Two days ago, an "ice island" four times larger than Manhattan broke away from a Greenland glacier and is heading for the Nares Strait, and could reach the Atlantic Ocean within two years.

The ice island calved from the Petermann Glacier, and at a size of 100 square miles it is the largest break from a glacier in the Arctic since 1962. A researcher from the University of Delaware, Andreas Muenchow, in a press release said:

In the early morning hours of August 5, 2010, an ice island four times the size of Manhattan was born in northern Greenland. [...] The freshwater stored in this ice island could keep the Delaware or Hudson rivers flowing for more than two years. It could also keep all U.S. public tap water flowing for 120 days."

The island's thickness is about half the height of the Empire State Building, and has reduced the size of the Petermann Glacier by about one quarter. Muenchow believes the calving was part of a natural cycle.

[via Wired; Images via Getty, University of Delaware]