Harsh winter weather in eastern US could be due to warmer Arctic
mardi 13 mars 2018, 19:47 , par Ars Technica
Enlarge / Temperatures at the start of 2018—a familiar pattern as of late. (credit: NASA Earth Observatory)
Without some historical context, it’s easy to over-interpret an unusual weather event, especially when it's fresh in your mind. At this time of year in the US, that means cold snaps or unseasonably warm weather—and the storms that accompany them. Are they tied in with our changing climate?
There’s a legitimately controversial proposal that they are. The idea that warming in the Arctic (and shrinking sea ice coverage) has been making northern mid-latitude winters “weirder” has drawn a lot of attention in recent years. But does it explain the weather you complained about last week?
The idea suggests that the weirdness is driven by the fact that the Arctic is warming faster than any other region, which slightly decreases the temperature difference from equator to pole. A number of researchers think this can cause the jet stream (which separates frigid polar air from warmer midlatitude air) to get more wiggly—allowing cold air to spill southward more frequently. On the opposite side of those wiggles, warm air will get pulled north to normally frigid regions.
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sam. 15 déc. - 06:48 CET