California’s Drought Intensified by Climate Change

August 21, 2015

Above item from a BBC production shows that scientists have been concerned about climate enhanced drought impacts in California and other areas for several decades,  in particular the social and economic impacts of these kinds of events.

Here’s an update on a few things we know about the current California drought. As senior scientists have been telling me for years, climate warming may or may not cause more droughts, but for those that do occur, they can come on stronger, be more intense, and perhaps last longer, then they other wise would.  New research confirms this is the case in the ongoing California situation.

Experts have told me that the new research looks at whether a warmer climate in itself has intensified the drought, but not as to whether a warmer climate has caused unusual atmospheric circulation patterns, such as the “ridiculously resilient ridge” that has been so persistent in diverting moisture from the US West Coast.

NYTimes:

Global warming caused by human emissions has most likely intensified the drought in California by 15 to 20 percent, scientists said on 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 the Lamont-Doherty Earth Observatory of 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.”

and, Oh, by the way..

The National Oceanic and Atmospheric Administration also reported Thursday that global temperatures in July had been the hottest for any month since record-keeping began in 1880, and that the first seven months of 2015 had also been the hottest such period ever. Heat waves on several continents this summer have killed thousands of people.

Here, Kevin Trenberth sums up the effect of a warming climate on droughts.

Below, several interviews shed more light on the evolving crisis.

Noah Diffenbaugh of Stanford, on Drought and Atmospheric Circulation:

Recent studies indicate this drought may be the worst in at least 500 years.

Diffenbaugh and his Grad student Daniel Swain discuss the “ridiculous ridge”.

My video from Spring of 2014 discussed the origins of the drought with several experts from NASA and elsewhere.

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