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Scientists have discovered an ancient lake bed buried under more than a mile of ice that could hide secrets from Greenland’s past climate.
The lake was formed in the northwest Greenland it was ice-free, sometimes hundreds of thousands or even millions of years ago. Given Greenland’s rapid melting today, the lake could reveal something about the future of the Arctic as the ice sheets shrink.
“This could be an important repository of information, in a landscape that is totally hidden and inaccessible right now,” Guy Paxman, postdoctoral researcher at Columbia University’s Lamont-Doherty Earth Observatory, he said in a statement. “We are working to try to understand how the Greenland ice sheet has behaved in the past. It is important if we are to understand how it will behave in the decades to come.”
Related: Melting images: ice disappearing from the Earth
Buried in ice
Paxman and his colleagues discovered the lake using data from instruments that use radar to penetrate beneath the ice surface to measure topography; much of the data came from NASA Operation IceBridge.
The lake basin sits 1.1 miles (1.8 kilometers) below the ice surface and spans over 2,700 square miles (7,100 square km), the size of Rhode Island and Delaware combined. At its deepest point, the lake would have extended to about 250 meters deep.
The researchers also mapped 18 streams that would flow into the lake from the north, as well as an outlet that would drain the lake to the south. Today, this ancient water system is nothing more than sediment, and scientists don’t know when it last held water. Second previous search, Greenland’s ice has advanced and retreated at various points over the past million years. According to the Lamont-Doherty Earth Observatory, there may also have been ice-free stretches in the past 30 million years.
Past and future
The depth of the sediments in the lake suggests it is hundreds of thousands to millions of years old, Paxman said. To be more specific, scientists would have to drill beneath the ice in the lake’s sediments to study them directly.
The lake could have formed when an ancient fault split the Earth, creating a depression, the researchers said, or it could have been a bowl carved out of a retreating glacier.
Drilling the lake bottom could also provide clues for the future. The bottom of the lake may contain traces of certain chemicals or fossils that may reveal more about Greenland’s past climate. Scientists could then compare these conditions of the past with the changing conditions in the Arctic today.
There are currently no plans to drill the lake bottom, but such a feat would be possible. In 2003, researchers drilled 3,085m below the ice surface in Greenland. A project that will be launched in 2021 called GreenDrill it will aim to drill the bedrock at several sites in northern Greenland to determine when and for how long parts of the region were ice-free in the past.
Paxman and his colleagues reported their findings online Oct. 28 online in the journal Science letters of the earth and planets.
Originally published in Live Science.
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