2015-08-20. Climate Change Intensifies California Drought, Scientists Say.

posted Aug 20, 2015, 2:33 PM by Alan Gould
By Justin Gillis, The New York Times. For GSS Climate Change chapter 8. Excerpt: Global warming caused by human emissions has most likely intensified the drought in California by roughly 15 to 20 percent, scientists said Thursday, warning that future dry spells in the state are almost certain to be worse than this one as the world continues to heat up. Even though the findings suggest that the drought is primarily a consequence of natural climate variability, the scientists added that the likelihood of any drought becoming acute is rising because of climate change. The odds of California suffering droughts at the far end of the scale, like the current one that began in 2012, have roughly doubled over the past century, they said. “This would be a drought no matter what,” said A. Park Williams, a climate scientist at Columbia University and the lead author of a paper published by the journal Geophysical Research Letters. “It would be a fairly bad drought no matter what. But it’s definitely made worse by global warming.”  ...Rising temperatures dry the soil faster and cause more rapid evaporation from streams and reservoirs, so they did not need any research to tell them that the drought was probably worse because of the warming trend over the past century — the same is true for pretty much any drought in the world. The challenge has been to quantify how worse the California drought has become because of human emissions.... http://www.nytimes.com/2015/08/21/science/climate-change-intensifies-california-drought-scientists-say.html