Published: Thu, March 15, 2018
Business | By Tara Barton

Warming Arctic linked to extreme cold, heavy snow in U.S., study finds

Warming Arctic linked to extreme cold, heavy snow in U.S., study finds

While the study did not explain how the warmer Arctic is causing the more frequent and more extreme winter storms such as the recent strong of nor'easters, it did offer some possibilities that are supported by their data. Scientists know this warmer Arctic air destabilizes the jet stream - and when Arctic air is free to wander south, it leads to cold snaps in the USA or causes intense winter storms.

Since 1990, the eastern US has been visited by winter storms so severe that they earned highly dramatic nicknames, such as "Snowzilla", "Snowmaggeddon" and "Snowpocalypse".

This connection was especially strong for locations in the eastern third of the U.S., while the Rockies and locations on the West Coast showed a weaker or even opposite relationship.

How does this relationship work?

The results found that major winter storms were two to four times more likely when the Arctic is abnormally warm, compared to when it was abnormally cold.

Evidence is mounting that the answer could lie in the rapidly melting Arctic.

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These air-temperature changes close to the surface led to similar changes higher up in the atmosphere. The fact that warming leads to changes in the wind direction, and the next shift can bring to the Central part of mainland North America the cold air of the Arctic. "Warm temperatures in the Arctic cause the jet stream to take these wild swings, and when it swings farther south, that causes cold air to reach farther south".

And this disturbance of the polar vortex could end up shaping conditions that worsen winter weather in the U.S.

This research is timely given the recent severe winter weather experienced across the US and may help explain how climate change in general and Arctic change in particular are contributing to more severe winter weather despite an overall warming climate.

Richard Alley, a leading glacier and climate expert at Penn State who was not involved in the research, told the Guardian that the study is "fascinating" and "important", but added the discrepancy between Arctic temperatures and winter weather elsewhere could have other drivers, such as a warm Gulf of Mexico feeding extra energy into storms along the East Coast. The complexity of these systems is reflected in emerging disruptions that are likely the products of climate change, though there is still much to be learned about how climate change could shape weather patterns around the world, the study authors reported. "This paper argues that the weather was cold not in spite of climate change but likely because of climate change". "It was kind of expected that if you warm the Arctic, the only thing that's going to lead to is just milder temperatures everywhere - and that's not a complete picture".

The findings were published online today (March 13) in the journal Nature Communications.

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