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Monday, February 17, 2014

Research Points To Jet Stream In Brutal Winter

Across the U.S., it has been a brutal winter, from the drought in the West to ice and snow in the South and frigid temperatures across the states.

New research presented at the American Association Advancement of Science in Chicago is pointing to changes in the jet stream as the reason for these lingering weather conditions.

Here & Now’s Meghna Chakrabarti speaks with Jennifer Francis, research professor at Rutgers’ Institute of Marine and Coastal Sciences, about her findings.

Guest

  • Jennifer Francis, research professor at Rutgers’ Institute of Marine and Coastal Sciences

Transcript

MEGHNA CHAKRABARTI, HOST:

Well, in Indonesia this weekend, Secretary of State John Kerry called on all the nations of the world to respond to climate change. Meanwhile, here in the U.S., some scientists say that climate change is one of the reasons behind the brutal winter weather that's hit much of the country this season. An expert panel at the American Association for the Advancement of Science in Chicago points specifically to significant climate-driven changes to the jet stream.

Jennifer Francis was on that panel. Welcome.

JENNIFER FRANCIS: Thank you very much. I'm glad to be here.

CHAKRABARTI: So first of all, just about everybody who watches the nightly news sees pictures of the jet stream on evening weather reports all the time. Explain to us what the jet stream has to do with this recent extreme weather we've been seeing across so much of the country.

FRANCIS: Right, well, the jet stream really is the key part of the climate system that determines our weather. It creates it, and it steers it. And it's this fast-moving river of air high over our heads where the jets fly that goes from west to east around the Northern Hemisphere, and it takes kind of a wavy path as it does so.

CHAKRABARTI: And so, Jennifer, tell us about why the recent weather pattern we've been seeing is so different. I understand it has something to do with how cold it is in the Arctic, versus lower latitudes.

FRANCIS: Right. So the reason we believe things are starting to change is because the Arctic is warming much faster than the areas farther south. So that means this difference in temperature between the Arctic and areas farther south is getting smaller. And that means the force that drives the jet stream is getting weaker.

And when the jet stream winds that blow from west to east get weaker, the jet stream tends to take a wavier path as it travels around the Northern Hemisphere. And when those waves that are in the jet stream naturally get bigger, they tend to move more slowly from west to east. That means that the weather associated with those waves in the jet stream tends to also move more slowly from west to east.

So, for somebody down on the Earth, it feels like the weather pattern that you're in is lasting longer. This winter, that's exactly what's been happening, is we've had this extremely wavy jet stream pattern. There's been a big northward swing up into Alaska, bringing a lot of warm air up into Alaska. They've had an extremely warm winter there.

And then it's dipped southward over California, blocking the usual storms from coming into California, contributing to the drought they're having there. And then it continues southward in a big southward dip, which we call a trough, over the eastern two-thirds of the country. And this has allowed the Arctic air to spill down over much of the eastern half of the U.S., causing this cold spell that we've been having for the last couple of months.

And so, as I said, when the jet stream gets into one of these very wavy patterns like this, it tends to sometimes even get stuck, and that's what we've seen this winter, is this very wavy pattern has been in place, really, since the beginning of December.

CHAKRABARTI: My question for you is you mentioned that the problem seems to be due to the fact that the Arctic is warming so much faster than normal. Is that because of climate change?

FRANCIS: Well yes, the Arctic is warming faster than normal because of the increasing greenhouse gases in the atmosphere. And this is something that we've known about for a very long time. We've been expecting to see the Arctic start to warm up really rapidly, compared to everywhere else on Earth.

CHAKRABARTI: Jennifer, I know you've been studying this for a long period of time. And it seems that we're now in a new age where the effects on climate change are really everywhere. They're in our own backyards, and they last a long time. I mean, what's your greatest concern from the research that you presented this weekend?

FRANCIS: There's two sides to this, I think. I mean, the research that we're doing suggests that we're going to see more persistent weather patterns. And this leads to some types of extreme weather events, things like, you know, the prolonged storminess they're having the U.K., and the long cold spell we've had in much of the U.S.

But other factors related to climate change are going to have other impacts on extreme weather, and we're already starting to see those, things like stronger heat waves and droughts. Of course, that's been a big story in our country for the last few years. And so people are starting to realize that climate change is not going to be this slow warming that we don't have to worry about till, you know, our grandchildren come along.

This is something that's happening now, and it's affecting people personally.

CHAKRABARTI: Well, Jennifer Francis is research professor at Rutgers Institute of Marine and Coastal Sciences. She was on the panel that presented new findings about changing jet stream patterns and extreme weather we've been seeing this winter. She presented that to the American Association for the Advancement of Science this weekend. Jennifer, thank you so much.

FRANCIS: You're very welcome. Transcript provided by NPR, Copyright NPR.


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