Two Subglacial Lakes Discovered Below the Greenland Ice Sheet

A team of British researchers has identified two subglacial lakes beneath the Greenland Ice Sheet.

Researchers at the University of Cambridge have identified two subglacial lakes present 800 meters below the Greenland Ice Sheet. The newly discovered lakes measuring almost 8-10 km2 will help researchers in studying how ice responds to the rapid change in the climate and environment.

The study, conducted at the Scott Polar Research Institute (SPRI), University of Cambridge, suggests that in the past the two lakes would have been three times larger than their current size and they probably control the flow of ice sheet thereby impacting the changes in global sea levels. The lakes were spotted using airborne radar measurement.

"Our results show that subglacial lakes exist in Greenland, and that they form an important part of the ice sheet's plumbing system. Because the way in which water moves beneath ice sheets strongly affects ice flow speeds, improved understanding of these lakes will allow us to predict more accurately how the ice sheet will respond to anticipated future warming," explains the lead author Dr Steven Palmer, formerly of SPRI and now at the University of Exeter.

On comparing the newly discovered lakes with lakes beneath the Antarctic ice sheets, it is evident that these lakes are formed in a different manner. The surface temperature of the lakes beneath Antarctic ice sheet remain below freezing point throughout the year, whereas the lakes beneath the Greenland Ice Sheet are fed by the melting surface waters that seep through the cracks in the ice. A surface lake placed close may also fill the subglacial lakes during the warm summers.

These lakes are part of an opens surface system dissimilar to the Antarctic ones, which are part of an isolated ecosystem.

These are the first lakes to be identified in Greenland, whereas under the Antarctic Ice Sheets more than 400 lakes have been identified. Due to the steeper ice surface in Greenland fewer lakes are formed. That is because the steep surface forces out the water below the ice to the margins. Also the Greenland ice is thinner in comparison to the Antarctica, due to which the temperature at the base of the ice sheet is colder. This factor causes the previously existing lakes to freeze rapidly. On the other hand, the Antarctica ice is thicker and plays the role of an insulating blanket, which prevents the water present beneath the surface from getting frozen.

The study further explains that, "As many surface melt-water lakes form each summer around the Greenland ice sheet, the possibility exists that similar subglacial lakes may be found elsewhere in Greenland. The way in which water flows beneath the ice sheet strongly influences the speed of ice flow, so the existence of other lakes will have implications for the future of the ice sheet."

The study was published in the Geophysical Research Letters.