Zombie ice from the massive Greenland ice sheet will eventually raise global sea levels by at least 10 inches (27 centimeters) on its own, according to a study released Monday.
Zombie or doomed ice is ice that is still attached to thicker areas of ice, but is no longer fed by those larger glaciers. That’s because the main glaciers receive less replenishing snow. Meanwhile, doomed ice is melting because of climate change, said study co-author William Colgan, a glaciologist at the Geological Survey of Denmark and Greenland.
It’s dead ice. It will just 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.”
The study’s lead author, Jason Box, a glaciologist on the Greenland study, said it’s “more like a foot in the grave.”
The unavoidable ten inches in the study is more than twice the sea level rise that scientists previously expected from the melting of the Greenland ice sheet. The study in the journal Nature Climate Change said it could reach up to 30 inches (78 centimeters). By contrast, last year’s Intergovernmental Panel on Climate Change report projected a range of 2 to 5 inches (6 to 13 centimeters) for likely sea level rise due to Greenland ice melt by the year 2100.
What the scientists did for the study was observe the ice in equilibrium. In perfect balance, snowfall in the mountains of Greenland flows down and recharges and thickens the sides of glaciers, balancing what melts at the edges. But in recent decades there is less replenishment and more melting, creating imbalance. The study authors looked at the ratio of what is added to what is lost and calculated that 3.3% of Greenland’s total ice volume will melt no matter what happens to the global reduction in carbon pollution, he said. They hang up.
“I think starving to death would be a good phrase” for what’s happening to the ice, Colgan said.
One of the study’s authors said that more than 120 billion tons (110 billion metric tons) of ice is already doomed to melt due to the inability of the warming ice sheet to replenish its edges. When that ice melts into water, if it were concentrated just over the United States, it would be 37 feet (11 meters) deep.
This is the first time that scientists have calculated a minimum ice loss, and subsequent sea level rise, for Greenland, one of Earth’s two massive ice sheets. that gradually shrink due to climate change from burning coal, oil and natural gas. The scientists used an accepted technique to calculate the minimum committed ice loss, the one used in mountain glaciers for the entire frozen giant island.
Pennsylvania State University glaciologist Richard Alley, who was not part of the study but said it made sense, said committed melting and sea level rise is like an ice cube placed in a cup of hot tea on a warm room.
“He has made a massive ice loss,” Alley said in an email. “In the same way, most of the world’s mountain glaciers and the edges of Greenland would continue to lose mass if temperatures stabilized at modern levels because they were placed in warmer air just like an ice cube was put into in hotter tea.”
Although 10 inches doesn’t sound like much, it’s a global average. Some coastal areas will be hit harder, and high tides and storm surges could be even worse, so this large sea level rise “will have huge social, economic and environmental impacts,” said Ellyn Enderlin, a professor of geosciences at Boise. . State University.
Time is the unknown key here and a bit of a problem with the study, said two outside ice scientists, Leigh Stearns of the University of Kansas and Sophie Nowicki of the University at Buffalo. The study’s researchers said they couldn’t estimate the time of the meltdown, but they mention “within this century” in the last sentence without supporting it, Stearns said.
Colgan responded that the team doesn’t know how long it will take for all the doomed ice to melt, but taking a guess, it’s probably by the end of this century or at least 2150.
Colgan said that this is actually the best case scenario. The year 2012 (and in another grade 2019 ) what great Fusion Year, when the balance between adding and removing ice was more unbalanced. If Earth begins to experience more years like 2012, Greenland’s melting could cause sea level rise of 30 inches (78 centimeters), she said. Those two years seem extreme now, but the years that seem normal now would have been extreme 50 years ago, she said.
“This is how climate change works,” Colgan said. “Today’s outliers become tomorrow’s averages.”