Why is the south so cold when the planet is warm? Here’s What We Know.

Unusually cold air coming down from the North Pole brought the first thunderstorm warnings to southern Louisiana and Houston flights. Freezing storms could blast the country with heavy snow from the Northeast down the Gulf Coast this week.

What causes the sudden cold? The polar vortex. And it could be weird because of climate change, although not all researchers agree.

A polar vortex is a swirling mass of cold air that typically sweeps across the Arctic. It is stronger in winter, when the Northern Hemisphere moves away from the sun.

Generally, the polar jet stream, a strong group of air that circles the Earth and blows from west to east, hits the vortex and keeps it in northern latitudes, an area more accustomed to cold temperatures. However, as the storm weakens, the cold air can blow up and move south.

Temperatures could drop by dozens of degrees within hours and snow could hit parts of the US like Florida and Texas, known for better weather. The cold air may remain for several days until the Arctic vortex returns.

In a warming planet where global warming is the hallmark of climate change, scientists agree that we will continue to see unusually cold temperatures. A 2021 study suggested that changes in the Arctic, which is warming twice as much as the rest of the world, could stretch the polar vortex and make the jet stream more volatile.

“Climate change has increased the disruption of the polar vortex,” said Judah Cohen, study author and atmospheric scientist at Atmospheric Environmental Research, a climate research consulting firm.

While cold weather events have generally decreased in the United States since the 1960s, Dr. Cohen in a study in 2023 that, since the year 2000, the prevalence of cold air has increased, but still not enough to be considered a trend.

But research continues as Dr. Cohen.

“We don’t see a dramatic increase in extreme cold events,” Zeke Hausfather, a climate scientist at Berkeley Earth, a research organization, said last week. “If anything, they’re shrinking.”

Total snow is also expected to decrease. “What we expect is that, as things warm up, you can expect the total amount of snow to decrease over time,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies.

This week’s Arctic outbreak highlights the growing dangers of warming, especially in areas where they are not used to it. Cold weather deaths in the United States have more than doubled in the last two decades. In 2022, more than 3,500 people will die from cold-related causes, according to a study by the Centers for Disease Control and Prevention.

At least two frost-related deaths have been reported in Austin, Texas.