19-square-mile ice sheet breaks loose in Canada

The Artic Ocean's ice cover has suffered its second-largest retreat in three decades this summer, including a nearly Manhattan-sized ice shelf that broke completely from an island in Canada's polar frontier and went adrift, scientists said. The region's ice shelf over the summer has lost 212 square kilometers, reducing the Arctic Ocean ice cover to its second-biggest retreat since satellite measurements began 30 years ago, Martin Jeffries of the US National Science Foundation and University of Alaska Fairbanks, said in a statement Tuesday. "These changes are irreversible under the present climate and indicate that the environmental conditions that have kept these ice shelves in balance for thousands of years are no longer present," said Derek Mueller, an Arctic ice shelf specialist at Trent University in Ontario. Formed by accumulating snow and freezing meltwater, ice shelves are large platforms of thick, ancient sea ice that float on the ocean's surface but are connected to land.