Dreaded Polar Vortex May Be Shifting
As the Arctic wind pattern migrates toward Europe it could allow frigid air to descend upon the U.S.
By Scott Waldman, ClimateWire on October 25, 2016
Credit: BENJAMIN LIPSMAN Flickr (CC BY 2.0)
The polar vortex in recent years has brought the kind of miserable cold to northern states that made it hard to breathe outside. We’re probably in for more of the same.
That’s the finding of a new study published yesterday in the journal Nature that finds that as the Arctic warms, it is shifting the polar vortex to Europe. That in turn will bring more bursts of frigid cold to North America.
Those temperature drops could lead to miserable days in February and March, the research finds. Conversely, those drops in temperature could offset some of global warming’s effect in those regions, said Martyn Chipperfield, professor of atmospheric chemistry at the University of Leeds and a co-author of the paper.
“Climate change can lead to extremes; it’s not like a regular change, everyone to the same extent at all times and places,” he said. “Despite the overall warming, you can get in places like the Northeastern U.S. extreme cold events. That’s consistent with climate change and global warming.”
The polar vortex is a fast-moving band of air that encircles the frigid Arctic in winter months and traps it there. Its movement is part of a decadeslong change.
The polar vortex has actually “shifted persistently” away from North America and into Europe and Asia over the last 30 years, researchers found. That results in cooling over North America but warmer winters in Europe.
As global warming decreases sea ice, the sun’s warmth absorbed by the ocean is instead released from the ocean for a longer period of time, which disrupts the vortex.
When the vortex weakens, a growing number of climate scientists argue, the cold Arctic air migrates to lower latitudes, as happened in early 2014 and 2015. The sudden and somewhat prolonged burst of cold broke pipes and water mains and more than doubled energy bills in places like New York and New England as it wreaked havoc across a wide swath of the country.
The movement of the vortex has come as the Arctic steadily loses sea ice, a process that some scientists are worried could accelerate in the future as the Earth continues to warm at record levels.
The loss of sea ice in the Arctic amid rapid warming has also weakened the vortex, said Judah Cohen, a climatologist with the private firm Atmospheric and Environmental Research. Cohen has said that weakening will lead to increasingly frigid periods of winter in North America, though other scientists dispute his claims. Though he has not studied a shift in the vortex itself, he said it could be consistent with his findings that the vortex is weakening.
“In general, a vortex that has shifted is a vortex that is weaker,” he said. “They’re consistent.”
Monthly global temperatures continue to set warmth records, but North America and Europe have seen extreme cold during some winter days as a result of the polar vortex. However, researchers found, the cold air brought into lower latitudes by the vortex has also offset global warming temperatures.
Still, don’t expect prolonged periods of cold every winter, Chipperfield said. Climate change increases periods of extreme weather, but that doesn’t mean every winter will bring the effects of the polar vortex, he said.
“You can get regional occurrences of cold temperatures despite what we think is an overall move to a warmer climate,” he said, adding, “Climate change can lead to more extreme events, not just a shift in the average.” Reprinted from ClimateWire with permission from Environment &