Sunday, September 6, 2009

Climate change boosts ultraviolet risk for high latitudes

Marlowe Hood and Richard Ingham in Agence France-Presse: Climate change will disrupt Earth's precious ozone layer, boosting ultraviolet (UV) radiation in the deep southern hemisphere and reducing UV in far northern latitudes, a study warned on Sunday. By century's end, UV levels in Antarctica could rise by up to 20 percent at seasonal peaks while average exposure in northern Scandinavia, Siberia and northern Canada could fall by almost a tenth.

The shift could have worrying impacts on human health, as high exposure to UV is linked to cancer, cataracts and crop damage just as low exposure causes vitamin D insufficiency. "Our study is showing that there is a new threat to the ozone layer, and this is climate change, which will either increase or decrease UV depending on the region," said atmospheric physicist Michaela Hegglin of Canada's University of Toronto.

"And while too much UV exposure is known to be a bad thing, too little UV exposure can also have detrimental effects, though these are much less explored."

…Hegglin and co-author Theodore Shepherd put together a computer model simulating the consequences of warmer surface temperatures on an atmospheric pump called the Brewer-Dobson circulation, which drives ozone around the world. Under it, air is moved upwards from the tropics -- where most ozone is produced -- and then shifts polewards before descending to the lower part of the stratosphere. There it lingers for a long time before eventually entering the troposphere, the lower part of the atmosphere that includes ground level….

An Antarctic view by Viajeropolar2008, Wikimedia Commons, under the terms of the GNU Free Documentation License, Version 1.2

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