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Arctic change increased chances of tightly spinning winds above North Pole, authors say, boosting chances of extreme weather
The climate crisis has not only been leaving deadly heatwaves and more destructive hurricanes in its wake, but also probably creating extreme winter weather events, according to a new report released on Thursday by the American Association for the Advancement of Science's journal Science.
Climate change has long been associated with such extreme weather events as the hurricane that just struck the Gulf coast over the weekend, knocking out power for over a million people and leaving several people dead, and the deadly heatwaves across the Pacific north-west earlier this summer.
But scientists have long wrestled with the connection between the uptick in such severe winter weather events as powerful snowfalls and atypical cold snaps across the northern hemisphere, and accelerated Arctic warming, or Arctic amplification, one of the hallmarks of global warming.
The new report, titled Linking Arctic variability and change with extreme winter weather in the United States, has helped to clarify that connection.
Its authors argued that this type of Arctic change actually increased the chances of tightly spinning winds above the North Pole, known as the Arctic stratospheric polar vortex, being stretched and thus boosting the chances of extreme weather events in the US and beyond.
"I know it's very counterintuitive, and I think that's why there's a lot of resistance and hesitancy to our idea, right?" said Judah Cohen, one of the paper's authors. "Because how could making the Earth warmer lead to more extreme cold? But that's what we're arguing."
Cohen, who also serves as a visiting scientist at MIT and as director of seasonal forecasting at Atmospheric and Environmental Research, explained that he and his colleagues' work was prompted by the extreme snowstorm in Texas in February. After subfreezing temperatures clobbered the region, dozens died and more than 4m homes and businesses lost power.
While many, including the White House, attributed the event to climate change, Cohen said he believed this was the only paper that actually showed the connection between the cold wave and Arctic change, and demonstrated the physical mechanism surrounding all of this - the stretched polar vortex.
"When the polar vortex is nice and circular, that's a sign all the cold air is bottled up over the Arctic," said Cohen. "When it stretches like this, a piece of it goes into Asia and a piece of it goes towards eastern North America. So that's what we're seeing. And that was what happened with the Texas cold wave."
The process for putting together this report involved the authors conducting observational analyses of the stratospheric polar vortex over the past four decades. They also conducted numerical modeling, in which they used some of the same models experts utilized when predicting such weather events as Hurricane Ida.
In the future, the study's findings could have a major impact when it comes to warnings before extreme cold weather events.
The report explained: "The identification of the precursor pattern to stretching events can potentially extend the warning lead time of cold extremes in Asia, Canada and the United States."
It could also help policymakers, like those in Texas, who typically have not been focused on preparing their infrastructure and residents for extreme cold, start to make important and potentially life-saving arrangements before the next major storm.
"Preparing for only a decrease in severe winter weather can compound the human and economic cost when severe winter weather does occur, as exemplified during the Texas cold wave of February 2021," the report stated.
