One study finds that Arctic warming caused by climate change has increased the number of polar vortex outbreaks, when cold air from the far north bathes the central and eastern United States with deadly cold.
The study in the journal Science Thursday is the first to show the connections between changes in the polar region and the February Valentine’s Day freeze that caused widespread power outages in Texas, killing more than 170 people and causing at least $ 20 billion in damages.
The polar vortex normally keeps icy air trapped in the Arctic. But warmer air weakens the vortex, allowing it to stretch and wander south. The number of times it has weakened a year has doubled since the early 1980s, said study author Judah Cohen, a winter storm expert for Atmospheric Environmental Research, a trading company located outside of Boston.
“It’s counterintuitive that a rapidly warming Arctic could lead to an increase in extreme cold in a place as far south as Texas, but the lesson of our analysis is to expect the unforeseen with climate change,” Cohen said.
Climate scientists continue to debate how and if global warming affects colds – they know it reduces the total number of cold days, but they keep trying to understand if it leads to deeper colds.
Cohen’s study is the first to use measures of changes in the atmosphere to help explain a phenomenon that climate models had had difficulty explaining.
Cohen’s study “provides a potentially simpler interpretation of what’s going on,” said Michael Mann, a climate scientist at Pennsylvania State University who was not part of the study.
Cohen was able to demonstrate how there have been dramatic differences in warming inside the Arctic, leading to how the polar vortex can stretch and weaken.
When the northern part of England and around Scandinavia heats up more than the Siberian zone, the polar vortex extends eastward and cold air moves from Siberia northward over the polar region and then to south to the central and eastern part of the United States.
“The Texas Cold Blast of February 2021 is a child” because of the link between an Arctic shift and cold explosions at low latitudes, said Jennifer Francis, a climate scientist at the Woodwell Climate Research Center in Cape Cod. He helped pioneer Arctic link theory, but was not part of Cohen’s research: “The study takes this controversial hypothetical link and moves it firmly toward accepted science,” he said.
This Associated Press series was produced in collaboration with the Department of Science Education at the Howard Hughes Medical Institute. The AP is solely responsible for all content.