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News :: Environment |
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Planet Getting Hot & Extreme Storms Coming Soon, Largest Arctic Ice Shelf Breaks In Two After 50,000 Years |
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by Michael
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24 Sep 2003
Modified: 06:57:52 PM |
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The largest ice shelf in the Arctic, a solid feature for at least 50,000 years, has broken in two and is melting fast, climate change is to blame, say American and Canadian scientists. |
The Ward Hunt ice shelf, on the north coast of Ellesmere Island in Canada, has split down the middle, and a freshwater lake held behind it has drained away, the researchers say.
Reporting in the journal Geophysical Research Letters, the scientists say the fracture, which had been developing since 2000, was further evidence of continuing and accelerating climate change in the north polar region.
Much evidence suggests that the sea ice covering the Arctic Ocean is rapidly thinning and retreating, with reports two years ago that at one stage the North Pole itself was actually seawater rather than ice.
The break-up of the ice shelf - floating ice attached to land - shows a relatively rapid temperature rise. The ice, which formed a cap at the end of the 20-mile long Disraeli fjord, was the largest remaining piece of an ice shelf that once ran the length of Ellesmere Island.
It began to break up 10 years ago and by 1998 about 90 per cent of it was gone, say the scientists, Warwick Vincent and Derek Mueller of Laval University in Quebec City, and Martin Jefferies of the University of Alaska at Fairbanks.
In April 2000, satellite images showed the beginnings of cracking from the eastern side of Ward Hunt Island into the fjord, and by 2001 it had split along its length, then widened in 2002 to 85 yards in some places.
It has spawned several ice islands, some large enough to endanger shipping and drilling platforms in the Beaufort Sea.
A layer of freshwater on the top of the fjord that was dammed by the shelf, and contained a unique ecosystem rare plankton and other life, has drained into the Arctic Ocean.
The Ward Hunt shelf was up to 100ft thick, far thicker than the sea ice on the Arctic Ocean's surface, which averages 10ft.
The researchers said its disintegration seemed to have been prompted by a manmade Global warming, by rising concentrations of greenhouse gases, it was one of many signs the Arctic is seeing rapid and enormous climatic changes.
"We believe it's the result of recent human activity," said Dr Vincent, a biologist in polar ecology. "But the most recent changes are substantial and correlate with this recent increase in warming seen from the 1960s to the present. A critical threshold has been passed we will see drastic change in our climate in the next few years."
"It is accepted that the global climate is rapidly warming, the effects are being felt first in the polar regions, and they will be amplified in the temperate regins of the planet," said Dr Jefferies, a geophysicist.
"This is part of that extreme change to come." Recent records show there has been a local increase of 1.4 degrees C every decade since 1967. Since then the average July temperature has been above freezing, at 1.3C.
Professor Julian Dowdeswell, director of Britain's Scott Polar Research Institute in Cambridge, said the break-up of Ward Hunt ice shelf caused by man-made climate change, he said recent changes in sea-ice thickness and extent also are manifestations of global warming, and the break-up of Ward Hunt are part of that pattern.
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