The rapid melting in the Arctic eased up this year. However, the US 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 US National Oceanic and Atmospheric Administration (NOAA) issued its report card for the Arctic on Thursday, portraying this year as moderate compared with the roasting last year.
Overall Arctic temperatures did not soar quite as high, and Greenland ice sheets and summer sea ice did not 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 US 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 this year looks a tad cool compared with the past six years, it is unusually warm compared with the 20th century, he said.
Central Alaska’s summer was one of the warmest on record, coming months after its coldest April since 1924, NOAA said. Fairbanks experienced a record 36 days of more than 80oF (26.7oC). And snow cover in May and June was near record-low levels in North America and broke a record for the least snow in Eurasia.
However, one of the biggest climate change indicators, summer sea ice, was not as bad as expected. Sea ice this year reached its sixth-lowest level in the three decades that the agency has been keeping track. That is up from the lowest ever last year.
Yet the seven lowest levels have all occurred in the past seven years.
This year’s figure “is simply natural variability,” said National Snow and Ice Data Center director Mark Serreze, who was not part of the NOAA report, but praised it. “There is nothing about the year 2013 that provides any evidence that the Arctic is starting a path toward recovery.”
“Looking back 20 years from now, the world will be warmer and we’ll have much less sea ice than today. We’ll see that 2013 was just a temporary respite,” he added.
More ominous are long-term trends, the report card said.
Average Arctic temperatures have risen 3.6oF since the 1960s, rising twice as fast as the rest of the world. The growing season has lengthened by nearly a month since 1982.
Fish species are moving north, permafrost is melting, and shrubs are greening in ways that were not seen before.
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,” study co-author Michael Svoboda of the Canadian Wildlife Service said.
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.