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Canada’s Ice Shelves Lose Quarter of their Cover

Posted by feww on September 3, 2008

Canada’s Ice Shelves Disappearing Much Faster than Previously Thought

The Markham Ice Shelf break-up animated using cloud-free MODIS images. The animation shows an area that is approximately 40 km wide. MODIS image from the Rapid Response Project at NASA/GSFC. Animation courtesy Derek Mueller, Trent University.

[Kudos to Derek Mueller for his plain, yet revealing animations. See  below also for Serson Ice Shelf break-up and Ward Hunt Ice Shelf break-up animations.]

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Markham Ice Shelf, a massive 50 square km ice shelf, almost the land size of Manhattan Island, in Canada’s northern Arctic broke away in August. The remaining shelves are shrinking at a “massive and disturbing” rate, as a result of of accelerating climate change, scientists reported.

The Markham Ice Shelf, one of just five remaining ice shelves in the Canadian Arctic, calved from Ellesmere Island in early August. Additionally, two other large chunks measuring a total of about 122 square km calved from Serson Ice Shelf, reducing its size by nearly two-thirds.


Chunk of ice are drifting away after calving from the Ward Hunt Ice Shelf off the north coast of Ellesmere Island in Canada’s far north. Photo: AP. Image may be subject to copyright.

“The changes … were massive and disturbing,” said Warwick Vincent, at Laval University in Quebec.

Vincent’s team have recorded peak temperatures of about  20 degrees Celsius (°C), some 12 degrees (250%) higher than the average of about 8°C. The team’s estimate that the shelves would lose 22 square km of ice this summer proved to be highly optimistic. The actual figure was closer to 220 square km—ten times higher than their estimate.

Before


A MODIS image of the Markham Ice Shelf (2006 extent outlined in red) on July 28, 2008 prior to calving. Note the open water in Markham Fiord south of the ice shelf. MODIS image from the Rapid Response Project at NASA/GSFC. Map courtesy Derek Mueller, Trent University.

After


A MODIS image of Markham Fiord on August 12, 2008 following the loss of the Markham Ice Shelf (2006 extent outlined in red). MODIS image from the Rapid Response Project at NASA/GSFC. Map courtesy Derek Mueller, Trent University.


The Serson Ice Shelf break-up animated using cloud-free MODIS images. The animation shows an area that is approximately 80 km wide. MODIS image from the Rapid Response Project at NASA/GSFC. Animation courtesy Derek Mueller, Trent University.

Scientists believe that global warming is increasing the temperatures in the Arctic far faster than the global average in the last 30 years.

“These substantial calving events underscore the rapidity of changes taking place in the Arctic,” said Derek Mueller, a specialist at Trent University in Ontario.


Markham Fiord in August 2008 after the Markham Ice Shelf broke away. Compare with the photograph above. Photo courtesy of Denis Sarrazin, Laval University.

“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,” he said.


The Ward Hunt Ice Shelf break-up animated using cloud-free MODIS images. The animation shows an area that is approximately 75 km wide. NB: The events displayed here were already widely reported at the end of July. MODIS image from the Rapid Response Project at NASA/GSFC. Animation courtesy Derek Mueller, Trent University.
According to Mueller a totl of about 215 square km of ice was lost from the shelves along Ellesmere Island this summer.

“Reduced sea ice conditions and unusually high air temperatures have facilitated the ice shelf losses,” said Luke Copland of the University of Ottawa.

“Extensive new cracks across remaining parts of the largest remaining ice shelf, the Ward Hunt, mean that it will continue to disintegrate in the coming years,” he said.


Calving of the Ward Hunt Ice Shelf into Disraeli Fiord during August 2008. Photo courtesy of Denis Sarrazin, ArcticNet/Centre d’Etudes Nordiques.

Ellesmere Island previously home to a single giant ice shelf measuring about 10,000 square km, now has four very small shelves covering only about 800 square km—less than a tenth of the original size!

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One Response to “Canada’s Ice Shelves Lose Quarter of their Cover”

  1. WcP Blog said

    Irreversible loss: 4,500-year-old 19-square-mile ice shelf breaks away in Canada, 10x loss expected this summer…

    (quote)

    TORONTO, Ontario (AP) — A chunk of ice shelf nearly the size of Manhattan has broken away from Ellesmere Island in Canada’s northern Arctic, another dramatic indication of how warmer temperatures are changing the polar frontier, scientists s…

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