With Speed and Violence Fred Pearce - Global Commons Institute

of that volume is water flowing out to sea from beneath the glacier, and half
is calving glaciers.
Other Greenland glaciers are getting up speed, too. The Kangerdlugssuaq
glacier, in eastern Greenland, which drains 4 percent of the ice sheet, was
flowing into the sea three times faster in the summer of 2005 than when last
measured in 1988. At an inch a minute, its movement was visible to the
naked eye. Meanwhile, its snout has retreated by three miles in four years.
This familiar pattern of faster flow, thinning ice, and rapid retreat of the ice
front has also shown at the nearby Helheim glacier, where Ian Howat, of the
University of California in Santa Cruz, concludes that "thinning has reached
a critical point and begun drastically changing the glacier's dynamics."
Most of these great streams of ice are exiting into the ocean beneath the
waterline, in submarine valleys, via giant shelves of floating ice that buttress
them. But as the oceans warm, these ice shelves are themselves thinning. It
is, says Hansen, a recipe for rapid acceleration of ice loss across Greenland.
The picture, then, is of great flows of ice draining out of Greenland,
lubricated by growing volumes of meltwater draining from the surface to the
base of the ice sheet and uncorked by melting ice shelves at the coast. All this
is new and frightening. "The whole Greenland hydrological system has
become more vigorous, more hyperactive," says Box. "It is a very nonlinear
response to global warming, with exponential increases in the loss of ice. I've
seen it with my own eyes. Even five years ago we didn't know about this."
Alley agrees: "Greenland is a different animal from what we thought it was
just a few years ago. We are still thinking it might take centuries to go, but if