New analysis published in journal Communication Earth and Environment, starting with data from 1979, when accurate temperature estimates from satellite sensors became available for the first time. Researchers also defined the Arctic Circle as the area north of the Arctic Circle above about 66 degrees latitude.
How the region is defined “is a very important conversation in understanding changes in the Arctic,” said Thomas Ballinger, a researcher at the University of Alaska Fairbanks. A larger Arctic contains more land, reducing the impact of ice-water feedbacks on average temperatures.
Dr. Ballinger, who was not involved in either study, is the author of the Annual Arctic Report Card produced for the National Oceanic and Atmospheric Administration. He said some of the Finnish findings were of particular interest, including those that showed very high rates of warming in the late 1980s and 1990s. was,” he said.
An earlier study, published last month in Geophysical Research Letters, looked at data since 1960 to define a larger Arctic region north of 65 degrees north latitude, containing more land. It turns out that the rate of warming has reached four times his global average, which started about 20 years ago. Also, unlike the Finnish study, there were two his decades from the mid-1980s to his mid-1990s and his 2000s, which found that warming in the region took a big leap.
“It doesn’t change continuously, it changes in steps,” says Manvendra K. Dubey, an atmospheric scientist at Los Alamos. Also, the data spans 10 years, suggesting links to natural climate variability and warming from increased human-induced greenhouse gas emissions.
Dr Rantanen said his group’s results also point to a role played by natural variability in warming rates, possibly long-term changes in oceanic or atmospheric circulation.