Warm Arctic, Cold Continents? It Sounds Counterintuitive, but Research Suggests it’s a Thing

https://insideclimatenews.org/news/20112020/warm-arctic-cold-continents-climate-change

 

By Bob Berwyn, InsideClimate News
Nov 22, 2020

By any measure, the Arctic has changed profoundly in the last 40 years, warming three times as fast as the global average, and losing half its summer sea ice, as well as billions of tons of land-based glacier ice.

And even though the Arctic only encompasses about 6 percent of the Earth's surface area, the warming there has kicked off climate chain reactions that are disrupting weather and climate patterns across the mid-latitudes of the Northern Hemisphere, including most major North American and European cities and agricultural areas. The abrupt and accelerating Arctic warming directly harms the communities, livelihoods and traditions of the 4 million people who live in the polar region.

Some scientists say a more frequently recurring cycle they refer to as "warm Arctic, cold continents," is a sign of that disruption. The pattern seemed to emerge as a global warming signal about 10 years ago, as researchers documented an increase of summer and winter extremes in parts of North America and Eurasia, including heat waves, killer blizzards, floods and cold snaps, occurring even as Arctic warming and ice loss accelerated.

•••••

"In general we do see the tendency that, when the Arctic is very warm, you're displacing the cold air that is usually over the Arctic to somewhere else," said co-author Jennifer Francis, a climate researcher with the Woodwell Climate Research Center. "As the arctic warms faster we expect to see this more."

•••••

Cohen said he considers complex atmospheric movements involving the polar vortex to be a key link between the warming Arctic and extreme cold events in North America and Eurasia. The polar vortex is a belt of winds around the Arctic that keeps cold air bottled up if it's tight, but spills frigid air masses southward when disrupted.

That disruption happens, he said, when the warm Arctic air works its way high into the upper atmosphere, where it crests like a wave to break through the vortex.

"It's getting increasingly difficult to get severe winter weather into the mid-latitudes without a polar vortex disruption," he said. "And amplified Arctic warming is favorable for disrupting the polar vortex."

Francis, of the Woodwell center, added that it's important to remember that the overall hypothesized impact of amplified Arctic warming is "to favor an increase in the persistence of weather conditions, including cold spells, heat waves, dry periods and storminess, all of which can be disruptive if they last long enough."

Those patterns, she said, can last a week to several weeks and they can flip suddenly: "The whiplash from a record-breaking heatwave to cold and snow that occurred in the western states (particularly Rockies) this fall was a great example."

tags: extreme weather, severe weather,