How global warming could actually make winters colder for some people

As Arctic winters become increasingly balmy, North America and Europe may experience more frequent cold snaps.

That’s according to a new international study, published Wednesday in the journal Nature Climate Change. Researchers find that rapid warming in the Arctic – which has occurred at two to three times the pace of the rest of the Northern Hemisphere – may be exacerbating the effects of the jet stream.

Depending on its position and intensity, the jet stream can cause extreme cold weather in the mid-latitudes. Recent winter records – such as New York’s 2014/15 snowfall – may be attributed to changes in the jet stream.

Current research suggests that a “wavier” jet stream may correlate to severe climates south of the Arctic, which may linger for several weeks at a time. When the jet stream’s route is more direct from west to east, typical winter weather seems to follow.

“We’ve always had years with wavy and not so wavy jet stream winds, but in the last one to two decades the warming Arctic could well have been amplifying the effects of the wavy patterns,” co-author Edward Hanna, a professor of climate change at the University of Sheffield, said in a press release.

Over the past few decades, different regions around the world have warmed at different rates. In the Arctic region, temperatures are rising faster than they are at mid-latitudes. As the temperature contrast between those two regions becomes smaller, the jet stream becomes weaker.

In 2014, The Christian Science Monitor’s Pete Spotts explained:

The jet stream is a river of high-altitude winds that steers and spawns storms and in effect serves as an atmospheric boundary for cold Arctic air. A slower jet stream produces longer meanders… This would bring cold air farther south and warm air farther north than otherwise would be the case.

A related study, published Monday in the same journal, found that the Arctic polar vortex has been shifting from North America toward Europe over the course of several decades. That shift has pushed Arctic air southward, researchers said, bringing colder winters to Europe and North America.

The finding may present a new opportunity for climate researchers to predict the jet stream's behavior, researchers say. In turn, that could improve long-term models for winter weather in highly populated regions.

“This would be hugely beneficial for communities, businesses, and entire economies in the northern hemisphere,” Dr. Hanna said. “The public could better prepare for severe winter weather and have access to extra crucial information that could help make live-saving and cost-saving decisions.”