Thursday, June 6, 2013

Climate and land use: Europe's floods raise questions

Seed Daily via AFP: Less than three months after being battered by snow and ice, central Europe now finds itself fighting floods -- and some scientists are pointing the finger at human interference with the climate system. Leading the charge is the Potsdam Institute for Climate Impact Research (PIK) near Berlin, which says a low-pressure system that dumped the rain was locked into place by a disturbance with a global wind pattern.

"We think it is linked to the current drought conditions in Russia as well," Stefan Rahmstorf, PIK's professor of ocean physics, told AFP. Normally, air moves around the mid-latitudes of the planet in the form of waves, oscillating irregularly between the tropics and the poles, Rahmstorf explained.

The main force behind this movement is the big temperature gap between the frigid Arctic and the warmer southerly latitudes. Like a pump, this differential helps to force air northward or southward. The problem, though, is that the Arctic is steadily warming -- last year, its summer sea ice hit its lowest extent on record -- so the temperature difference is declining.

As a result, according to the theory, the wave movement diminishes. At a certain point, pressure systems stay locked in place, causing a weather pattern that persists wretchedly. "This planetary wave resonance is not a local effect but spread around the whole (northern) hemisphere," said Rahmstorf in an email exchange....

June 4, 2013 in Germany on the Elster, shot by Dirk Bindmann, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

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