Two recent scientific studies had warned that the rate of melting of the ice may be changing the morphology of the frozen layer that covers this huge island in the North Atlantic, and the latest events seem to prove them right.
Researchers working on the most accurate map of the Greenland ice sheet have discovered that two lakes formed by meltwater underneath that sheet have dramatically disappeared . The surprise has been taken separately by two scientific teams who publish their results in the journals The Cryosphere and Nature .
One of the lakes has emptied to form a gigantic crater more than a kilometer and a half wide and 70 meters deep, according to the team of Ian Howat, professor of Earth Sciences at Ohio University, about 50 kilometers away. towards the interior of the southwest coast of Greenland. There, satellite images indicated there was a subglacial lake, but recent photos suggest that it likely emptied through a drainage tunnel. In the resulting crater, the researchers estimate that 25 million cubic meters of water could be stored.
The funny thing is that it disappeared in a few months, an unusual speed by geological standards. Howat and his team flew over the site in April 2014, after they noticed that the existence of the crater, situated in the middle of a flat expanse of ice, was not an error in capturing the high-resolution surface data they had been collecting. .
The second subglacial lake filled and emptied twice in the last two years. It was discovered by the team led by Cornell University’s Michael Willis, along with Ohio University researcher Michael Bevis, in March 2013. They were collecting GPS data to calculate the weight of the Greenland ice sheet when they discovered the lake by chance.
Based on satellite and NASA data, these experts estimate that the lake has been filled and emptied twice since 2012 – a cause for concern, as the water carries heat to the base of the ice sheet , which makes it the ice is more unstable and causes that there are more and more “pipes” through which the lakes drain.
Other studies suggest that the drainage system has recently extended some 50 kilometers into the frozen shelf , which is right where the first of the discovered lakes is. It is as if the meltwater has started to overflow the natural plumbing system under the icy layer causing blowouts that end up draining lakes. Although subglacial lakes have long been known to exist, scientists have never witnessed a drainage process. These two sudden findings indicate, for Professor Bevis, that the loss of ice in Greenland has reached dramatic levels.
