Warming Arctic due to climate change has increased the number of polar vortex outbreaks, new study finds, when frigid air from the Far North bathes central and eastern United States in deadly cold .

The warming of the Arctic caused by climate change has increased the number of polar vortex outbreaks, when the frigid air from the far north bathes the central and eastern United States in deadly cold, according to a study.

The study published in the journal Science Thursday is the first to show links between changes in the polar region and the Valentine’s Day freeze in February that triggered widespread power outages in Texas, killing more than 170 people and causing at least $ 20 billion in damage.

The polar vortex normally keeps the icy air trapped in the Arctic. But the warmer air weakens the vortex, allowing it to stretch and move south. The number of times it has weakened per year has more than doubled since the early 1980s, said lead author of the study, Judah Cohen, winter storm expert for Atmospheric Environmental Research, a trading company. located outside of Boston.

“It is counterintuitive that a rapidly warming Arctic could lead to an increase in extreme cold in a place as south as Texas, but the lesson of our analysis is to expect the unexpected with climate change. “Cohen said.

Climatologists are still wondering how and if global warming affects cold snaps – they know it reduces the total number of cold days, but they’re still trying to figure out if it leads to deeper cold snaps.

Cohen’s study was the first to use measurements of changes in the atmosphere to help explain a phenomenon that climate models had struggled to explain.

Cohen’s study “provides a potentially simpler interpretation of what’s going on,” said Michael Mann, a climatologist at Pennsylvania State University, who was not part of the study.

Cohen was able to show how there have been dramatic differences in the warming within the Arctic itself, which explains how the polar vortex can stretch and weaken.

When the area north of England and around Scandinavia warms more than the area around Siberia, it expands the polar vortex eastward and cold air moves from Siberia northward over the region polar, then south into the central and eastern United States.

“The Texas cold blast of February 2021 is an illustration of the link between a changing Arctic and cold gusts in lower latitudes,” said climatologist Jennifer Francis of the Woodwell Climate Research Center in Cape Cod. She helped start the Arctic Link Theory, but was not part of Cohen’s research. “The study takes this controversial hypothetical link and firmly shifts it to accepted science,” she says.

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Follow Seth Borenstein on Twitter at @borenbears.

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This Associated Press series was produced in partnership with the Department of Science Education at Howard Hughes Medical Institute. The AP is solely responsible for all content.

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