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Arctic ice bigger than 2007, but thawing long-term

31.07.2008  |  123× přečteno      vytisknout článek 

OSLO (Reuters) - Arctic sea ice is unlikely to shrink below a 2007 record low this year in a reprieve from the worst predictions of climate change even though new evidence confirms a long-term thaw is under way, experts said.

By Alister Doyle, Environment Correspondent

The 2007 record raised worries of a melt that could leave the North Pole ice-free this year, threaten indigenous hunters and thaw ice vital for creatures such as polar bears. It would also help open the Arctic to shipping and oil and gas firms.

"Most likely there will not be a new record minimum ice year in the Arctic this September," said Ola M. Johannessen of the Nansen Environmental and Remote Sensing Center in west Norway.

Arctic sea ice area reaches an annual summer low in September but is about 1 million square kms (386,100 sq mile) bigger than at the same time in late July 2007 at about 6 million sq kms, an area almost as big as Australia.

It is still far smaller than the average of recent decades.

"It's looking rather unlikely that we will beat the record sea ice minimum of 2007," said Mark Serreze, a senior research fellow at the U.S. National Snow and Ice Data Center (NSIDC), adding there could still be surprises.

"The North Pole is likely safe for at least this year," he said. The NSIDC had suggested in May that it was "quite possible" that the pole could be ice-free this year.

"The basic reason that while last summer saw an ideal atmospheric pattern for melting sea ice -- essentially a "perfect storm" -- the pattern so far this summer has been characterized by somewhat cooler conditions," he said.

The 2007 low area of 4.13 million sq kms shattered a 2005 record and was among factors adding pressure on governments to slow a build-up of greenhouse gases from factories, power plants and cars. Governments have agreed to negotiate a new climate treaty by the end of 2009 to succeed the U.N.'s Kyoto Protocol.


Johannessen gave Reuters a hitherto unpublished study showing there was a 90 percent match between rising greenhouse gas emissions, mainly from use of fossil fuels, in recent decades and observations of a retreat of the ice.

"Ninety percent ... of the decreasing sea-ice extent is empirically 'accounted for' by the increasing carbon dioxide in the atmosphere," he wrote in the study, to be published next month in a journal by the Chinese Academy of Sciences.

If the match continues to hold true, the annual average ice extent would be several million km smaller by 2050 than predicted by the U.N. Climate Panel, which draws on the work of 2,500 scientists, it said.

Serreze said that he stood by a prediction that the Arctic Ocean could be ice-free in summer by 2030, decades before predictions by the Panel.

The Arctic has been warming about twice as fast as the rest of the globe in recent decades. Ice and snow reflect heat and any thaw uncovers darker ground or sea water that soak up the sun's warmth and further accelerate the melt.

Sheldon Drobot of the Colorado Center for Astrodymanics Research (CCAR), who predicted in April that there was a roughly 60 percent chance of a record 2008 Arctic melt, said he had cut chances to 40 percent and would probably revise them down again.

"Spring and summer temperatures in the Siberian coastal area are several degrees Celsius cooler in 2008 as compared to 2007," he said. "I am highly skeptical that we'll see an ice-free North Pole this year."

"Wind patterns that tend to push ice to the north have been mostly lacking this year," said James Maslanik, also at CCAR.

(Editing by Peter Millership)

source: REUTERS

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