Over 50 Subglacial Lakes Discovered Beneath Greenland Ice Sheet

Scientists have discovered 56 subglacial lakes hidden beneath the Greenland Ice Sheet. These lakes were found to be up to 3.6 miles in length and most were found to be dotted under the slow moving ice away from the main interior of the ice sheet.

Their discovery shows that subglacial lakes—bodies of water that form under a mass of ice—are more common than previously thought. Understanding the landscape beneath the Greenland Ice Sheet is important as it will help scientists understand how it might respond to climate change—models suggest that if it were to disintegrate, it could raise sea levels by up to seven meters.

Researchers have long known subglacial lakes exist under the Greenland Ice Sheet. A study from 2013 suggested there could be as many as 1,500 locked away beneath the ice. Despite this, only a handful have ever been identified, so researchers from the U.K.'s University of Lancaster set about finding them.

The team, led by Jade Bowling, analyzed over 550,000 kilometers (341,000 miles) of sounding data that used radio echoes to provide a view of the land under the ice. This allowed them to identify 56 subglacial lakes and map their distribution. This brings the total number of subglacial lakes identified in Greenland to 60.

Study co-author Andrew Sole told Newsweek: "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."

Subglacial lakes form in a number of ways—they can be the result of geothermal heat, from the pressure from the ice above, from heat generated by the ice moving, and from water on the surface draining down. In the study, published in Nature Communications, the team suggest there are three main zones of formation—providing an insight into which lakes are stable and which are not.

Image showing surface melt on Greenland Ice Sheet. Winnie Chu, Stanford University

Sole said that while the subglacial lakes in Greenland are not necessarily a big concern in terms of climate change, they do potentially store large amounts of surface meltwater, so may play a role in how ice melt is delivered to the ocean.

He added there are probably many more lakes to be discovered. The team now plans to look at how a certain type of subglacial lakes—the hydrologically active ones—can affect the flow of the ice above.

"Understanding the Greenland Ice Sheet is important because changes in its volume contribute directly to variations in mean global sea level," Sole said. "Greenland also sits in a region that is sensitive to changes in atmospheric and oceanic conditions, so it can experience large variations in the rate of ice melt, snowfall and delivery of ice to the surrounding oceans.

"In addition, sufficiently large changes in the amount of ice and meltwater that is discharged from the ice sheet into the north Atlantic are thought to be able to impact ocean circulation and regional climatic conditions."

In a statement, Bowling said: "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."