Vive Le Canada

Arctic may lose all ice by 2040
Date: Saturday, March 17 2007
Topic:


Rapidly thinning Arctic sea ice may have reached a tipping point that threatens to disrupt global weather patterns, bringing intense winter storms and heavier rainfall to western Europe.


Satellite images taken since 1979 show that ocean ice cover in the region has declined steadily, with an estimated 38,000 square miles now being lost every year. Computer models predict sea ice could vanish from the Arctic ocean completely as early as 2040.


ARCTIC MELT ACCELERATION

......Sea temperatures in the Arctic have risen 3C in recent decades due to a buildup of greenhouse gases in the atmosphere, according to Mark Serreze, who led the study at the University of Colorado, Boulder. He fears continued thinning of the ice will lead to a sudden acceleration of melting that will leave the ocean ice-free.

...... ‘When the ice thins to a vulnerable state, the bottom will drop out and we may quickly move into a new, seasonally ice-free state of the Arctic. There is some evidence that we may have reached that tipping point.’

...... Shifting wind patterns in the 1980s and 1990s forced much of the thick sea ice out of the Arctic ocean into the North Atlantic where it drifted south and melted. It was replaced with a thinner coverage of sea ice that ebbs and flows, but is gradually vanishing, leaving more open water to absorb heat from the sun, driving a cycle of warmer waters and increased melting.


ANTARCTIC ICE

......A team of British scientists raise concerns over four of the largest glaciers in the Antarctic, warning they may pose a disproportionate threat to global sea level rises as they slide into the ocean.

...... Thinning of the Antarctic ice sheets is countered, and in some places, compensated for, by heavier snowfall that acts to rebuild the ice packs to around 2km thick.

...... They identified the four glaciers as retreating in unison, driving the thinning of the ice sheets and representing the greatest risk to sea levels.

...... The Pine Island and Thwaites glaciers on the western Antarctic ice sheet, and the Totten and Cook glaciers on the eastern Antarctic ice sheet are now sliding into the water between 20% and 100% faster than in recent decades.

......"Although the amounts of water aren't yet that large, the concern is that we simply don't know what's causing this acceleration of these glaciers. It may be that warm ocean water is getting underneath them and making them flow more easily," said Dr Wingham.

...... The four glaciers are similar, lying in deep-seated basins that flow directly into the ocean, said Dr Andrews. "These glaciers are vulnerable to small changes in ocean temperature, such as those that have occurred over the 20th century. A rise of less than 0.5C could have triggered the present imbalance," he said.


SOURCE:..... Arctic may lose all ice by 2040


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RECALL:

Ice melt doubts in new climate report
Many top U.S. scientists reject the rosier IPCC numbers for sea level rise, saying the calculations don't include the recent, and dramatic, melt-off of big ice sheets in two crucial locations.


Arctic may lose all ic... Ice melt doubts in new...



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