Researchers have mapped over 470 lakes under Antarctica's ice, including massive bodies of water like 143-mile-long Lake Vostok. But below Greenland’s ice sheet, the second largest in the world, scientists have only ever detected four lakes. Now, however, a new study has estimated that additional 56 bodies of water could lurk below the northern ice.
To find the subglacial lakes, Jade Bowling, a PhD candidate at Lancaster University, meticulously analyzed 341,000 miles worth of data collected by NASA’s IceBridge program, which uses ground penetrating radar aboard airplanes to create 3D maps of the ice in the Arctic and Antarctic each year. Jonathan Amos at the BBC reports that liquid water has a telltale backscatter pattern in the radar signals. Bowling found 54 candidate lakes hiding in that data and also found two more while looking at data from a new dataset of elevation maps called ArcticDEM. The research appears in the journal Nature Communications.
A previous study from 2013 had predicted that as many as 1,500 little lakes may hide under Greenland’s ice. Still, the discovery of several dozen lakes was unexpected. “Despite the number of lakes that were predicted to exist, we were quite surprised to find so many, given that so few had been previously discovered,” Andrew Sole, a physical geography researcher at the University of Sheffield, tells Hannah Osborne at Newsweek.
Cataloguing the lakes under the ice isn’t just an exercise in cartography. Knowing where they are and how they change over time can help researchers understand hydrology of the entire ice sheet.
“Researchers have a good understanding of Antarctic subglacial lakes, which can fill and drain and cause overlying ice to flow quicker. However, until now little was known about subglacial lake distribution and behavior beneath the Greenland Ice Sheet,” Bowling says in a press release. “This study has for the first time allowed us to start to build up a picture of where lakes form under the Greenland Ice Sheet. This is important for determining their influence on the wider subglacial hydrological system and ice-flow dynamics, and improving our understanding of the ice sheet’s basal thermal state.”
Unlike the lakes in Antarctica, which are relatively large, Greenland’s lakes range from a tenth of a mile long to about three and a half miles long. Most were found away from the stable interior of the ice sheet and closer to the edges. Unlike the lakes at the South Pole, some of which have been around for thousands of years, Greenland’s lakes appear to be younger and more active. The data shows evidence that at least two of the lakes drained and then refilled.
Sole tells Osborne that the lakes aren’t a major concern when it comes to climate change. But they are likely part of the mechanism that delivers melting ice into the oceans. As the surface ice melts, it refills these lakes, which then discharge water into the surrounding seas.
The team now plans to look at how active subglacial lakes influence the flow of ice in the upper layers of the ice sheet.
Study co-author Stephen J. Livingstone, also of the University of Sheffield, says they are also looking for lakes that might be worth drilling into. “These lakes could provide important targets for direct exploration to look for evidence of extreme life and to sample the sediments deposited in the lake that preserve a record of environmental change,” he says in the press release.