Climate Signals summary: Evidence continues to mount that human-caused climate change can make winter weather worse - such as last weekend's southern snowstorm and February 2021's historic cold temperature outbreak.
The snowstorm that battered the South this weekend, leaving thousands without power, was likely exacerbated by climate change, according to leading climate scientists.
It’s a counterintuitive suggestion, because greenhouse gases are trapping heat and causing higher average temperatures. Sometimes winter weather is milder as a result. But in North America, especially the East Coast and the South, colder winds are blowing in with greater frequency because of how Arctic warming is distorting two phenomena: the jet stream, a band of air flowing west to east, and the polar vortex, a wintertime area of cold air near the North Pole.
“Climate change is causing the jet stream to take more of these southward dips and northward swings,” [Jennifer Francis, senior scientist at Woodwell Climate Research Center in Massachusetts] said. Each southward dip causes a rebound with an adjacent northward swing. So extreme weather events like cold snaps and storms in one location can be accompanied by dry spells and heat waves somewhere else.
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