Role of Meltwater Lakes in Greenland Ice Loss
21.04.2008 - Other
Researchers from the Woods Hole Oceanographic Institution (WHOI) and the University of Washington (UW) have, for the first time, studied the entire draining process of a meltwater lake above the Greenland ice sheet. Conclusions brought forward by lead scientists confirm the Greenland ice sheet plumbing system; show the contribution of summertime melt to the speed up of ice loss; but reveal that summertime melt is not as critical as other causes of ice loss.
Until now, little was know about what happened to the thousands of lakes which form on top of Greenland's glaciers and which can disappear as rapidly as in a year. For years, scientists believed that an increased length and/or intensity of the melt season in Greenland were the main causes for increased ice discharge into the ocean.
Using Global Positionning System (GPS) equipment to measure ground movement locally over frequent intervals and crossing the data with that collected by RADARSAT, these first-of-a-kind observations come to the following conclusions:
- The slow-moving ice sheet creeps towards the ocean and discharges ice in the form of icebergs. Although the ice sheet experiences significant seasonal speed-ups, it contributes very little to ice loss;
- The landscape also discharges ice into the ocean through its fast-moving outlet glaciers (rivers of ice that channel through bedrock valleys and that move 10 times faster than the ice sheet). Although these outlet glaciers contribute far more to ice loss than the ice sheet, the analysis carried out today reveals that they are not affected so much by seasonal melt, rather by the removal of their shelves and grounded ice in their fjords.
