Subglacial lakes found in Greenland for first time: study

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WASHINGTON, Nov. 27 -- British researchers said Wednesday they have discovered two subglacial lakes 800 meters below the Greenland ice sheet.

While nearly 400 lakes have been detected beneath the Antarctic ice sheets, these are the first to be identified in Greenland, according to researchers from the University of Cambridge, who used airborne radar measurements to reveal the lakes.

They reported in the U.S. journal Geophysical Research Letters that the two lakes are each roughly 8 to 10 square kilometers, and at one point may have been up to three times larger than their current size.

Previously, the absence of lakes in Greenland had been explained by the fact that steeper ice surface in Greenland leads to any water below the ice being "squeezed out" to the margin, the researchers said.

"Our results show that subglacial lakes exist in Greenland, and that they form an important part of the ice sheet's plumbing system," Lead author Steven Palmer, formerly of the University of Cambridge and now at the University of Exeter, said in a statement.

"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," Palme said.

The lakes are unusual compared with those detected beneath Antarctic ice sheets, suggesting that they formed in a different manner.

The researchers proposed that, unlike in Antarctica where surface temperatures remain below freezing all year round, the newly discovered lakes are most likely fed by melting surface water draining through cracks in the ice.

A surface lake situated nearby may also replenish the subglacial lakes during warm summers, they said. This means that the lakes are part of an open system and are connected to the surface, which is different from Antarctic lakes that are most often isolated ecosystems.

The ice in Greenland is also thinner than that in Antarctica, resulting in colder temperatures at the base of the ice sheet, the researchers said. This means that any lakes that may have previously existed would have frozen relatively quickly, while the thicker Antarctic ice can act like an insulating blanket, preventing the freezing of water trapped underneath the surface.

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 researchers added.

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