November 28, 2013
Two Subglacial Lakes Discovered Beneath Greenland Ice Sheet
redOrbit Staff & Wire Reports - Your Universe Online
Researchers have discovered a pair of subglacial lakes discovered over 800 meters beneath the Greenland Ice Sheet – the first ever to be discovered in the island nation, according to research appearing in the latest edition of the journal Geophysical Research Letters.
The two lakes are reportedly between eight and 10 square kilometers in surface area, but might have been up to three times larger than their current size at one point, the researchers said in a statement Wednesday. The study was conducted as the Scott Polar Research Institute (SPRI) at the University of Cambridge and used airborne radar measurements to reveal the lakes underneath the ice sheet.
According to the study authors, subglacial lakes such as these could influence the flow of the ice sheet, thereby impacting global sea level change. The discovery of these new bodies of water in Greenland could help scientists better understand how the ice will be affected by changing environmental conditions, they added.
“Our results show that subglacial lakes exist in Greenland, and that they form an important part of the ice sheet's plumbing system,” explained lead author and former SPRI researcher Dr. Steven Palmer, who now works at the University of Exeter. “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.”
The newly-discovered lakes are unusual compared to those detected beneath Antarctic ice sheets, leading researchers to believe that they were likely formed in a different way. Unlike in Antarctica, where surface temperatures are below freezing throughout the year, the new subglacial lakes are probably fed by melting surface water that drains through the cracks in the ice.
Furthermore, they could also be partially replenished during the warm summers thanks to a nearby surface lake, Dr. Palmer and his colleagues said. That would mean that the lakes were part of an open system and were connected to the surface, which would make them different than the frequently isolated Antarctic lakes.
“While nearly 400 lakes have been detected beneath the Antarctic ice sheets, these are the first to be identified in Greenland,” the university said. “The apparent absence of lakes in Greenland had previously been explained by the fact that steeper ice surface in Greenland leads to any water below the ice being 'squeezed out' to the margin.”
Greenland’s ice is also thinner than the ice found in Antarctica, which results in colder conditions at the base of the ice sheet. For this reason, any lakes that might have existed in the past would have frozen relatively rapidly. The thicker Antarctic ice could have an insulating effect, keeping the water trapped below the surface from freezing.
“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 university added. “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.”
Back in August, researchers from the University of Bristol’s School of Geographical Sciences discovered one of the largest canyons in the world beneath the Greenland ice sheet. The study authors explained that the canyon is at least 750km (460 miles) long and up to 800m (2,600 feet) deep in some places.