New analyzes find that the Arctic is warming 4 times faster than the rest of the planet

Researchers in Finland said Thursday that rapid warming in the Arctic, an ultimate sign of climate change, is happening faster than previously described.

Over the past four decades, the region has been warming four times faster than the global average, not the commonly reported rate two to three times. Some parts of the region, notably the Barents Sea in northern Norway and Russia, are warming seven times faster, they said.

The result is faster melting of the Greenland ice sheet, which leads to a rise in sea levels. But it also affects atmospheric circulation in North America and elsewhere, with effects on weather such as heavy rain And the heat wavesalthough some effects are debated among scholars.

While scientists have long known that average temperatures in the Arctic are increasing faster than the rest of the planet, the rate has been a source of confusion. Studies and news have estimated that it is two to three times faster than the global average.

Mika Rantanen, a researcher at the Finnish Meteorological Institute in Helsinki, said he and his colleagues decided to look into the problem in the summer of 2020, when it can be severe. Heat waves in the Siberian Arctic To be noticed.

“We are frustrated by the fact that there is a saying that the Arctic is warming twice as fast as the Earth is warming,” Dr. Rantanen said. “But when you look at the data, you can easily see that it’s close to four.”

The new results are supported by those of Another recent studyled by scientists at Los Alamos National Laboratory, who found similar rates of warming, despite their different time periods.

The Arctic has always been an important indicator of climate change, and limiting warming there by reducing greenhouse gas emissions will require international cooperation to avoid the most catastrophic impacts. Reducing emissions from the United States, which is historically the largest emitter and second only to China, is the focus of Biden’s climate management package that is expected to win congressional approval soon.

The Arctic is warming more quickly in large part due to a feedback loop in which warming is melting the sea ice in the region, exposing more Arctic Ocean to sunlight and causing more warming, which in turn leads to more melting and warming. The result of this and other oceanic and atmospheric processes is called arctic amplification.

How the rate of warming in the Arctic is described compared to the global average is partly related to the time period being analyzed and how the region is defined.

The new analysis published in the journal Earth and Environment Communications, begins with data from 1979, when accurate estimates of temperatures from satellite sensors first became available. The researchers also defined the Arctic as the region north of the Arctic Circle, above 66 degrees of latitude.

How the region is defined “is a very important conversation for understanding change in the Arctic,” said Thomas Ballinger, a researcher at the University of Alaska Fairbanks. A larger Arctic would encompass a larger area of ​​land, reducing the impact of ocean glacial reactions on average temperatures.

Dr. Ballinger, who was not involved in either study, is the author of the annual Arctic Report Card prepared for the National Oceanic and Atmospheric Administration. He said some of the findings from the Finnish study were particularly interesting, including those that showed very high rates of warming in the late 1980s and 1990s. “That was really when the amplification rates in the Arctic were the strongest,” he said.

The previous study, published last month in Geophysical Research Letters, looked at data from 1960 onwards and identified a larger polar region north of 65 degrees latitude, which includes more land. It found that the rate of warming was four times the global average about 20 years ago.

In contrast to the Finnish study, I found that there were two long periods, from the mid-1980s to the mid-1990s, and in the 2000s, with large jumps in warming in the region. “It’s not constantly changing, it’s changing in steps,” said Manvendra K. Dube, an atmospheric scientist at Los Alamos and one of the study’s authors.

Dr. said. Dube says the step-like increases suggest that in addition to the effects of increased greenhouse gas emissions from human activity, natural climate fluctuations may also play a role in the region’s warming.

Dr. Rantanen said his group’s findings also point to natural variability as having some effect on the rate of warming, and possibly some long-term changes in the ocean or atmospheric circulation.

He said it is clear that the interaction between water and ice temperature is the most important, especially in regions such as the Barents Sea where the rate of warming is even higher.

“Global warming trends are strongly coupled with reduced sea ice,” he said. “It is the highest percentage above those areas where sea ice is retreating the most. This is the main reason.”