Leidy Glacier in NW Greenland. Image: NASA Goddard
Scientists have discovered an ancient lakebed buried under a mile of ice in Greenland, providing a glimpse of what the remote region looked like in the past—and how it might look in a future shaped by human-driven climate change.The bygone lake once covered an area of about 2,700 square miles, which is about the size of Rhode Island and Delaware combined. Though the basin is now filled with ice and sediment, it contained some 140 cubic miles of liquid water hundreds of thousands—or perhaps even millions—of years ago, according to a study published on Tuesday in Earth and Planetary Science Letters.
“We suggest that the basin once hosted a lake at a time when it was not covered by ice, likely during a past time interval when the Greenland Ice Sheet was reduced in extent compared to the present day,” said Guy Paxman, a postdoctoral researcher at Columbia University's Lamont-Doherty Earth Observatory who led the study, in an email.“From the data we have at the moment there isn’t a way of directly constraining the age of the paleo-lake, but it may be possible to recover and date sedimentary material from the basin in the future,” he added.
Paxman and his colleagues named the ancient lakebed Camp Century Basin because it is located near the abandoned American military base of the same name. The researchers spotted the frozen lakebed through the ice with the help of airborne instruments, including radar, carried by NASA’s Operation IceBridge research fleet. Earlier this year, Paxman started combing through extensive aerial observations that were obtained by Operation IceBridge between 2010 and 2017. “When I focused in on northwest Greenland, the basin became quite conspicuous in the data,” he recalled. “It was then a case of drawing together the separate lines of evidence (as outlined in the study) that supported the interpretation that the basin formerly hosted a paleo-lake.” “It’s been exciting to make a finding like this in some of the least well understood terrain on the planet, and it can hopefully contribute to an improved understanding of past environmental conditions in Greenland,” he said.
The exact age of Camp Century Basin will be tricky to pin down just by looking at its imprint from the air. Its position deep under the ice sheet suggests that it first formed when this region of northwest Greenland was warmer and ice-free. These types of conditions may have cropped up many times over the past several million years as glaciers advanced and receded, so scientists would need a direct sample of the submerged basin to pinpoint the exact age of the lake that once existed there.Given that Camp Century Basin is located under more than a mile of ice, it would require a sophisticated drilling effort to extract such a sample. However, past expeditions have plumbed ice to depths of two miles, so scientists may be able to eventually access some of the geological goodies that have been hidden in this lakebed for eons. “Deep sub-ice drilling is becoming increasingly viable, and there are several active science projects aiming to recover deep ice and/or bedrock in both Antarctica and Greenland,” Paxman said. “For this basin, the first step could be the deployment of a local seismic survey to more clearly image the sedimentary material within the basin and assess its suitability for sub-ice drilling.” Of course, it would be fascinating to peer at a sedimentary time capsule of ancient Greenland, especially given that drilled samples might contain fossils of animals and plants that lived in and around the lake. But Paxman and his colleagues also emphasize the importance of the discovery for anticipating the environmental changes that come with the melting of these Arctic ice sheets.“If we are able one day to recover material from the basin, it could be vital for learning more about how the Greenland Ice Sheet behaved during past time periods that might represent important analogues for the future of our climate,” Paxman concluded.Update: This article has been updated with comments from lead author Guy Paxman.