A large mass of ice broke off of Greenland's Petermann glacier on August 5th, 2010; the largest ice island to calve off Greenland since 1962. The ice island is immense; 4-times the size of Manhattan or over 100 square miles of surface area. The ice island is likely to break down to smaller ice bergs which will reach the Atlantic ocean within two years.
The ice island and Petermann glacier are located far north in the Arctic circle; 620 miles south of the North Pole. The newly form ice island was discovered by Trudy Wohlleben of the Canadian Ice Service via data from NASA's MODIS-Aqua satellite. The data was analyzed by Andreas Muenchow, an associate professor of physical ocean science and engineering at the University of Delaware.
The 100-square miles of the ice island has a thickness half the height of the Empire State building; over 600 feet thick. Muenchow says, "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 ice island will likely drift down the Nares Strait where it will likely become landlocked or broken into smaller ice bergs before eventually reaching the Atlantic Ocean. Previously in 1962, a 230 square mile ice island broke off the Ward Hunt Ice Shelf.