Arctic Sea Ice Decline Accelerates
By J.R. Pegg
WASHINGTON, DC, October 5, 2004 (ENS) - The floating mass of ice that covers the Arctic Ocean continues to melt rapidly and there is little doubt global warming is playing a role in the decline, scientists said on Monday.
The latest satellite information indicates the extent of Arctic sea ice last month was 13.4 percent below average - a reduction in area nearly twice the size of Texas.
Comparisons with earlier records indicate this was probably the least amount of sea ice that has covered the Arctic over the past 50 years.
The extent of Arctic sea ice in September is considered the most valuable indicator of the health of the ice cover, according to researchers with the University of Colorado at Boulder's (CU Boulder) National Snow and Ice Data Center.
"This is the third year in a row with extreme ice losses, pointing to an acceleration of the downward trend," said Mark Serreze, a researcher with the NSIDC and part of the team monitoring Arctic sea-ice conditions.
The decline in 2002 was about 15 percent, a record low, and was followed in 2003 with a decline of 12 percent below average.
The decline in Arctic sea ice during September traditionally marks the end of the summer melt season - it has averaged about eight percent over the past decade.
The CU-Boulder study shows that the September 2004 sea-ice loss was especially evident in extreme northern Alaska and eastern Siberia.
The researchers say that although natural variability is likely playing some part in the changes, the continuing loss of sea ice is a strong indicator that humans are altering the climate of the planet through the burning of fossils fuels.
"Climate models are in general agreement that one of the strongest signals of greenhouse warming will be a loss of Arctic sea ice," Serreze said. "Some indicate complete disappearance of the summer sea ice cover by 2070."
Global warming appears to be combining with the variable atmospheric circulation pattern known as the Arctic Oscillation, which may be contributing to the loss of the much thicker "multi-year" ice that has accumulated over many years.
"As winds and currents force this ice southward, more of it melts," said Julienne Stroeve, a CU-Boulder scientist with NSIDC involved in the research. "And while new ice is still forming in the winters, it is thinner, and therefore melts faster in the summer than older ice."
"We may soon reach a threshold beyond which the sea ice can no longer recover," Stroeve said.
This latest analysis of sea-ice satellite data comes amid increasing evidence that the Arctic - and Antarctica - and being already feeling the impacts of global warming.
A study released last month found glaciers in Antarctica are melting at an increasing rate in the wake of the collapse of a 1,200 square mile ice shelf in March 2002.
The recent events are a predicted consequence of climate change and underscore the potential for sea-level rise as a result of climate warming over the Earth's polar caps.
And native Arctic communities are growing increasingly worried about the changes to their environment from warming trends.
At a Senate hearing last month, Inuit Circumpolar Conference Chair Sheila Watt-Cloutier said there is little doubt climate change is already impacting the Arctic.
"The Earth is literally melting," said Watt-Cloutier, who represents the 155,000 Inuit in Greenland, Canada, Alaska and the Russian Federation.
Inuit hunters and elders have been observing changes to their environment for decades, Watt-Cloutier said, including unpredictable weather, melting of permafrost and glaciers, decreasing sea ice, as well as the presence of new species such as barn owls, robins and mosquitoes never seen before by the Inuit people.
The comments of the Inuit are also backed by the findings of the Arctic Climate Impact Assessment (ACIA), an international team of 300 scientists, experts, and indigenous residents of the Arctic region.
The ACIA is preparing a comprehensive analysis of the impacts and consequences of climate variability and changes across the region - their final report is slated for release next month.
It has found that in Alaska and western Canada, the average winter temperatures have increased by as much as 3 to 4 degrees Celsius over the past 60 years.
During the past 30 years, Arctic sea ice extent has decreased, on average, by about 10 percent, and this change has been 20 percent faster during the past two decades.
Continued melting of sea ice will lead to significant changes in the surface reflectivity, cloudiness, humidity, exchanges of heat and moisture, and ocean circulation, in particular along coastlines and near ice margins.
Two major conclusions of ACIA report are that marine species dependent on sea ice face an uncertain future and that global warming will disrupt - and potentially destroy - the Inuit culture.
Warmer climates could bring insects with diseases the Inuit have never know and the species they depend upon, such as the polar bear, are unlikely to survive if global warming continues unabated.
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