Major Arctic ice shelf cracks, shedding 20 sq kilometres

Two chunks of ice together measuring almost 20 square kilometers (seven square miles) have broken off an Arctic ice shelf, the biggest breakup of Arctic ice in three years, Canadian officials announced.

Two floating islands of ice -- measuring four to five square kilometers (1.9 square miles) and 14 square kilometers (5.4 square miles) -- formed after the chunks broke from the Ward Hunt Ice Shelf off Ellesmere Island in the Canadian Arctic Archipelago, officials said.

"The first broke off sometime around July 22 and the second in the night of July 23 to 24," Luc Desjardins, a senior iceberg forecaster for Environment Canada's Ice Service, told AFP Tuesday.

Scientists confirmed the phenomenon in a fly-over of the first mass of ice and by analyzing satellite data.

It was the largest breakup of an ice shelf in the Arctic since the Ayles Ice Shelf broke off the Ellesmere Island coast in 2005 and formed a floating island of ice roughly the size of New York city's Manhattan, or about 66 square kilometers (25 square miles).

The August 2005 event emitted energy detected by Canadian seismology equipment 250 kilometers (155 miles) away, but it was not until scientists analyzed satellite data that they realized what had happened.

Five vast ice shelves surround the north side of Ellesmere Island in Canada's Nunavut Territory. Ward Hunt is considered the largest, with a surface area of 443 square kilometers (171 square miles).

The ice shelves, vast plateaus of thick ice floating on ocean but attached to land, began to form more than 4,000 years ago, Canadian scientists believe.