Toronto, April 16 (IANS) The largest ice-shelf in the northern hemisphere has fractured into three pieces, the first intimation of which has come from images clicked by the Radarsat satellite. A team of scientists patrolling the area inspected an 18-km long network of cracks running from the southern edge of the Ward Hunt Ice-Shelf to the Arctic Ocean.

A similar large fracture was detected in 2002, prompting concerns that the remaining ice-shelf too would disintegrate within a few years.

“These latest break-ups that we are seeing have come after decades of warming and are irreversible,” said Derek Mueller of Trent University.

The scientists also found that the nearby Petersen Ice Shelf lost over a third of its surface area over the past three years. This ice shelf calved following the break-up of landfast sea ice in the summer of 2005 and 2007, which had protected it from the open ocean.

Only five large ice shelves remain in Arctic Canada, covering less than a tenth of the area than they did a century ago.

“Canadian ice shelves have undergone substantial changes in the past six years, starting with the first break-up event on the Ward Hunt Ice Shelf, and the loss of the Ayles Ice Shelf,” said Luke Copland of University of Ottawa.