The rapid warming of the Arctic, a definitive sign of climate change, is occurring even faster than previously described. A new report by the Finnish Meteorological Institute concludes that the Arctic has warmed at about four times the global average rate over the last 43 years. Specifically, Arctic Circle — the area located above 66.5 degrees latitude — has warmed by more than 5 degrees Fahrenheit since 1979.

The Scientific American also reports that a separate group of scientists presented research at the annual meeting of the American Geophysical Union last December with similar findings. And just in June, another study by a different research team also cited a four-times Arctic warming figure (Climatewire, July 11).

Scientists have known for years that the Arctic is warming faster than the rest of the planet, a phenomenon known as “Arctic amplification.” But until recently, both scientific papers and news reports have typically reported that temperatures there are rising at about two to three times the global average rate.

“Of course, everyone knows that … the Arctic warms faster than the rest of the globe,” said Alexey Karpechko, a scientist at the Finnish Meteorological Institute and a co-author of the new study. “But I think the number — nearly four times that we found now — is simply quite impressive.”

Climate change has triggered a rapid loss in sea ice in the Arctic region, which in turn has amplified global warming. Bright white sea ice reflects solar energy back to space, but when it melts, the dark ocean absorbs that heat.

Thanks to David Rye for contributing to this post.