Melting Ice Caps - 'Inevitable'

I guess I won't have to buy that Prius, after all:

A critical meltdown of ice sheets and severe sea level rise could be inevitable because of global warming, the world's scientists are preparing to warn their governments. New studies of Greenland and Antarctica have forced a UN expert panel to conclude there is a 50% chance that widespread ice sheet loss "may no longer be avoided" because of greenhouse gases in the atmosphere.

Such melting would raise sea levels by four to six metres, the scientists say. It would cause "major changes in coastline and inundation of low-lying areas" and require "costly and challenging" efforts to move millions of people and infrastructure from vulnerable areas. The previous official line, issued in 2001, was that the chance of such an event was "not well known, but probably very low".