Iceberg in Jacobshavn Isfjord, Greenland. Photo by Evert Wesker.Greenland holds an important place on the frontier - both of the habitable world, and of global warming. Greenland is where sudden climate changes have been mapped, a phenomenon that was one of the first markers of global warming to be widely accepted. (Click here for a previous post.)
Greenland is back in the global warming news: the rate at which ice is leaving Greenland (through meltwater and ice shearing) is apparently accelerating.
The study was done by Eric Rignot (NASA's Jet Propulsion Laboratory) and and Pannir Kanagaratnam (Univ. of Kansas Center for Remote Sensing of Ice Sheets.)
Ten years ago Greenland was losing ice at a rate of 22 cubic miles/year. It has now increased to 53 cubic miles/year. The size of this number is staggering. (22 cubic miles/year was already incomprehensible.) 53 cubic miles has a weight of approximately 2.4 trillion tons. To put this number in perspective, an asteroid that is totally iron would be over a mile in diameter to have the same weight!
Glaciers at the edge of Greenland have picked up the pace to move this amount of ice, and some are moving up to 8 miles/year.
While some dispute the magnitude of the data, very few doubt that Greenland is losing ice.
The main culprit is most likely ocean warming leading to faster glacier movement. Because the increased rate of ice loss was not expected, it is clear that climate models must again be modified to account for this. This is not particularly easy given that the more ice lost, the higher the ocean level rises, but also there is a potential for lower water temperatures near the edge of Greenland. The lower temperatures may then slow down the ice loss.
The call for better modeling is urgent, according to one of the researchers (Rignot):
"The Greenland ice sheet's contribution to sea level is an issue of considerable societal and scientific importance... These findings call into question predictions of the future of Greenland in a warmer climate from computer models that do not include variations in glacier flow as a component of change. Actual changes will likely be much larger than predicted by these models."
Having had a chance many years ago to travel to Thule , Greenland, I am saddened by the thought that this great oasis of ice and tundra - the most austere and beautiful place that I have ever seen - is the biggest loser in our civilization's increasing negative effect on the planet.