The basic idea, he said, is that warmer conditions create larger, more energetic waves in the atmosphere that make the jet stream more undulating, with larger peaks and troughs. This affects the rotation of the polar vortex.
To use the spinning top analogy, he said, “It’s like he’s starting to fuss with things.” “It loses its nice round shape and in this case it becomes more stretchy.” One lobe extends to Canada and the United States, bringing cold weather to the fore.
Dr. Cohen said he has been studying the topic since 2005, and is more confident than ever in the connection to changes in the Arctic. “The evidence is only mounting,” he said.
Other scholars aren’t so sure. in a brief paper In the journal Nature Climate Change in 2020, two researchers at the University of Exeter in England write that despite continued warming in the Arctic and loss of sea ice, short-term trends in cold extremes, the jet stream, and other climate-related measurements are in The 1990s and 2000s “didn’t last the last decade”, weakening the argument that warming in the Arctic was the culprit.
Some experts suggest that instead of warming, other naturally changing elements in Earth’s climate may be influencing the vortex. Among these, said Ted Shepherd, a climate scientist at the University of Reading in England, are sea surface temperatures in the equatorial Pacific, which can lead to changes in Arctic air masses that disrupt the jet stream and eddy.
Will this debate be resolved?
Scientists say questions about the role a warming Arctic could play in extreme cold spells is an example of the kind of healthy climate change debates happening now. It’s not about whether climate change is real – that question has been answered – but what kinds of impacts are taking place, how severe they are and whether they will get worse as warming continues.
Most scholars view this debate as an important debate that is still ongoing. Some aspects, Dr. Vavros said, “have very solid physical foundations”. Among these, he said, was the idea that the warming of the Arctic, by reducing the difference in temperatures between the Arctic and the tropics, had weakened the winds of the jet stream. But there are other aspects, including whether warming is making the jet stream more rippled and where, “are the things we’ve been really grappling with and we’re still uncertain,” he said.
“In the early days there was a lot of black and white thinking, including among people like myself, about this question,” Dr. Vavros added. “As more and more evidence emerges, there are clearly many shades of grey.”
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