Over 50 lakes discovered beneath Greenland Ice Sheet

Scientists have discovered 56 previously uncharted subglacial lakes beneath the Greenland Ice Sheet bringing the total known number of lakes to 60.

Although these lakes are typically smaller than similar lakes in Antarctica, their discovery demonstrates that lakes beneath the Greenland Ice Sheet are much more common than previously thought.

For the study published in the journal Nature Communications, researchers analysed over 500,000 km of airborne radio echo sounding data, which provide images of the bed of the Greenland Ice Sheet.

The team identified 54 subglacial lakes, as well as a further two using ice-surface elevation changes.

"Researchers have a good understanding of Antarctic subglacial lakes, which can fill and drain and cause overlying ice to flow quicker," said Jade Bowling of Lancaster University in the UK.

However, until now little was known about subglacial lake distribution and behaviour beneath the Greenland Ice Sheet.

"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," said Bowling.

"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," Bowling said.

The newly discovered lakes range from 0.2-5.9 km in length and the majority were found beneath relatively slow moving ice away from the largely frozen bed of the ice sheet interior and seemed to be relatively stable.

However, in the future as the climate warms, surface meltwater will form lakes and streams at higher elevations on the ice sheet surface, and the drainage of this water to the bed could cause these subglacial lakes to drain and therefore become active.

Closer to the margin where water already regularly gets to the bed, the researchers saw some evidence for lake activity, with two new subglacial lakes observed to drain and then refill.

"The lakes we have identified tend to cluster in eastern Greenland where the bed is rough and can therefore readily trap and store meltwater and in northern Greenland, where we suggest the lakes indicate a patchwork of frozen and thawed bed conditions," said Stephen J Livingstone, from University of Sheffield in the UK.

"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," said Livingstone.