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"It's an intriguing theory - that recently has gotten legs: the melting Arctic - spurred by global warming - is causing the weather's steering flow, the jet stream, to become more extreme. This extreme jet stream - rather than zipping around the world in a straight circle (right below) - is more frequently meandering off course (left below) and getting stuck in place, sending bitter, prolonged blasts of cold southward and conversely, see-sawing strong heat domes northward. It's a fascinating paradox: global warming as the culprit for bone-chilling cold.
But more and more scientists are expressing reservations about this hypothesis, first proposed by Rutgers climate scientist Jennifer Francis and collaborators.
"It's an interesting idea, but alternative observational analyses and simulations with climate models have not confirmed the hypothesis, and we do not view the theoretical arguments underlying it as compelling," write five preeminent climate scientists (John Wallace, Isaac Held, David Thompson, Kevin Trenberth, and John Walsh) in a recent letter published in Science Magazine.
Elizabeth Barnes, an atmospheric scientists from Colorado State University, after an attempt to dismantle Francis' theory last summer, published a second challenge in January.
"...the link between recent Arctic warming and increased Northern Hemisphere blocking is currently not supported by observations," Barnes' study concludes."
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8 February 2014: Car-sized boulder breaks off mountain in French Alps, smashes into first carriage and leaves train dangling over steep embankment - 2 dead, 10 injured