Antarctic Ice Shelf in Danger of Collapsing

Would raise worldwide sea level

At the rate it’s currently thinning, Antarctica's largest ice shelf will break off in about 80 years. But a large crack in the shelf threatens to hasten the process. (Hannes Grobe/Wikimedia Commons)

A study published Tuesday in the Cryosphere found that the largest ice shelf on the Antarctica Peninsula is at “imminent risk” of collapse. If the Larsen C shelf, which is twice the size of Hawaii, were to break off the continent, it would significantly raise the global sea level, according to Scientific American.

“If [Larsen C] collapses, it will cause several centimeters of sea-level rise, potentially within a few decades,” Paul Holland, lead author of the study and a scientist with the British Antarctic Survey, told Scientific American. “We therefore need to understand and predict this risk.”

The Larsen A and B ice shelves collapsed in 1995 and 2002, respectively, and if Larsen C were to break off, it would further exacerbate the problem of Antarctic disintegration. Ice shelves trap Antarctic glaciers on land, but the more that disappear, the faster the continental glaciers will slide into the ocean.

Larsen C is shrinking from both sides. Holland and his colleagues found that the ocean below it has warmed to 28 degrees, high enough to melt ice. Using radar waves to measure the ice’s thickness, the team found that Larsen C has lost 28 centimeters from the bottom every year for the past 15 years, according to Scientific American. The ice shelf’s top is losing four centimeters per year due to decreased snowfall and warmer temperatures.

Helen Fricker, a professor at the Scripps Institution of Oceanography and co-author of the study, told Outside that when a mass of ice like Larsen C breaks away from Antarctica, it changes the whole landscape. The post-glacial rebound—when the land rises without the weight of the ice pushing it down—may open up new areas of the continent. “When Larsen B collapsed, all of a sudden you could get a ship in there,” Fricker said.

At the rate it’s currently thinning, Larsen C will break off in about 80 years. But a large crack in the shelf threatens to hasten the process. “If the surface lowering continues at the rate we’ve seen, it’ll be about 2065,” Fricker said.

*Correction, May 14: The original story incorrectly stated that the Larsen C is the largest ice shelf on Antarctica.

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