'Crazy' climate re-engineering could reduce vital rains, study says

http://www.nbcnews.com/science/crazy-climate-re-engineering-could-reduce-vital-rains-study-says-8C11511636

John Roach NBC News
Nov. 1, 2013

If global warming gases build up so much that record-setting rains, droughts and coastal floods routinely bankrupt businesses and cities, the world's economic and political powers may decide to aggressively re-engineer the global climate. One option is to fill the atmosphere with enough sunlight-reflecting particles to restore surface temperatures to pre-industrial levels. If they do, would all be cool?

Absolutely not, according to a new study that asked the question to 12 models forced to simulate the global climate with four times more carbon dioxide in the atmosphere than existed in 1850, the start of the industrial revolution. Under such conditions, reflecting sunlight in order to lower temperatures to pre-industrial levels would cause monsoonal rains to drop 5 to 7 percent below pre-industrial levels.

Most previous modeling studies designed to ask a similar question about geoengineering have returned a similar answer: Blocking sunlight in a bid to cool a planet wrapped in a blanket of heat-trapping gases can have the undesired consequence of a reduction in monsoonal rains that much of the world relies on to grow food.

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