National Geographic : 2010 Jun
2 1 0 GREENLAND Ice sheet Ice sheet Ice sheet Below sea level Ice sheet Bedrock Melt area Maximum thickness 2 miles Ice edge With a melt extent of at least 40 percent, 2007 set a record. Medium Estimate: 4.5°F rise in global temperature High Estimate: 9°F rise in global temperature 2-1 million years ago Separate glaciers merged to form a sheet of solid ice that covered most of the island most of the time. If melting continues at its current rate, the central plateau will slowly begin to rebound as the weight of the ice lifts from it. Scenarios for the year 2100 Climate change projections 2007 The solid ice sheet has depressed underlying rock by some 3,000 feet. Its weight also squeezes out a thin lip of ice to the sides. Covering some 80 percent of the island, the ice sheet measures more than 650,000 square miles. Shaped like a lens, the ice is solid at its thick center but riddled with decay around the edges. Ice-penetrating radar offers a detailed look at the land below. Every summer, as the ice margins melt and glaciers slide faster into the sea, Greenland loses more than twice the amount of ice in the European Alps. Annual Melt Area Almost three decades of sat- ellite data reveal an escalating trend in the extent of the ice- melt zone---the part of the ice sheet where melting occurs between April and October. The rest of the year, the entire ice sheet is frozen. Even during the warmer months much of the ice refreezes overnight.