It is as if the world has turned upside down, or at least its climate. You can blame the increasingly familiar polar vortex, which has brought a taste of the Arctic to places where winter generally requires no more than a jacket.
Around the North Pole, the ultra-cold winter air is usually kept bottled up to 15 to 30 miles in height. This is the polar vortex, which rotates like a rotating top at the top of the planet. But occasionally, something hits the top, sending cold air from your home in the Arctic and heading south. It has happened more often, and scientists are still unsure of why, but they suggest that it is a mix of random natural climate and man-made climate change.
This collapse of the polar vortex in particular has been incredible. Meteorologists call it one of the biggest, most unpleasant and most enduring that they have ever seen, and have been watching it since at least 1950 s. This week’s weather is part of a pattern that dates back to January.
“It was a huge breakdown,” said Jennifer Francis, a climate scientist at the Woodwell Climate Research Center in Cape Cod. “It is really the cause of all these crazy weather events in the northern hemisphere.”
“It’s been unusual for a few weeks – very, very crazy,” said Francis. “Totally upside down.”
REGISTER COLD IN HEATING PLACES
Record-below-zero temperatures in Texas and Oklahoma took millions off the grid and froze deeply. A deadly tornado hit North Carolina. Other parts of the South saw snow and reports of something that looked like a snow tornado, but it wasn’t. The snow fell hard not only in Chicago, but in Greece and Turkey, where it is much less normal. The record cold also hit Europe this winter, earning the name “Beast of the East”.
“We had everything you could imagine last week,” said Victor Gensini, a professor of meteorology at Northern Illinois University, noting that parts of the United States are 50 degrees (28 degrees Celsius) cooler than normal. “It’s been a wild ride.”
It was hotter on Tuesday in parts of Greenland, Alaska, Norway and Sweden than in Texas and Oklahoma. And somehow people in South Florida have been complaining about the record heat that is causing plants to bloom earlier.
In the city of Tasiilaq, in eastern Greenland, it is about 18 degrees (10 degrees Celsius) warmer than normal, “which is a bit of a nuisance,” said Lars Rasmussen, curator of the museum at the local cultural center. “The warm climate makes dog sledding and snow scooters a little uncomfortable.”
Several meteorologists have openly blamed the breaking or interruption of the polar vortex.
This used to happen once every two years or so, but research shows that they are now close to happening annually, if not more, said Judah Cohen, a winter storm specialist at Atmospheric Environmental Research, a trading company outside Boston.
THE SPINNING TOP IS FULLY
The polar vortex spends the winter in its normal place until an atmospheric wave – the type that brings weather patterns here and there – hits it. Typically, these waves do not affect the strong vortex much, but occasionally the wave has enough energy to push the top, and that is where the cool air comes out, said Gensini.
Sometimes the mass of cold air splits into pieces – an event that is usually connected to major snowstorms in the eastern United States, such as a few weeks ago. Other times, he just moves to a new place, which usually means intense cold in parts of Europe. This time, he did both, Cohen said.
There was a vortex split in early January and another in mid-January. Then, at the end of January, there was the displacement that caused cold air to spill over Europe and much of the United States, Cohen said.
Both Cohen and Francis said that this should be considered not one, but three interruptions of polar vortexes, although some scientists put it all together.
While both the vortex and the wave that hit it are natural, and the disruptions of the polar vortexes occur naturally, there is likely to be an element of climate change at work, but science is not sure to agree with that, said Cohen, Gensini and Francis.
Warming in the Arctic, with shrinking sea ice, is affecting the atmospheric wave in two places, giving it more energy when it reaches the polar vortex, making it more likely to rupture, Cohen said.
“There is evidence that climate change may weaken the polar vortex, which allows icy air from the Arctic to leak into the Lower 48,” said Marshall Shepherd, professor of meteorology at the University of Georgia.
THE STANDARD HAS BEEN OBSERVED FOR DECADES
There were strong disruptions of polar vortexes and outbreaks of cold like this in the 1980s, Cohen said.
“I think it’s historical and generational,” said Cohen. “I don’t think it’s unheard of. This outbreak in the Arctic must be thought of in context. The globe is much hotter than it used to be. “
It also looks colder because just before the outbreak, much of the United States was experiencing a milder-than-normal winter, with the soil not even frozen on Christmas Day in Chicago, said Gensini.
The globe as a whole has approximately the same temperature as the average was from 1979 to 2000 for this time of year, according to the University of Maine Climate Reanalyzer. This is still hotter than the 20th century average, and scientists don’t think this month is likely to be colder than the 20th century average for the globe, something that hasn’t happened since the early 1980s.
One reason is that it will soon return to normal when the polar vortex returns to its normal home, Cohen said.
As for people who think this cold spell belies global warming, scientists say it definitely is not.
Even with climate change, “we will still have winter,” said North Carolina climatologist Kathie Dello. “What we are seeing here is that we are not prepared for almost all types of extreme weather. Is very sad. “
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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 Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.