Rapid Melting of West Antarctic Ice Shelves Is ‘Unavoidable,’ Study Finds

Even under a best-case climate scenario, global sea levels will likely rise because of this accelerated melting, scientists say

Chilly scene on the water next to Antarctica
Ice shelves are important because they help keep ice on land from flowing into the ocean as quickly. Getty Images

As ocean temperatures continue to rise because of human-caused climate change, rapid melting of West Antarctica’s ice shelves now appears “unavoidable,” according to new research published Monday in Nature Climate Change.

Even under the best-case scenario of cutting emissions from fossil fuels, the ocean will continue to warm, and the ice shelves will experience “widespread increases” in melting, per the study’s modeling.

“It appears that we may have lost control of the West Antarctic ice shelf melting over the 21st century,” study co-author Kaitlin A. Naughten, an ocean scientist with the British Antarctic Survey, said at a press conference, per the New York Times’ Raymond Zhong. “That very likely means some amount of sea-level rise that we cannot avoid.”

Ice shelves stick out into the ocean from the edges of glaciers. They play an important role in Antarctica, as their mass helps prevent the ice on land from flowing quickly into the ocean. But as the ocean warms, its water laps against the ice shelves from below and speeds up their melting. As the shelves get thinner, they allow more of the ice on land to reach the ocean, contributing to sea-level rise.

Scientists developed a mathematical model to predict what this melting might look like under different future climate scenarios. They found that the Amundsen Sea—the part of the Southern Ocean that touches West Antarctica—could warm at three times the historical rate, even if the world limits global warming to 1.5 degrees Celsius above pre-industrial conditions. That’s the target set by the Paris Agreement, which, for now, the world seems likely to surpass.

The study is based solely on one model, which the scientists acknowledged as a limitation, but its conclusion does broadly align with past research.

“It seems clear from these [new] results that future sea-level rise of some degree is now locked in,” writes Taimoor Sohail, a mathematician at the University of New South Wales Sydney and the Australian Center of Excellence in Antarctic Science, in a commentary that accompanies the new paper.

The scientists did not estimate the exact amount of sea-level rise that accelerated melting of the West Antarctic ice shelves might cause. However, they have “every reason to suspect” that seas will rise if their models are correct, said Naughten, as reported by ABC News’ Julia Jacobo.

If all the glaciers of West Antarctica were to melt, they would cause seas to rise by an average of more than 17 feet, per the study. Notably, this region is home to two fast-moving glaciers that have been shedding ice into the ocean for decades: the Thwaites and Pine Island glaciers. The Thwaites Glacier has been nicknamed the “Doomsday Glacier,” because it alone has the potential to cause global sea levels to rise by roughly two feet.

With inevitable sea-level rise on the horizon, coastal communities “will either have to build around or be abandoned,” said Naughten, per NBC News’ Evan Bush.

Increased melting on the West Antarctic Ice Sheet is now unavoidable | British Antarctic Survey

To have any chance of halting the melting, the world would not only need to cut greenhouse gas emissions moving forward, but also remove some existing pollution from the atmosphere, says Ted Scambos, a glaciologist at the University of Colorado Boulder who was not involved in the study, to CNN’s Rachel Ramirez.

“The thing that’s depressing is the committed nature of sea-level rise, particularly for the next century,” Scambos tells CNN. “People who are alive today are going to see a significant increase in the rate of sea-level rise in all the coastal cities around the world.”

Antarctic sea ice is also declining—and its annual maximum level reached a record low in September—but scientists don’t know for sure what’s responsible for that change. However, they suspect warming ocean temperatures have something to do with it.

Though the new findings are sobering, working to halt global warming can still have a positive impact on the icy continent, past research has shown. For example, curbing greenhouse gas emissions could save the often-overlooked East Antarctic ice sheet—which, at roughly ten times larger than West Antarctica, could cause roughly 170 feet of sea-level rise if it were to melt entirely.

Beyond East Antarctica, by cutting fossil fuel use, “we could still avoid damage to coral reefs. We could still avoid heat waves,” Naughten said, per the Washington Post’s Scott Dance and Chris Mooney.

Get the latest stories in your inbox every weekday.