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Scientists have discovered an ancient lake bed buried under more than a mile of ice that may hold secrets about Greenland’s past climate.
The lake formed in the northwest Greenland was free of ice, sometimes hundreds of thousands or even millions of years ago. Given the rapid melting of Greenland today, the lake could reveal something about the future of the Arctic as the ice caps shrink.
“This could be an important repository of information, in a landscape that is currently totally hidden and inaccessible,” said Guy Paxman, postdoctoral researcher at Columbia University’s Lamont-Doherty Earth Observatory, said in a press release. “We are working to try to understand how the Greenland ice sheet has behaved in the past. This is important if we are to understand how it will behave in the decades to come.
Related: Melting images: disappearing ice
Buried in ice
Paxman and his colleagues discovered the lake using data from instruments that use radar to penetrate below the ice surface to measure topography; most of the data came from NASA’s Operation IceBridge.
The lake basin lies 1.8 kilometers below the ice surface and spans 7,100 square kilometers (2,700 square miles), the size of Rhode Island and Delaware combined. At its deepest point, the lake would have extended about 800 feet (250 meters) below.
The researchers also mapped 18 stream beds that would have flowed into the lake from the north, as well as an outlet that would have drained the lake to the south. Today this ancient water system is nothing but sediment, and scientists don’t know when it last held water. According to Previous searchThe Greenland 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 for 30 million years.
Past and future
The depth of sediment in the lake suggests it is between hundreds of thousands and millions of years old, Paxman said. To be more specific than that, scientists would have to drill under the ice in the lake’s sediments to study them directly.
The lake may have formed when an ancient rift separated the Earth, creating a depression, the researchers said, or it may be a bowl carved out by a retreating glacier.
Drilling in the lake bed could also provide clues to the future. The lake bed may contain traces of certain chemicals or fossils that could reveal more about Greenland’s past climate. Scientists could then compare these past conditions with the changing conditions in the Arctic today.
There are currently no plans to drill in the lake bed, but such a feat would be possible. In 2003, researchers drilled 3,085 m below the ice surface in Greenland. A project that should be launched in 2021 called GreenDrill will aim to drill into bedrock at several sites in northern Greenland to determine when and for how long parts of the area were ice free in the past.
Paxman and colleagues reported their results online Oct. 28 online in the newspaper Earth and planetary science letters.
Originally posted on Live Science.
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