Arctic warming is happening significantly faster than previously thought, study finds




  • In Science
  • 2022-08-11 19:19:14Z
  • By NBC News
 

Things are heating up at the top of the world about four times faster than the rest of the globe, according to new research on the Arctic, where some of the most dramatic effects of climate change are already playing out.

Previous studies - which have evaluated data over longer time periods - had estimated that the Arctic region is warming twice as fast as the global average, a phenomenon known as Arctic amplification. But scientists at the Finnish Meteorological Institute now say that since 1979 the Arctic is actually warming at a significantly faster rate than that.

In some spots, the researchers found that warming has been even more pronounced in recent decades. The area around the Barents Sea, for instance, has warmed seven times faster than the global average, they said.

"Our results demonstrate that climate models as a group tend to underestimate the observed Arctic amplification in the 1979-2021 time period," the scientists wrote in the study, which was published Thursday in the journal Communications Earth & Environment.

Climate researchers often use the situation in the Arctic as a bellwether for the impacts of global warming because the region is particularly sensitive to even small shifts in global surface temperatures. As a result, changes there typically play out more rapidly compared to elsewhere on Earth. What happens in the Arctic also has enormous implications for the rest of the globe, since melting ice sheets contribute to rising sea levels.

In the new study, the researchers focused on the area inside the Arctic Circle, an imaginary demarcation approximately 66 degrees north of the equator. The scientists used data from the past 43 years to observe changes within this region, which includes parts of Russia, Norway, Sweden and Finland, most of Greenland and the northernmost reaches of Canada and Alaska.

"We focused on a period that began in 1979 because the observations after that year are more reliable and because strong warming began in the 1970s," study co-author Mika Rantanen, a researcher at the Finnish Meteorological Institute, said in a statement.

Rapid losses of sea ice and sea ice thickness, and shortening snow seasons observed in the Arctic in past decades punctuate the research findings, said Richard Thoman, an Arctic climatologist with the International Arctic Research Center, who was not involved in the new research.

"Since the late '70s, the changes have really been accelerating," Thoman said. "The change since 1979 is very solid. It's not just based on one data set."

Previous evaluations about the rate of Arctic warming have assessed the pace of warming using the 1800s or early 1900s as a starting point. These analyses remain accurate, experts said. What's new here is that the pace of warming has increased dramatically in recent decades and that climate models might be underestimating that effect.

"While the Arctic warmed a little over two times more than the global average since the 1800s (the 'two times faster' value often reported), it's also true that the Arctic warmed about four times faster than the global average when looking at the period since the 1970s," Kyle Armour, an associate professor and climate scientist at the University of Washington who was not involved in the study, said in an email.

As the world warms from heat-trapping greenhouse gas emissions, sea-ice cover in the Arctic shrinks. This causes the Arctic Ocean to absorb sunlight that would otherwise be reflected off the ice, which in turn causes more warming.

While Arctic amplification is driven in part by natural, long-term variations, scientists have said it is greatly exacerbated by human-caused global warming.

Still, the exact rate of warming in the Arctic had been difficult to pin down and the current study found that existing climate models are not accounting for the faster-than-expected pace of change. Determining that rate, and how it compares to the rest of the globe, depends on what researchers define as "the Arctic," and how far back they comb through temperature records.

"While the magnitude of Arctic amplification is dependent to some degree on how the Arctic region is defined, and by the period of time used in the calculation, the climate models were found to underestimate Arctic amplification almost independent of the definition," Rantanen said in the statement.

The findings appear in line with other recent studies of changes in the region. A report published last month by the nonprofit conservation group Polar Bears International found that the thickness of Arctic sea ice in some areas has thinned by more than 6 feet since the middle of the 20th century.

In 2020, a record-breaking heat wave scorched Siberia, bringing attention to the effects of climate change in one of the coldest regions of the planet. In June of that year, a weather station in Verkhoyansk, a Russian town in the Arctic Circle, reported a temperature of 100.4 degrees Fahrenheit, the highest daily maximum temperature recorded north of the Arctic Circle. A study of the Siberian heat wave that was published last year in the journal Climate Change found that it would have been "almost impossible" without human-caused global warming.

And the latest version of the National Oceanic and Atmospheric Administration's annual "Arctic Report Card," published in December 2021, found that "rapid and pronounced warming continues to drive the evolution of the Arctic environment." NOAA's assessment said the average surface air temperature over the Arctic from October 2020 to September 2021 was the seventh-warmest on record.

The new study further highlights the dire situation unfolding at the planet's northern pole.

"The import of this is that it highlights just how rapidly the Arctic system has been changing in the last 43 years," Thoman said. "It's changing much faster than the globe as a whole and it's changing much faster than the Arctic was changing before that."

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