Strange Rumblings in Greenland

From the New York Times article, "The Warming of Greenland":

The abrupt acceleration of melting in Greenland has taken climate scientists by surprise. Tidewater glaciers, which discharge ice into the oceans as they break up in the process called calving, have doubled and tripled in speed all over Greenland. Ice shelves are breaking up, and summertime "glacial earthquakes" have been detected within the ice sheet.

It's important to remember that melting of the Arctic's polar ice cap does not affect sea level. It's already floating. Not so Greenland's ice sheets.

There is no consensus on how much Greenland's ice will melt in the near future, Alley said, and no computer model that can accurately predict the future of the ice sheet. Yet given the acceleration of tidewater-glacier melting, a sea-level rise of a foot or two in the coming decades is entirely possible, he said. That bodes ill for island nations and those who live near the coast.