Why 'unavoidable' melting at Antarctica's 'Doomsday Glacier' could be catastrophic

Melting in West Antarctica, a region which includes the "Doomsday Glacier" that threatens the globe with severe sea level rise, could be inevitable in the future due to warming oceans, scientists say.

Loss of ice in West Antarctica has been prevalent this year. In February, Antarctica sea ice reached a record low. In October, the ozone hole over Antarctica grew to one of the largest on record.

Future increases in ice-shelf melting in the West Antarctic could be "unavoidable" due to rapid ocean warming, according to models published Monday in Nature Climate Change.

Antarctic researchers set out to determine how much melting could still be prevented by controlling greenhouse gas emissions, and how much melting was already "committed," Kaitlin Naughten, an ocean modeller at the British Antarctic Survey specializing in ice shelf, ocean and sea ice interactions, and one of the authors of the paper, told reporters during a press briefing on Thursday.

"Unfortunately, it’s not great news," Naughten said. "Our simulations suggest we are now committed to a rapid increase in the rate of ocean warming and ice shelf melting for the rest of the century."

The researchers found that, under a range of mitigation scenarios, climate change could cause the ocean to warm at three times the historical rate -- even in the best-case scenario -- indicating that mitigation efforts may have limited power to slow ocean warming in the Amundsen Sea in the coming decades.

Unavoidable melting occurred in both worst-case and best-case scenarios, in which the most ambitious goal of the Paris Climate Agreement, limiting global warming to 1.6 degrees Celsius since the Industrial Revolution, are met.

"There was little to no difference between the scenarios," Naughten said.

The West Antarctic region includes Thwaites, a glacier located in the Amundsen Sea that is one of the largest contributors to sea level rise from Antarctica, in addition with Pine Island. Thwaites, a glacier the size of Florida known for its rapid retreat, is also known as the "Doomsday Glacier" because its melting could cause global sea levels to rise by about 10 feet, according to climate scientists.

The study did not directly simulate sea level rise from the projected melting in West Antarctica, but researchers "have every reason to suspect" that sea level rise would occur as ice loss from the region enters the ocean, Naughten said.

"It appears that we may have lost control of the West Antarctic ice shelf melting over the 21st century," Naughten said.

Since ice shelves play an important role in buttressing, the slowing of flow of glaciers to the sea, the loss of the Thwaites and Pine Island glacier could destabilize western Antarctica, according to climate scientists.

The ice loss in West Antarctica is driven by interactions with the Southern Ocean, particularly in the Amundsen Sea, according to the paper, which used data from a regional ocean model to understand future changes under different emissions scenarios in ocean heat.

Satellite images taken in February showed melting from below Thwaites, giving researchers a clearer picture on the parts of the glacier that are destabilizing the fastest.

Researchers announced in 2022 that Thwaites, among the fastest-changing glaciers in the region, was hanging on "by its fingernails."

While mitigation efforts may only prevent the "worst-case scenarios" in West Antarctica, other regions of the Antarctic are unlikely to lose substantial mass if current emissions targets are met, the researchers said.

In addition, the ice sheet will likely take centuries or millennia to fully respond to climate change, according to the paper.