In this scenario, put forth by physicists at NASA's Jet Propulsion Laboratory, the rise in air pollution via coal emissions from China and Southeast Asia is to blame for the relentless snows that have blanketed parts of the United States.
NPR's Goats and Soda blog reports:
The animation from NASA [seen below] shows how pollution from Asia and other continents mixes and moves around the world. (It's a simulation made with satellite data from September 2006 to April 2007.)
About 43 seconds into the video, Asia comes into view ... large swaths of emissions from burning coal pulse from China and Southeast Asia in white. Sometimes the particles blow east and mix with storms above the Pacific Ocean. These storms can have a big effect on winter weather in the U.S., [according to NASA physicist Jonathan Jiang].
Storms in the Pacific move northwest; some hit the West Coast and cause rain and snow. Others end up far north in Canada, where they can alter the weather across the entire U.S., Jiang says.
As this 2014 scientific report by Jiang and colleagues notes, the extra pollution out of Asia makes clouds over the Pacific bigger and heavier.
"Atmospheric particles can serve as cloud nuclei and foster cloud formation," Jiang writes. The particles give water vapor something on which to condense.
Jiang isn't sure yet how much the bigger storms in the Pacific are to blame for cold, wet winters on the East Coast and drought in the West. His research team is working on models and computer simulations right now to look at such questions. "We have not reached a final conclusion yet," he writes.
Top image: Kim Taylor, of Norwood, Mass., shovels a path in the snow in front of her home Sunday, Feb. 15, 2015. A storm brought a new round of wind-whipped snow to New England on Sunday, threatening white-out conditions in coastal areas and forcing people to contend with a fourth winter onslaught in less than a month. (AP Photo/Steven Senne)