Ninety-nine percent of the planet’s freshwater ice is locked up in the Antarctic and Greenland ice caps. Now, a growing number of studies are raising the possibility that as those ice sheets melt, sea levels could rise by six feet this century, and far higher in the next, flooding many of the world’s populated coastal areas. Christopher Michel/Flickr. West Antarctica’s glaciers and floating ice shelves are becoming increasingly unstable. Last month in Greenland, more than a tenth of the ice sheet’s surface was melting in the unseasonably warm spring sun, smashing 2010’s record for a thaw so early in the year. In the Antarctic, warm water licking at the base of the continent’s western ice sheet is, in effect, dissolving the cork that holds back the flow of glaciers into the sea; ice is now seeping like wine from a toppled bottle. The planet’s polar ice is melting fast, […]