This week’s winter storm is part of a pattern caused by disturbances to the upper-atmosphere phenomena known as the polar vortex that can send icy blasts from the Arctic into the middle latitudes, chilling Europe, Asia and parts of North America. The disturbance and its effects have persisted for an unusually long time this year, said Jennifer Francis, a senior scientist at the Woodwell Climate Research Center, with two disruptions of the polar vortex so far this year and, potentially, a third on the way.
Research into the interplay of the complex factors that bring on blasts from the polar vortex is ongoing, but climate change appears to be part of the mix. While warming means milder winters overall, “the motto for snowstorms in the era of climate change could be ‘go big or go home!’” said Judah Cohen, director of seasonal forecasting at Atmospheric and Environmental Research, a company that provides information to clients about weather and climate-related risk.
The United States has already seen heavy snowfall in the Sierra Nevada and in the Great Plains in the past week. Last month, Madrid was buried under a paralyzing foot and a half of snow, and parts of Siberia suffered an unusually lengthy cold spell with temperatures of 40 degrees below zero Fahrenheit — and one area recorded a temperature of nearly 73 below. (Last summer, some of the same areas experienced record heat.)
The wild weather has its origins in the warming Arctic. The region is warming faster than the rest of the planet, and research suggests that the rising temperatures are weakening the jet stream, which encircles the pole and generally holds in that frigid air. In early January, a surge of sudden warming hit the polar stratosphere, the zone five to thirty miles above the surface of the planet.
When one of those “sudden stratospheric warmings” happens, it delivers a punch to the polar vortex that can cause the Arctic air to shift and to make its way down through the atmosphere to people who suddenly need to layer up and break out their shovels.