[ad_1]
the Greenland The ice cap reached a point of rapid retreat from which it could not recover even as global temperatures stopped rising instantly.
This arctic ice cap is the second largest ice cap in the world, after the one that covers Antarctic. It covers most of Greenland and melts into the seas via outlet glaciers, which have been rapidly losing ice for decades. Today, new research reveals that today’s glacial 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 it ever lost. the annual snow fills it.
Projecting this trend into the future, the ice cap is expected to lose 99 mass over 100 years, the researchers reported in the journal Aug. 13. Nature Communications Earth and environment.
“The retreat of the glaciers has shifted the dynamics of the entire ice sheet into a constant state of loss,” says Ian Howat, study co-author, Earth scientist at Ohio State University. said in a press release. “Even if the climate were to stay the same or even get a little colder, the ice cap would still lose mass.”
Related: 10 signs the Earth’s climate is derailed
Increase in melting
The Greenland ice cap has long been in jeopardy. In January 2019, researchers reported in the journal Proceedings of the National Academy of Sciences that the ice cap was lose ice four times faster than in 2003. Other researchers have discovered that the ice cap is sliding over its underlying bedrock faster than expected. This slide 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 imagery with data from aerial surveys from Operation IceBridge, providing a detailed timeline of ice thickness, ice flow, sea level rise. ice and the location of the ice cap calving front – the line where glaciers hit the sea and lose ice through calving icebergs. This method allowed researchers to examine both seasonal changes in ice discharge and longer-term trends.
They found an increase of about 60 gigatonnes of ice loss per year between 2007 and 2018 compared to the period between 1985 and 1999. In total, the ice sheet has lost 4,200 gigatons of ice since 1985.
There are regional differences, with some of the acceleration of ice retreat between 2001 and 2005 caused by glaciers in southeast Greenland moving from relatively shallow parts of the seabed to deeper sections, where l hot water can more easily flow under them and melt them.
A future without ice?
But whatever the region of Greenland, the retreat of a 1 kilometer glacier is systematically associated with a 4% to 5% increase in the rate of ice discharge from that glacier. Since these slicks are already receding, further loss of ice occurs, even in a hypothetical situation where temperatures stop rising.
“Glaciers have been sensitive to seasonal melting for as long as we can observe it, with peak ice discharge in the summer,” says lead study author Michalea King, researcher at Byrd Polar and Climate Research Ohio State University Center. , said in the statement. “But from 2000 on, you start to overlay that seasonal melting on a higher benchmark – so you’re going to have even more losses.”
With the ice sheet poised to lose more ice than it gains each year, it may seem like the end of the Greenland ice sheet. But this future is not yet written, Stegan Rahmstorf, physicist and climatologist at the University of Potsdam noted on Twitter. Eventually, he says, the retreating ice will push the ice cap away from the ocean. At this point, the warm ocean waters will stop melting the ice and the glaciers will stop calving. The Greenland ice cap will become a fully terrestrial entity. When this happens, a new dynamic sets in: it will be a race between the rate of melting of the ice surface and the annual snowfall that will decide when and when the ice sheet disappears.
“So the loss of ice in Greenland is a real concern – already today it contributes a lot to the rise in sea level”, wrote Rahmstorf. “And Greenland has a tipping point where the ice cap is doomed to total loss. But the new paper by King et al. Does not say anything about whether this has been crossed.
Originally posted on Live Science.
[ad_2]
Source link