July 31, 2008
Arctic Ice May Undergo Long-Term Thawing
Although new evidence suggests that a long-term thawing of Arctic sea ice is currently under way, scientists withdrew previous prediction that the ice would shrink below a 2007 record low this year.
Previous reports highlighted a fear that the drastic melt witnessed in 2007 could lead to a total melt of ice on the North Pole."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.
In September, Arctic sea ice will hit an annual low, but will still be over 1 million square kms bigger than at the same time in late July 2007 at about 6 million sq kms, an area almost as big as Australia.
"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 of 4.13 million sq kms replaced the record set in 2005 and was a key piece of evidence scientists used to push new government action against 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.
"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.
Still, Serreze said that he stands by a prediction that the Arctic Ocean could be ice-free in summer by 2030, decades before predictions by the Panel.
Sheldon Drobot of the Colorado Center for Astrodynamics 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.
On the Net:
- Nansen Environmental and Remote Sensing Center
- U.S. National Snow and Ice Data Center
- Chinese Academy of Sciences
- Colorado Center for Astrodynamics Research