Scientists warn: Antarctica's “doomsday glacier” will retreat “further and faster”

The outlook for Doomsday Glacier has become even bleaker.

Scientists warn that the Antarctic ice sheet, officially called the Thwaites Glacier, will degrade “further and faster” and that sea level rise caused by the melting could affect hundreds of millions of people in coastal communities.

“Towards the end of this century or the next century, it is very likely that we will see a rapid increase in the amount of ice falling off Antarctica,” said Dr. Ted Scambos, a glaciologist at the University of Colorado. “The Thwaites are all but doomed.”

The results are the culmination of six years of research by the International Thwaites Glacier Collaboration, a group of over 100 scientists.

Doomsday Glacier is about the size of the state of Florida and is one of the largest glaciers in the world. Scientists predict that its collapse could cause sea levels to rise by 65 centimeters, or about 26 inches.

Sea level rise could be even higher if you take into account the ice that the Thwaites will absorb from the large surrounding glacial basins as they collapse. “Overall, sea level will rise by almost three metres,” Scambos said.

According to the researchers, the amount of water flowing into the sea from Thwaites and neighboring glaciers doubled between the 1990s and the 2010s.

About a third of the front of the Twaites is currently covered by a thick sheet of ice – an ice shelf – that floats in the sea and prevents ice from flowing out to sea. But Scambos said melting is accelerating and the ice sheet is “very close to breaking apart”.

“It will probably break apart into some large icebergs within the next two or three years,” he said. This will eventually expose the front of the glacier. This may not necessarily lead to a sudden acceleration of melting, but will change the way the ocean interacts with the front of the ice shelf, Scambos said.

Deep ridges that prevent ice from flowing into the sea are gradually disappearing. The ridges in the bedrock beneath the Antarctic ice sheet exert a “dragging force” on the ice, Scambos says, which slows its flow into the sea. If Thwaites collapses, it will lose contact with these protective ridges, causing even more ice to flow into the sea.

One of the most surprising discoveries of the International Thwaites Glacier Collaboration was how tidal activity around the glacier pumps warmer seawater into the ice sheet at high speed. This water, at a temperature several degrees above freezing, becomes trapped in parts of the glacier and is pushed further upstream.

“Every day it penetrates and gets compressed under the glacier. It melts all the freshwater ice it can reach and then gets ejected, and then the whole thing starts again,” Scambos said.

The new findings from the International Thwaites Glacier Collaboration add to a large body of research into how global glacier retreat may be contributing to sea level rise. In May, a study found that highly pressurized ocean water is seeping beneath the Doomsday Glacier, causing “intense ice melting.”

Co-author of the study Christine Dow called the Thwaites the “most unstable place in Antarctica” and said the rate at which the ice is melting could prove “devastating for coastal communities around the world”.

Researchers at the University of California, Irvine, predicted sea levels could rise by about 60 centimeters, or about 23.6 inches, roughly in line with predictions by scientists at the International Thwaites Glacier Collaboration.

Scientists also also warned of the possible consequences if the Greenland ice were to melt. According to Paul Bierman, a scientist at the University of Vermont, Greenland's melting ice mass is now the main reason for sea level rise. If the ice mass melts completely, scientists estimate that this could lead to a sea level rise of 6 to 7 meters.

Rising global temperatures associated with climate change have warmed oceans and created new wind patterns that make glaciers more vulnerable to melting.

“It's most likely related to the increase in greenhouse gases in the atmosphere, which is changing the wind patterns around Antarctica and therefore changing the ocean currents around Antarctica,” Scambos said. “That's the main culprit.”

Scientists believe that without intervention, the Thwaites could disappear completely by the 23rd century.