by Much of the United States is shivering with brutal cold as most of the rest of the world is feeling unusually warm weather. Curiously, however, that contradiction fits neatly into explanations of what climate change is doing to Earth, scientists said.
In a map of global temperatures over the past few days, large chunks of the world – the Arctic, Asia, parts of Africa, the Middle East and South America – appear as dark red, meaning more than a dozen degrees Fahrenheit (7 degree Celsius) warmer than the late 20th century average. But the United States stands out like a cold sore thumb—a deep blue-purple that’s just as outdoorsy as it is on the frigid side.
Wind chills in parts of North Dakota reached minus 70 degrees (minus 56 degrees Celsius), while the heat index in Miami was more than 160 degrees warmer at 92 (33 degrees Celsius). The fourth coldest NFL football game took place in Kansas City, and across the globe the thermometer hit a blistering 92 degrees, 12 degrees (6.8 degrees Celsius) warmer than average on Friday during tennis’ Australian Open in Melbourne. Hot temperature records fell overnight in Aruba, Curacao, parts of Argentina, Oman and Iran.
When the weather was warmer than usual, it was happening in the southern hemisphere, which is in summer, and in the northern hemisphere, which is in winter. For example, northern Oman had its hottest January night ever at 79.5 degrees (26.4 degrees Celsius). Argentina, in the south, had a record for the hottest January night at 81.1 Fahrenheit (27.3 Celsius).
If it seems like the world has come to an end, it kind of is. Because all this comes from what is happening in the Arctic, where it has been warming twice as fast as the rest of the planet. Now, it’s warming three or four times faster.
“When the Arctic is warm (as it is now), we’re more likely to see places like Texas that are not well equipped to deal with it,” said Jennifer Francis, a Woodwell Research Center climate scientist. and a pioneer in the Arctic Amplification theory, which links the cold outbreaks to climate change. “Rapid Arctic warming is one of the clearest symptoms of human-caused climate change, making winter extremes even more likely as the globe warms overall.”
The way the cold is invading is through a weather phrase that is becoming increasingly familiar to Americans: The white vortex. It is a weather term that dates back to 1853 but has only been used frequently in the last decade or so.
That could be because the icy stabs are happening more often, said winter weather expert Judah Cohen of Atmospheric Environmental Research, a commercial firm outside Boston.
The polar vortex is a strong, icy mass that typically lingers over the top of the planet, buffeted by strong winds that blow around it, Cohen said.
It’s like an ice skater spinning fast with her hands stuck in, he said. But when the white vortex weakens, the hands start to stick out, the skater slips and “all the cold air is then released from the center of the white vortex,” Cohen said.
The current cold outbreak is consistent with the Arctic shift and the polar vortex, Cohen said. “What we found is that when the white vortex stretches like a rubber band, severe winter weather is more likely in the United States. That’s where it’s usually focused and in January we have a really big case of that extension of the white vortex.”
This one is stronger and may last longer than most, Cohen said.
Cohen and others have done studies showing that white vortex outbreaks have become more frequent in recent years.
The idea is that the jet stream — the upper air circulation that drives the weather — is brighter with increased global warming, said University of Wisconsin-Madison climate scientist Steve Vavrus. And those wave changes in the upper air push the polar vortex out of place and toward the United States, Cohen said.
It’s a theory that is still being debated by climate scientists but is becoming more and more accepted. Originally, Vavrus and Francis theorized that barometric pressure changes were caused by the melting of sea ice in the Arctic. Now many scientists say it’s more complicated, but still tied to climate change and supercharged warming in the Arctic, with other factors like Siberian snow cover and other atmospheric waves also playing a role.
“The most important thing for me right now is that Arctic Amplification is happening and it has complex interactions within our climate system. “Winter will always bring us cold weather, but like the warm season it may be changing in ways we understand and ways we’re still learning about,” said University of Georgia meteorology professor Marshall Shepherd. Contrary to the Vegas slogan, what happens in the Arctic doesn’t stay in the Arctic.”
Think of what’s happening as an orchestra playing a symphony, and “what’s driving all those orchestral instruments is a planet,” said Northern Illinois University meteorology professor Victor Gensini.
Gensini and Cohen said this cold snap in the United States will subside in a few days and be replaced by unusually warm weather, due to climate change. But another polar vortex looks like it’s coming at the end of the month, though not as strong as this one, they said.
Despite the US cold, the Earth’s global average temperature continues to flirt with daily, weekly and monthly records, as it has for more than seven months. That’s because the United States is only 2% of the Earth’s surface, scientists said.
“A place like Chicago or Denver or Lincoln, Omaha, Oklahoma City, Dallas, Houston, I mean we’re experiencing it,” said Gensini, who said the temperature outside his window Tuesday was 6 below . “We’re just an isolated pocket if you look globally.”
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