The Arctic is under increasing stress with warming temperatures changing wildlife habitat and local climate conditions, researchers said Wednesday.
The amount of sea ice has fallen below previous record low levels, caribou herds are declining in manyareas and permafrost is melting, according to the annual update of the State of the Arctic report.
"The bottom line is we are seeing some rapid changes in the Arctic," said Richard Spinrad, assistant administrator for oceanic and atmospheric research at the U.S. National Oceanic and Atmospheric Administration.
Scientists have expected polar regions to feel the first impacts of global warming and the 2006 State of the Arctic report provided a benchmark for tracking changes. Wednesday's followup was the first update.
Winter and spring temperatures were all above average throughout the whole Arctic, said James Overland of NOAA's Pacific Marine Environmental Laboratory in Seattle.
"This is unusual and looks like the beginning of a signal from global warming," Overland said in a telephone briefing.
If you go back 100 years, it would be warm in one part of the Arctic and cold in another, Overland said. "We're not getting that now."
Sea ice cover this year has been 23 per cent smaller than the past record low set in 2005 and 39 per cent less than average, said Jacqueline Richter-Menge of the Cold Regions Research and Engineering Laboratory in Hanover, N.H.
She noted that the amount of older ice in the Arctic is significantly reduced, which makes it much more sensitive to change.
Warming affecting permafrost
Vladimir Romanovsky, of the Geophysical Institute at the University of Alaska at Fairbanks, said the warming is affecting the permafrost in Siberia, Alaska and other regions.
"This similarity of very different regions shows the changes are not local; they are on at least a hemispherical scale," Romanovsky said.
Mike Gill, of the Circumpolar Biodiversity Monitoring Program in Whitehorse, said the largest declines in caribou are in Canada and parts of Alaska.
The herds are sensitive to changes in their range and sometimes have problems migrating in changing conditions, meaning that calving occurs before they get to new feeding grounds, resulting in higher mortality.
The tundra itself is "shrubifying," he said and the increased shrub cover over many regions affects habitat and local climate, since it tends to absorb more solar radiation.
The global goose population has been on the increase, he added, resulting in overgrazing in some areas.