A team of researchers from the University of Cambridge’s Scott Polar Research Institute has discovered two lakes about 800 m below the ice sheet near the town of Qaanaaq in northwestern Greenland.
This map shows the location of two subglacial lakes near the town of Qaanaaq in northwestern Greenland.
Subglacial lakes are likely to influence the flow of the ice sheet, impacting global sea level change. The discovery of the lakes in Greenland will help researchers to understand how the ice will respond to changing environmental conditions.
The Cambridge scientists used airborne radar measurements to reveal the lakes underneath the ice sheet.
The two lakes are roughly 8-10 km2, and at one point may have been up to 3 times larger than their current size.
They are found in the northwest sector of the Greenland Ice Sheet, about 40 km from the ice margin, and below 757 and 809 m of ice, respectively.
“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,” said Dr Steven Palmer, the lead author of the study published online in the journal Geophysical Research Letters.
The lakes are unusual compared with those detected beneath Antarctic ice sheets, suggesting that they formed in a different manner.
This radar map shows subglacial bed elevations near the town of Qaanaaq; lines show contours of the newly discovered subglacial lakes; dashed lines show possible previous larger contours. Image credit: S. J. Palmer et al.
The scientists propose 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. 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.
While nearly 400 lakes have been detected beneath the Antarctic ice sheets, the two newly discovered lakes are the first to be identified in Greenland.
Bibliographic information: Palmer SJ et al. 2013. Greenland subglacial lakes detected by radar. Geophysical Research Letters, published online; doi: 10.1002/2013GL058383
No comments:
Post a Comment