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According to climate scientists, the snowstorm that decimated the South this weekend and left thousands without power was likely caused by climate change.
It’s a counterintuitive suggestion, because greenhouse gases are trapping heat and causing higher average temperatures. Sometimes winter weather is more mild as a result. North America, especially the East Coast, is seeing colder winds blow in more frequently as a result of Arctic warming. This is because two phenomena are being distorted: the jet stream (a band of air flowing east to west) and the polar vortex (a wintertime area of colder air near the North Pole).
“When we get a snowstorm hitting the Southeast like this, it’s always because there’s a big southward dip in the jet stream, basically over the Mississippi Valley, that’s the underlying cause of the snowstorm in that region, and kind of all along the East Coast,” Jennifer Francis, senior scientist at Woodwell Climate Research Center in Massachusetts, told Yahoo News. “When it dips southward like that, the Arctic air, the very cold air, can also penetrate very far south.”
This could be because the Arctic is warming faster that the rest of the Earth. The jet stream is powered primarily by the temperature differential between the Arctic Region and other regions. A weaker jet stream can be diverted more easily if there is a decrease in temperature.
“Climate change is causing the jet stream to take more of these southward dips and northward swings,” Francis said. Each southward dip leads to a rebound and a subsequent northward swing. Extreme weather events, such as storms and cold snaps, can also be accompanied by dry spells or heat waves in other locations.
“Out West right now, they’re dealing with, actually, a very dry situation, warm conditions, and these two things always go hand in hand,” Francis said. “We see these bigger swings in the jet stream linked to climate change, and when they happen we always get unusual weather conditions. You can think back on the Texas cold spell of February and the Pacific Northwest heat wave of summer. It’s always one of these convoluted patterns in the jet stream that causes these things.”
The other climate-change-related reason for colder winter weather is that the polar vortex can get stretched out or split, making cold spells in North America and Eurasia more intense and longer lasting. “Right now we’re seeing the polar vortex being stretched a bit, and a lobe of it is coming down over eastern North America, which is strengthening this cold spell,” Francis said.
Francis said that recent research shows that disruptions of the Polar Vortex are more frequent now, and that the cause may be loss of Arctic Sea Ice. She likened polar vortex to spinning top. It tilts if you poke it. Due to climate change, an emerging heat bubble over the Barents Sea near Norway and Russia “acts just like poking that top,” she explained. “It can cause the top to not just wobble, but collapse completely.”
Although scientists agree that global warming is responsible for extreme summer weather such as heat waves and other extreme weather events, it remains controversial to determine if climate change has an impact on winter weather.
“Everybody agrees that when the polar vortex is disrupted, you get an increase in extreme winter weather. The big [question] is: Can changes in the Arctic affect the polar vortex?” Judah Cohen, director of seasonal forecasting at Atmospheric and Environmental Research (AER), a firm that helps businesses and governments manage climate risks, told Yahoo News. “I’m in the camp that says, yes, absolutely.”
A Science publishes paperCohen was the lead author on the study last year. He found that Arctic heating is causing more extreme winter weather across the United States. “The United States and other regions of the Northern Hemisphere have experienced a conspicuous and increasingly frequent number of episodes of extremely cold winter weather over the past four decades,” Cohen and his colleagues wrote.
Southerners have witnessed this firsthand. 13 inch snowfalls were recorded reportedBoone, N.C. and 8 inches in Spartanburg. AnsweredMore than 600 car accidents. Duke Energy, an energy utility, reported that there were more than 600 car crashes. Over 67,000 customersCarolinas experienced power outages.
“We show [in that paper] that there’s been a very strong, increasing trend in these episodes where the polar vortex stretches, or it kind of acts like a rubber band, or taffy, where it gets pulled apart, so the polar vortex then extends,” Cohen told Yahoo News. “Then the winds around the polar vortex go to much further southern latitudes. It heads towards the equator, and cold air and snowstorms occur when that happens.”
Last February saw millions of Texans affected by a series unusually severe winter storms. Without power or running water, Scientists noteIt was caused by Arctic warming’s effects on the jet stream and polar vortex. “It’s the same mechanism as the Texas freeze,” Cohen said Tuesday about the recent snowstorm.
Climate change can also lead to stronger snowstorms due to increased precipitation and ocean heating. Warmer weather can lead to heavier rainfall and more evaporation, while warmer ocean temperatures can lead to more severe storms. It can also lead to stronger winter storms, including snowstorms, as it can lead in summer to more heavy rains and hurricanes.
These trends will only get worse if greenhouse gas emissions continue to rise.
The storm that decimated the South is now making its way north, dumping Snowfalls up to a meterIn parts of the Northeast. That region has experienced increased snowfall in recent years due to Arctic warming, according to research by Francis, Cohen and Karl Pfeiffer, a colleague of Cohen’s at AER. According to Snowfall Reports, Atlanta, Boston, Des Moines, Detroit, New York, Salt Lake City, Seattle, Washington, D.C., and Salt Lake City are among the cities that have seen significantly more snowfall. A 2018 paperPublished by the trio in Nature.
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Global temperatures have been rising for decades. Look at the data to see how climate change is occurring.
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