The bed of a huge open lake buried under Greenland ice

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Thanks to radar, researchers recently detected the bed of a huge and ancient lake buried under the Greenland ice cap. This is the first time that such a structure has been discovered in the region.

The Greenland Ice Sheet is a vast mass of ice (the second-largest reservoir after Antarctica ) covering about 1,710,000 square kilometers (79% of Greenland’s area) and reaching up to 3.2 kilometers in depth in places. Under this ice are hidden a multitude of clues allowing researchers to better understand the past environmental conditions of this region.

For a long time, it was impossible to be able to access all this information. Now, advances in radar technology allow researchers to get a first glimpse of what lies beneath these billions of tons of ice.

A gigantic structure under 1.8 km of ice

Recently, using gravity and magnetic data provided by NASA, scientists were able to identify the remains of an ancient lake beneath 1.8 km of ice that once spanned about 7,100 square kilometers. The structure, which sank nearly 250 meters deep in places, was fed by more than a dozen streams.

The period during which this lake was formed is still a mystery. Researchers believe it could be as old as thirty million years old or have emerged just a few hundred thousand years ago. Still, for probably climatic reasons, the lake gradually dried up leaving behind only a bed of sediment 1.2 kilometers deep, sealed by ice. This is the first time that this type of subglacial feature has been discovered.

The best way to learn more would be to drill

“If we could reach these sediments, they could tell us when the ice was present or not,” said Guy Paxman, of Columbia University and lead author of the report. Sediment samples could also give us signs of ancient life in the form of plant spores or other organic matter.

Of course, such an undertaking will not happen overnight, as the technical and budgetary challenges are so important. The last major ice core drilling in Greenland (Greenland Ice Sheet Project 2) took place in the 1990s and has not been repeated since.

Especially since another project – named GreenDrill – aimed at drilling through the ice to the underlying bedrock, is also already in the papers. This promises to shed light on the past of the ice cap. This way, researchers will be able to refine their predictions on how it might contribute to rising sea levels. As a reminder, the Greenland ice sheet contains enough water to raise this level by more than seven meters.

Finally, this is not the first time that researchers have discovered geographical formations under the ice. Last year, 54 possible subglacial lakes containing large expanses of trapped water were also identified in Greenland.

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