Growing Threat to Sea Levels: 'Zombie Ice'

Melting Greenland ice sheet expected to lose 3% of its mass, no matter what
By Newser Editors and Wire Services
Posted Aug 29, 2022 11:12 AM CDT
Growing Threat to Sea Levels: 'Zombie Ice'
A boat navigates at night next to large icebergs in eastern Greenland on Aug. 15, 2019.   (AP Photo/Felipe Dana, File)

"Zombie ice" from the massive Greenland ice sheet will eventually raise the global sea level by at least 10 inches on its own, according to a study released Monday. Zombie (aka doomed) ice is ice that's still attached to thicker areas of ice but is no longer getting fed by those larger glaciers, explains the AP. That's because the parent glaciers are getting less replenishing snow. Meanwhile, the doomed ice is melting from climate change, says study co-author William Colgan, a glaciologist at the Geological Survey of Denmark and Greenland. "It's dead ice—it's just going to melt and disappear from the ice sheet," Colgan notes. "This ice has been consigned to the ocean, regardless of what climate [emissions] scenario we take now."

The unavoidable 10 inches cited in the study is more than twice as much sea level rise as scientists had previously expected from the melting of Greenland's ice sheet. The study in the journal Nature Climate Change said it could reach as much as 30 inches. By contrast, last year's Intergovernmental Panel on Climate Change report projected a range of 2 inches to 5 inches for likely sea level rise from Greenland ice melt by the year 2100. "Every study has bigger numbers than the last," Colgan tells the Washington Post. "It's always faster than forecast."

What scientists did for the study was look at the ice in balance. In perfect equilibrium, snowfall in the mountains in Greenland flows down and recharges and thickens the sides of glaciers, balancing out what's melting on the edges. But in the last few decades there's been less replenishment and more melting, creating imbalance. Study authors looked at the ratio of what's being added to what's being lost and calculated that 3.3% of Greenland's total ice volume will melt no matter what happens with the world cutting carbon pollution, Colgan says. "I think 'starving' would be a good phrase" for what's happening to the ice, he notes.

(More Greenland stories.)

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