Weather Whiplash: As Polar Vortex Brings Deep Freeze, Is Extreme Weather Linked to Climate Change?
Jeff Masters, director of meteorology at the Weather Underground.
Dr. Jeff Masters’ WunderBlog
AMY GOODMAN: So, tell us what an Arctic vortex is.
JEFF MASTERS: Sure. It’s a situation you see every winter over the Arctic. I mean, you’ve got 24-hour darkness up there, and the cold air tends to build and build and build because of the lack of sunlight. And when you get all that cold air up there, it tends to drive stronger winds. And those winds blow counterclockwise around the pole in a vortex, and those winds tend to isolate that cold air from the rest of the world. And so, that cold air can stay cold, and when that happens to slosh over where we are, boy, we sure notice it.
AMY GOODMAN: How can the Earth getting hotter relate to such cold weather?
JEFF MASTERS: Yeah, this is a one-in-20-year type of cold weather event, which you expect to see grow less common as the planet heats up. I mean, the planet has heated up about a degree and a half Fahrenheit over the last 130 years, and you expect these one-in-20-year events to maybe occur one-in-30 years. But they’re still going to happen.
OK, now counterbalancing the fact that we would expect to see these events grow less common due to the fact the planet is warming up is, well, maybe, if we alter circulation patterns in such a way where the polar vortex now will slip southwards more often, then you could counterbalance that. And there is some evidence over the last few years that the jet stream has been doing something we haven’t seen before, at least not as often. Normally those winds blow straight west to east, with a little bit of waviness to it, but now we’re seeing more extreme excursions in the jet stream, where you get these big bulges, these high-pressure ridges on one side, and then low pressure dipping far to the south—very unusual to see these sort of contortions like we’ve had in recent years. And there is evidence that possibly Arctic sea ice loss could cause that sort of jet stream behavior.
AMY GOODMAN: Can you talk about what the drunk jet stream is?
JEFF MASTERS: Yeah. Well, normally the jet blows, like I said, straight west to east, but when the winds slow down in the jet stream, now they tend to wander around a little more. They’re not constrained to flow in this kind of tight, narrow ribbon so much. Now they can do kind of these big meandering loops. And when you reduce the temperature difference between the Equator and the poles, you tend to slow down the winds of the jet stream, and you tend to allow this sort of meandering behavior. And this difference in temperature between the Equators and the poles has been growing less and less in recent years because we’ve been losing so much Arctic sea ice. That allows the sun to shine more intensely up there, because now you’re exposing open water, which is dark, absorbs more sunlight, heats up the area, melts more ice, in kind of a vicious cycle, and increases the warmth even more. So, all this kind of makes sense that it could be the fact that warming in the Arctic is altering jet stream behavior.
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