Alaska's glaciers, which cover an area five times larger than the Patagonia glaciers,
account for about 30 percent of total annual global sea-level rise from mountain glaciers.
NASA scientists have concluded that the cause of glacial retreat is climate change, as evidenced by increased air temperatures and decreased precipitation.
Still, those factors alone are not sufficient to explain the rapid thinning. The rest of the
story appears to lie primarily in the unique dynamic response of the region's glaciers
to climate change.
The Patagonia Icefields are dominated by 'calving' glaciers, that spawn icebergs into the ocean or lakes, and have different dynamics from glaciers that end on land and melt at their front ends.
Calving glaciers are more sensitive to climate change once pushed out of equilibrium, and make the Patagonia region the fastest area of glacial retreat on Earth.
The Northern Patagonia Icefield in Chile and the Southern Patagonia Icefield in Chile and Argentina, cover 13,000 and 4,200 sq. km (5,019 and 1,622 sq. miles), respectively. The region, spanning the Andes mountain range, is sparsely inhabited, with rough terrain and poor weather.
Precipitation in the region ranges from 2 to 11 meters (6.6 to 36 feet) of water equivalent per year, a snow equivalent of up to 30 meters (98.4 feet) a year.
The icefields discharge ice and meltwater to the ocean on the west side and to lakes on the east side, via rapidly flowing glaciers. The fronts of most of these glaciers have been retreating over the past half-century or more.