Featured Science Paper
Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets
The most comprehensive picture of the rapidly thinning glaciers along the coastline of both the Antarctic and Greenland ice sheets has been created using satellite lasers. The findings are an important step forward in the quest to make more accurate predictions for future sea-level rise. The analysis of millions of NASA satellite measurements from both of these vast ice sheets shows that the most profound ice loss is a result of glaciers speeding up where they flow into the sea.
The authors conclude that this ‘dynamic thinning’ of glaciers now reaches all latitudes in Greenland, has intensified on key Antarctic coastlines, is penetrating far into the ice sheets’ interior and is spreading as ice shelves thin by ocean-driven melt. Ice shelf collapse has triggered particularly strong thinning that has endured for decades.
The paper also compares the rates of change in elevation of both fast-flowing and slow-flowing ice. In Greenland, for example, 111 fast-moving glaciers were studied and 81 found to be thinning at rates twice that of slow-flowing ice at the same altitude. They found that ice loss from many glaciers in both Antarctica and Greenland is greater than the rate of snowfall further inland.
In Antarctica some of the fastest thinning glaciers are in West Antarctica (Amundsen Sea Embayment) where Pine Island Glacier and neighbouring Smith and Thwaites Glacier are thinning by up to nine metres per year.
Hamish D. Pritchard, Robert J. Arthern, David G. Vaughan & Laura A. Edwards
Nature, 23 September 2009, doi:10.1038/nature08471