The Big Thaw
Most glaciers in the Alps could be gone by the end of the century, Glacier National Parks namesake ice by 2030. The small glaciers sprinkled through the Andes and Himalaya have a few more decades at best. And the prognosis for the massive ice sheets covering Greenland and Antarctica? No one knows, if only because the turn for the worse has been so sudden. Eric Rignot, a scientist at NASAs Jet Propulsion Laboratory who has measured a doubling in ice loss from Greenland over the past decade, says: We see things today that five years ago would have seemed completely impossible, extravagant, exaggerated.
The fate of many mountain glaciers is already sealed. To keep skiing alive in Bolivia, Walter Laguna will need to find a bigger, higher ice field. And the millions of people in countries like Bolivia, Peru, and India who now depend on meltwater from mountain glaciers for irrigation, drinking, and hydropower could be left high and dry. Meanwhile, if global warming continues unabated, the coasts could drown. If vulnerable parts of the ice that blankets Greenland and Antarctica succumb, rising seas could flood hundreds of thousands of square milesmuch of Florida, Bangladesh, the Netherlandsand displace tens of millions of people.
Right now Greenland is no threat to beachfront property. Steven Nerem of the University of Colorado at Boulder, who monitors sea level by satellite, says the oceans have been rising an eighth of an inch (0.3 centimeter) a year. At that rate the sea would go up a foot (0.3 meters) by 2100, roughly what a United Nations panel on climate change predicted earlier this year. But thats nothing compared to what we expect if Greenland really starts to go, Nerem says.
The latest signs from Greenland have persuaded many ice researchers that sea level could rise three feet (one meter) by 2100. Rignot, who has measured the rush of glaciers to the sea, says even that figure may turn out to be an underestimate. Greenland, he notes, could ultimately add ten feet (three meters) to global sea level, and if this happens in the next hundred years instead of the next several hundred years, thats a very big deal.
http://ngm.nationalgeographic.com/2007/06/big-thaw/big-thaw-text