glacier' is melting faster than thought, study finds

A glacier in Antarctica the size of Florida that could dramatically raise global sea levels is disintegrating faster than previously predicted, according to a study published Monday in the journal Nature Geoscience.

A group of international researchers mapped the historical footprint of western Antarctica’s Thwaites Glacier — nicknamed the “doomsday glacier” because of the massive impact its collapse due to warmer temperatures would have. They found “exceptionally fast rates of past retreat,” including — at some point in the last two centuries — a period in which the glacier fell back by 1.3 miles per year. That’s twice as fast as the rate of retreat that had been found in the 2010s.

“Thwaites is really holding on today by its fingernails, and we should expect to see big changes over small time scales in the future — even from one year to the next — once the glacier retreats beyond a shallow ridge in its bed,” British Antarctic Survey’s Robert Larter, a co-author of the study, said in a news release that accompanied the study’s publication.

The reverberations of that melting could be huge, according to the scientists involved in the research. “You can’t take away Thwaites and leave the rest of Antarctica intact,” said Alastair Graham, a marine geologist at the University of South Florida and a co-author of the study.

The Thwaites Glacier is one of the widest on Earth, but it’s just a small piece of the West Antarctic Ice Sheet, which contains enough ice to raise sea level by up to 16 feet if it were to melt, according to NASA.

Thwaites is grounded in the ocean floor, rather than land, making it especially prone to melting due to warming waters. In 2020, scientists found that warm water was melting Thwaites’s lower reaches. Studies previously have shown that up to 90% of the warming caused by greenhouse gas emissions is absorbed by the oceans and that oceans are warming faster than previously thought.

Thwaites’s melting already accounts for about 4% of annual sea level rise, which is currently about 0.12 to 0.14 inches per year, according to the Environmental Protection Agency. More than 40% of the world’s human population live within 60 miles of the coast, many in areas that would be inundated by sea level rise of more than 3 feet.

This is not the first warning sign that Thwaites may be in a precarious state thanks to rising global temperatures. Satellite images taken late last year show that an ice shelf in the eastern portion of the glacier is showing signs of cracking.

“Things are evolving really rapidly here,” Ted Scambos, a glaciologist at the University of Colorado Boulder and a leader of the International Thwaites Glacier Collaboration, told reporters at the time. “It’s daunting.”

Researchers involved in that study warned that the ice shelf might become unmoored from the sea floor, which could lead to ice cliff collapse, a process that would then trigger more melting. “It would become self-sustaining and cause quite a bit of retreat for certain glaciers” including Thwaites, said Anna Crawford, a glaciologist at the University of St. Andrews, at the time of that study’s release.

Graham said that his team could not confidently predict whether the Thwaites Glacier will entirely dissolve, but that reducing emissions will be crucial to reducing the risk.

“Right now, we can do something about it — especially if we can stop the ocean from warming,” he said.