Going, Going...?

Melting of the West Antarctic ice sheet, which projects off the White Continent like the bill of a cap, could raise global sea level by 20 feet and swamp many of the world's major cities. And guess what, everybody, it's melting. And so is the Greenland ice sheet, by the way, and at twice the rate previously thought. (Arctic sea ice is also melting, but like ice melting in a cocktail, it won't affect sea level as it's already floating.)

In Antarctica, the thinking had been that increased moisture in the atmosphere due to warming would lead to greater precipitation and that the continent would actually gain mass this century. It hasn't worked out that way so far. Satellite measurements indicate that Antarctica is now losing as much as 36 cubic miles of ice per year, as the ice shelf is sandwiched between warm water below and warm air above. In both Greenland and Antarctica, the breakup of ice around the edges of the shelf appears to have sped the flow of ice sheets to the ocean.

It should be pointed out that these findings are based on limited observations. One study looks at only three years of satellite data, from 2002-2005. As such, skeptics will assert that this is not a trend so much as a fluctuation. And for all our sakes, I hope they're right.