California drought 'not caused by global warming', official study finds...
A dried-up irrigation ditch is a sign of the drought that has gripped California for three years, although climate change is not to blame, says the National Oceanic and Atmospheric Administration. Photograph: Jae C Hong/AP
Don’t blame man-made global warming for the devastating California drought, a new federal report says.
A report issued on Monday by the National Oceanic and Atmospheric Administration said natural variations – mostly a La Niña weather oscillation – were the primary drivers behind the drought that has now stretched to three years.
The study’s lead author, Richard Seager of Columbia University, said the paper has not yet been published in a peer-reviewed scientific journal. --
He and NOAA’s Martin Hoerling said 160 runs of computer models show heat-trapping gases should slightly increase winter rain in parts of California, not decrease.
Hoerling said La Niña, which is the cooler flip side of the warming of the central Pacific ocean, can only be blamed for about one-third of the drought. The rest of the causes can be from just random variation, he said.
Peer-reviewed studies are divided on whether the drought can be blamed on climate change. Others published earlier this year point more directly to changes in pressure of the Pacific that blocked rain from coming into California, but Hoerling and Seager dismissed them as not adequate.
http://www.theguardian.com/us-news/2014/dec/08/california-drought-not-caused-by-global-warming-official-study-finds
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