Geography of Greenland - Climate Change

Climate Change

The Greenland ice sheet is 3 kilometers (1.9 mi) thick and broad enough to blanket an area the size of Mexico. The ice is so massive that its weight presses the bedrock of Greenland below sea level and is so all-concealing that not until recently did scientists discover that Greenland might actually be three islands.

It is thought that before the Ice Age Greenland had mountainous edges, and a lowland (and probably very dry) center which drained to the sea by one big river flowing out westwards past where Disko Island is now.

There is concern about sea level rise caused by ice loss (melt and glaciers falling into the sea) on Greenland. Between 1997 and 2003 ice loss was 68–92 km3/a (16–22 cu mi/a), compared to about 60 km3/a (14 cu mi/a) for 1993/4-1998/9. Half of the increase was from higher summer melting, with the rest caused by velocities of some glaciers exceeding those needed to balance upstream snow accumulation (Krabill et al., L24402, GRL 2004). A complete loss of ice on Greenland would cause a sea level rise of as much as 6.40 meters (21.0 ft).

Researchers at NASA's Jet Propulsion Laboratory and the University of Kansas reported in February 2006 that the glaciers are melting twice as fast as they were five years ago. By 2005, Greenland was beginning to lose more ice volume than anyone expected – an annual loss of up to 52 cubic miles or 217 cubic kilometres per year, according to more recent satellite gravity measurements released by JPL. The increased ice loss may be partially offset by increased snow accumulation due to increased precipitation.

Between 1991 and 2006, monitoring of the weather at one location (Swiss Camp) found that the average winter temperature had risen almost 10 °F (5.6 °C).

Recently, Greenland's three largest outlet glaciers have started moving faster, satellite data show. These are the Jakobshavn Isbræ at Ilulissat on the western edge of Greenland, and the Kangerdlugssuaq and Helheim glaciers on the eastern edge of Greenland. The two latter accelerated greatly during the years 2004-2005, but returned to pre-2004 velocities in 2006. The accelerating ice flow has been accompanied by a dramatic increase in seismic activity. In March 2006, researchers at Harvard University and the Lamont-Doherty Earth Observatory at Columbia University reported that the glaciers now generate swarms of earthquakes up to magnitude 5.0.

The retreat of Greenland's ice is revealing islands that were thought to be part of the mainland. In September 2005 Dennis Schmitt discovered an island 400 miles (644 km) north of the Arctic Circle in eastern Greenland which he named Uunartoq Qeqertoq, Inuit for "warming island".