Paired oxygen isotope records reveal modern North American atmospheric dynamics during the Holocene

• Examines the past and the future of the jet stream using lake-sediment cores and climate models
• Finds that the jet stream's pattern shifted about 4,000 years ago into a "positive" or curvy phase—the same dynamic responsible for the ongoing hot/cold divide in America
• States the fact that the planet's poles are warming faster than the equator could enhance the pattern so there will be more frequent or more severe winter weather extremes or both

"In [the positive phase], the jet stream is very sinuous. As it comes in from Hawaii and the Pacific, it tends to rocket up past British Columbia to the Yukon and Alaska, and then it plunges down over the Canadian plains and into the eastern United States. The main effect in terms of weather is that we tend to have cold winter weather throughout most of the eastern U.S. You have a freight car of arctic air that pushes down there." 

When the jet stream is curvy, “the West tends to have mild, relatively warm winters, and Pacific storms tend to occur farther north. So in Northern California, the Pacific Northwest and parts of western interior, it tends to be relatively dry, but tends to be quite wet and unusually warm in northwest Canada and Alaska."

~ Co-author Gabriel J. Bowen