Just when weather weary Americans thought they'd found a reprieve, the latest forecasts suggest that the polar vortex will, again, descent into the heart of the country next week, bringing with it staggering cold. If so, it will be just the latest weather extreme in a winter that has seen so many of them. California has been extremely dry, while the flood-afflicted UK has been extremely wet. Alaska has been extremely hot (as has Sochi), while the snow-pummeled US East Coast has been extremely cold. They're all different, and yet on a deeper level, perhaps, they're all the same. This weather now serves as the backdrop—and perhaps, as the inspiration—for an increasingly epic debate within the field of climate research. You see, one climate researcher, Jennifer Francis of Rutgers University, has advanced an influential theory to explain winters like this. The hypothesis is that by rapidly melting the Arctic, global warming is slowing down the fast-moving river of air far above us known as the jet stream—in turn causing weather patterns to get stuck in place for longer, and leading to more extremes of the sort that we've all been experiencing. On the other hand, in a letter to the journal Science last week, five leading climate scientists—mainstream researchers who accept a number of other ideas about how global warming is changing the weather, from worsening heat waves to driving heavier rainfall—strongly contested Francis's jet stream claim, calling it "interesting" but contending that "alternative observational analyses and simulations have not confirmed the hypothesis." One of the authors was the highly influential climate researcher Kevin Trenberth of the National Center for Atmospheric Research, who we welcomed on the show this week alongside Francis to debate the matter. This episode also features a discussion about Indre's new 24 lecture course "12 Essential Scientific Concepts," which was just released by The Teaching Company as part of the "Great Courses" series. iTunes: itunes.apple.com/us/podcast/inquiring-minds/id711675943 RSS: feeds.feedburner.com/inquiring-minds Stitcher: stitcher.com/podcast/inquiring-minds

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