Greenland’s rapidly melting ice sheet will eventually raise global sea levels by at least 27 centimetres — more than twice as much as previously forecast — according to a study published Monday.
That’s because of something that could be called zombie ice. That’s doomed ice that, while still attached to thicker areas of ice, is no longer getting replenished by parent glaciers now receiving less snow. Without replenishment, the doomed ice is melting from climate change and will inevitably raise seas, said 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 said in an interview. “This ice has been consigned to the ocean, regardless of what climate [emissions] scenario we take now.”
Study lead author Jason Box, a glaciologist at the Greenland survey, said it is “more like one foot in the grave.”
The unavoidable 27-centimetre increase predicted 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, published in the journal Nature Climate Change, said it could reach as much as 78 centimetres. By contrast, last year’s Intergovernmental Panel on Climate Change report projected a range of six to 13 centimetres for likely sea level rise from Greenland ice melt by the year 2100.