September 30, 2022

A zombie ice sheet from Greenland could raise sea levels by 10 inches

Greenland’s rapidly melting ice sheet could eventually raise global sea levels by at least 10.6 inches (27 centimeters) — twice as much as previously predicted — according to a study published Monday.

It is something that can be called zombie eyes. That lost ice, though still attached to thicker parts of the ice, is no longer replenished by parent glaciers that now receive less ice. If not replenished, ice destroyed by climate change will melt and inevitably raise seas, said William Colgan, a glaciologist at the Geological Survey of Denmark and Greenland.

“It’s dead ice. It’s melting off the ice sheet and disappearing,” Colgan said in an interview. “This ice is sent to the ocean, and now we’re taking on any climate (emissions) scenario.”

Jason Box, a glaciologist at the Greenland Survey, said it was “like a foot in the grave”.

The inevitable ten inches in the study is twice as much sea level rise as scientists had previously expected from the melting of Greenland’s ice sheet. The journal Nature Climate Change says it could be up to 30 inches (78 centimeters). In contrast, last year’s Intergovernmental Panel on Climate Change report predicted a range of 2 to 5 inches (6 to 13 centimeters) of ice melting from Greenland by 2100.

What the scientists did for the study was to look at the equilibrium of the ice. In perfect balance, snow flows down the mountains in Greenland and recharges and thickens the sides of the glaciers, balancing melting at the edges. But less filling and more melting in the past few decades has created an imbalance. The study authors calculated that 3.3% of Greenland’s total ice volume would melt regardless of what the world does to reduce carbon pollution, and what is lost is what is added, Colgan said.

“I think starving would be a good phrase for what’s happening to the ice,” Colgan said.

More than 120 trillion tons (110 trillion metric tons) of ice has already been lost to melting due to warming’s inability to fill the ice sheet’s edges, one of the study’s authors said. When that ice melts into water, if it accumulates only over the United States, it will be 37 feet (11 meters) deep.

The figures are global averages for sea level rise, but some places further away from Greenland will see more and places like the US East Coast will see less. While 10.6 inches isn’t much, it’s more than high tides and storms, and they’ll get worse, so sea-level rise will have “huge social, economic and environmental impacts,” said Elin Enderlin, a professor of geosciences. Boise State University, was not part of the study.

“It’s a very big loss and a detrimental effect on beaches around the world,” said NYU’s David Holland, who returned from Greenland but was not part of the study.

For Greenland, one of Earth’s two largest ice sheets, which is slowly shrinking, this is the first time scientists have calculated the minimum ice loss — and accompanying sea level rise. Due to climate change caused by burning of coal, oil and natural gas. The scientists used an accepted technique to calculate the minimum firm ice loss, which was applied to the mountain glaciers for the entire giant frozen island.

Pennsylvania State University glaciologist Richard Alley, who wasn’t part of the study but said it makes sense, said the definitive melting and sea-level rise is like an ice cube placed in a cup of hot tea in a warm room.

“You have taken a huge toll on the ice,” Ally said in an email. “Similarly, most of the world’s mountain glaciers and the edges of Greenland would lose mass if temperatures stabilized at modern levels as they were held in hot air like your ice cube was put into hot tea.”

Timing is an unknown here and a problem with the study, said two outdoor snow scientists, Lee Stearns of the University of Kansas and Sophie Nowicki of the University at Buffalo. The researchers in the study said they couldn’t estimate a definitive melt time, but in the last sentence they mention “within this century,” not backing it up, Stearns said.

The team doesn’t know how long it will take for all the lost ice to melt, but making an educated guess, it could be by the end of this century, or at least by 2150, Colgan replied.

Colgan said it was actually an ideal situation. 2012 (and a different amount in 2019 ) existed The Great Melting Year, When the balance between adding and subtracting snow was very unbalanced. If the Earth continues to continue for several more years like it did in 2012, Greenland melting could trigger 30 inches (78 centimeters) of sea level rise, he said. Those two years seem extreme now, but years that seem normal now would have been extreme 50 years ago, he said.

“That’s how climate change works,” Colgan said. “Today’s outliers become tomorrow’s averages.”


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