Is climate change causing extreme cold? the debate is super hot


The data is clear: Rising global temperatures mean winters are getting milder, on average, and the kind of record-breaking cold that hit the country on Friday is becoming rarer. But at the same time, global warming may be altering weather patterns and pushing severe bouts of polar air into normally mild climates, according to scientists who are actively debating the link.

Drastic changes in the Arctic, which is warming faster than anywhere else on Earth, are at the center of the discussion. Changes in Arctic ice and snow cover are causing weather patterns that allow polar air to spread south more frequently. according to recent research.

“We’ve seen basically the same situation for the last three years in a row,” said Jennifer Francis, a senior scientist at the Woodwell Climate Research Center in Massachusetts. “Here we go again.”

But understanding any link between global warming and extreme cold remains a work in progress. Many Climate scientists still stress that even if frigid air escapes from the Arctic more frequently, that air will become warmer over time.

More than a million without power as frigid air grips the eastern US.

The debate began with a research paper Francis co-authored in 2012. It is revived whenever an extreme cold event makes headlines, such as in 2021, when the Texas power grid was overwhelmed by a storm that killed 246 people.

Francis’ research hypothesized that the warming of the Arctic was reducing the contrast between polar and tropical temperatures, weakening the jet stream, a band of strong winds in the upper atmosphere that helps guide weather patterns. A weaker jet stream would allow weather systems to swing more easily from the Arctic toward mid-latitude regions that typically have temperate climates.

Since then, observations of jet stream patterns have not confirmed the hypothesis, said Daniel Swain, a UCLA climate scientist. But the research inspired a series of follow-up studies that Swain hopes will eventually clarify a link between climate change and outbreaks of cold weather.

“We’re 10 years into this conversation and there’s still a lot of mixed feeling in the scientific community, although there’s some tantalizing evidence that there’s something ‘out there,'” said Swain, who works at the UCLA Institute for Environment and Science. Sustainability.

A 2021 study published in the journal Science is a new point of debate. The research explains what author Judah Cohen called “a physical basis” linking Arctic warming and changes in weather patterns.

It focuses on the polar vortex, an area of ​​low pressure typically stationed above the North Pole and surrounded by a band of fast-flowing air. Cohen likens it to a top: when the polar vortex is strong, that band of air spins in a tight circle.

Keep an eye out for dropping iguanas as temperatures drop.

More and more often, Cohen discovered, the polar vortex weakens like a wobbling top. That gives the circulating air a longer, more extended shape and encourages gusts of air from the Arctic to spread south.

While the polar vortex took that stretched shape for about 10 days a year in 1980, it has been happening more than twice as often in recent years, said Cohen, director of seasonal forecasting at Atmospheric and Environmental Research.

The research links that to changes in the climate around the Arctic: In the Barents and Kara seas north of Russia and Scandinavia, waters have warmed and ice has melted, while in Siberia, there has been a trend to cooling due to increased climate-induced snowfall. change.

Some scientists say a longer, more complete record of data is needed to support Cohen’s research and that there isn’t enough evidence to blame Arctic warming for cold spells at lower latitudes.

The surprising reasons why parts of the Earth are warming more slowly

Swain predicted that scientists will understand atmospheric dynamics, but that it could take years.

“It’s one of the most complicated issues in climate science,” Swain said.

In the meantime, the researchers are confident that the cold extremes will follow broader global trends and gradually warm, although they will still have a significant impact in places not used to cold.

“We are going to break a lot of records this week for sure,” Francis said. “The probability of breaking cold records is decreasing, and we see it in the data.”

And Cohen said the data suggests relief from the cold in the United States is near: Climate models agree that the polar vortex will return to its oblong shape in early January, once again trapping the frigid air around the North Pole. .

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