A ‘Once in a Generation’ Storm. What’s the Role of Climate Change?

But many scientists say that while there is some evidence for the idea that Arctic warming weakens the jet stream, there is less to support the concept that this makes for a wavier pattern that allows for the polar vortex to wander. And at least one study has found that a short-term trend of a wavier jet stream and polar vortex excursions in the 1990s and 2000s, which prompted the development of the idea that Arctic warming affected the polar vortex, has not continued.

Research on the subject is continuing.

“We’ve figured out a few strands of this question,” said Steve Vavrus, a climate scientist at the University of Wisconsin who was an author of a 2020 paper that reviewed current understanding of the subject in a paper several years ago. “I think we’ll continue to do so in coming years as more and more people research it.”

Outside of the Arctic, warmer winters have many effects that are more certain. Higher winter temperatures in the Western United States, for example, have increased the survivability of tree-destroying insects like pine beetles, contributing to large scale die-offs in forests. Warming also means more precipitation falls as rain, rather than snow, reducing winter snowpack that in many areas is critical for water supplies.

When it is cold enough for snow rather than rain, however — as it was in many places during the recent storm — more snow can fall. That’s because air can hold more moisture when it’s warmer. It’s the cold-weather version of why rainfall is becoming more extreme in many parts of the world.

While it’s difficult to know whether this storm, overall, was snowier than it might have been without human-caused climate change, in some areas snow totals were off the charts. Buffalo received more than 22 inches of snow on Friday, a record, the local National Weather Service office said.

Buffalo is in a part of the country that’s subject to “lake effect” snow, which happens when cold, dry air blows across water (in Buffalo’s case, Lake Erie), picking up moisture that is then dumped as snow when it reaches land. Lake-effect snow occurs when the water is unfrozen. And, generally, the greater the temperature difference between the air and water, the greater the effect.