De Greenland Ice Sheet has reached a point of rapid retreat that it could not recover, even as global temperatures stopped rising immediately.
This Arctic ice sheet is the second largest ice sheet in the world, after those with blankets Antarctica. It occupies the majority of Greenland and melts into the sea via exhaust glaciers, which have lost ice for decades. Now, new research finds that today’s current ice loss is 14% greater than it was between 1985 and 1999. The ice sheet loses about 500 gigatons of ice each year, more than is supplemented by annual snowfall.
Projecting this trend forward, the ice sheet is set to lose mass 99 out of every 100 years, researchers reported Aug. 13 in the journal Nature Communication Earth and environment.
“Glacier retreat has thrown the dynamics of the entire ice sheet into a constant state of loss,” study co-author Ian Howat, an earth scientist at Ohio State University, said in a statement. “Even if the climate remained the same or even got a little colder, the ice sheet would still lose mass.”
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Increase melt
The Greenland ice sheet has long been in danger. In January 2019, researchers in the journal Proceedings of the National Academy of Sciences reported that it was ice sheet ice lose at four times the rate it was in 2003. Other researchers have found that it is ice sheet glide on its underlying base faster than expected. This glide can move ice from the cold interior of Greenland to the warmer edges, where it melts faster.
The new study combined three decades of satellite images with data from Operation IceBridge aircraft surveys, and provided a detailed timeline of ice thickness, ice flow, ice elevation and the location of the bald front of the ice sheet – the line where glaciers lose sea and ice. ice by calving icebergs. This method enabled the researchers to look at both seasonal changes in ice discharge and longer-term trends.
What they found was an increase of about 60 gigatons of ice loss per year between 2007 and 2018 compared to the period between 1985 and 1999. All told, the ice sheet has lost 4,200 gigatons of ice since 1985.
There are regional differences, with some of the accelerating ice extraction between 2001 and 2005 driven by glaciers in the southeastern part of Greenland moving from relatively shallow parts of the sea flower into deeper parts, where warm water is easier to reach. them can circulate and melt.
Ice-free future?
But regardless of the region of Greenland, the retreat of a glacier 0.6 miles (1 kilometer) is consistently associated with an increase of 4% to 5% in the rate of ice discharge from that glacier. Because these leaks are already receding, further ice loss is embedded, even in a hypothetical situation in which temperatures stop rising.
“Glaciers have been susceptible to seasonal meltdown for as long as we could observe it, with spikes in ice discharge during the summer,” study lead author Michalea King, a researcher at Byrd Polar and Ohio State University’s Climate Research Center, said in the statement. “But in early 2000, you start to superimpose this season’s meltdown on a higher baseline – so you’ll get even more losses.”
With the ice sheet set to lose more ice than it wins each year, it may seem like the end of the Greenland ice sheet. But that future has yet to be written, physicist Potsdam University and climate scientist Stegan Rahmstorf noted on Twitter. Eventually, he said, the ice mining will pull the ice sheet off the ocean. At that point, warm ocean water will stop melting the ice, and the glaciers will stop calving. The Greenland ice sheet will become a complete entity on land. If that happens, a new dynamic will set in: It will be a race between the rate of surface melting of the ice and the annual snowfall that decides when and whether the ice sheet disappears.
“Thus, Groningen ice loss is a real concern – today it contributes a lot to sea level rise,” Rahmstorf wrote. “And Greenland does have a tipping point where the ice sheet is doomed to total loss. But King et al’s new paper says nothing about whether this has been overturned.”
Originally published on Live Science.
