WASHINGTON -- The rapid melting in the Arctic eased up this year. But the government says global warming is still dramatically altering the top of the world, reducing the number of reindeer and shrinking snow and ice, while increasing certain fish and extending the growing season.
The National Oceanic and Atmospheric Administration issued its report card for the Arctic on Thursday, portraying 2013 as moderate compared with the roasting 2012.
Overall Arctic temperatures didn't soar quite as high, and Greenland ice sheets and summer sea ice didn't melt as much.
"The Arctic caught a break, if you will, in 2013, but one year doesn't change the long-term trend toward a warmer Arctic," said report card editor Martin Jeffries, a University of Alaska geophysicist who is the science adviser to the U.S. Arctic Research Commission.
"The Arctic has shifted to a new normal," Jeffries said at the American Geophysical Union scientific conference in San Francisco, where the 136-page report card was released.
While 2013 looks a tad cool compared with the last six years, it is unusually warm compared with the 20th century.
Central Alaska's summer was one of the warmest on record, coming months after its coldest April since 1924.
More ominous are long-term trends, NOAA's report card said.
Average Arctic temperatures have increased 3.6 degrees since the 1960s, rising twice as fast as the rest of the world. The growing season has lengthened by nearly a month since 1982.
While some fish and muskox are doing better, other animals associated with Arctic, like polar bears and walruses, are not. The report cited severe declines in the size of reindeer herds.
"Many of the herds at the overall level are at all-time lows," said study co-author Michael Svoboda of the Canadian Wildlife Service.
Jeffries and University of Virginia environmental scientist Howard Epstein, another study co-author, warned that changes in the Arctic reverberate around the globe.
White ice reflects solar energy, but because it is melting away, the oceans and the land are warming up more, Jeffries said.
He also cited a relatively new and evolving theory that is still dividing meteorologists. It says the loss of sea ice makes the jet stream meander and kink more, triggering more extreme weather in the Northern Hemisphere.
"The Arctic is not like Vegas," Epstein said. "What happens in the Arctic doesn't stay in the Arctic."
NOAA report card: http://www.arctic.noaa.gov/reportcard
Seth Borenstein can be followed on Twitter at: http://twitter.com/borenbears