During their sovereignty patrol across the northernmost parts of Canada over the last two weeks, they visited a new 18 kilometre-long network of cracks running from the southern edge of the Ward Hunt Ice Shelf to the Arctic Ocean. This accompanies a large central fracture that was first detected in 2002, and raises the concern that the remaining ice shelf will disintegrate within the next few years.

Evidence of these cracks first came from Radarsat satellite images in February. Confirmation came from Canadian Rangers, partnering with International Polar Year scientists during Operation NUNALIVUT 08, a Canadian Forces High Arctic sovereignty patrol. Rangers mapped the extent of the fissures and monitored melt rates for Quttinirpaaq National Park, which encompasses the ice shelf.

The patrol scientists also found that the nearby Petersen Ice Shelf lost over a third of its surface area in 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.

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

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

Derek Mueller holds Trent's Roberta Bondar Fellowship in Northern and Polar Studies.

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• Global Warming
• Climate
• Ice Ages
• Oceanography
• Snow and Avalanches
• Geography

• Ice shelf
• Antarctic ice sheet
• Larsen Ice Shelf
• Iceberg
• Ice sheet
• Greenland ice sheet