Wacky jet stream to blame for wild North American weather

A lot of wild weather has afflicted North America this year: deluges in Colorado and Alberta, a heatwave in Alaska, and bitter cold in Florida. But there’s a high-altitude link between each of these unusual events which itself might be tied to climate change: erratic behavior by the polar jet stream.

The normally direct polar jet stream has been swinging wildly this summer, dipping north and south like the line graph on a U.S. jobs report. At times it splits in two.

Usually at this time of year the jet stream is a single band around the Northern Hemisphere, but in August what we’ve seen is a smaller jet stream over the Arctic Ocean, and another jet stream in the midlatitudes.”

There’s no scientific agreement right now on what role, if any, climate change is playing in the polar jet stream’s erratic behavior. But Francis points out that it is the product of vast temperature differences between the equator and the North Pole.

    

As the globe warms, the Arctic heats at a disproportionately fast rate, and that chips away at the temperature gradient. If that turns out to be what sent the jet stream into a weird spin cycle, then the Northern Hemisphere has a lot more extreme weather coming its way.

http://grist.org/news/wacky-jet-stream-to-blame-for-wild-north-american-weather/