Thursday, August 20, 2015

The Climate Change ‘Bully’ in California’s Drought

The South Complex Fire near Hyampom, Calif., which has consumed an estimated 21,629 acres since starting on July 30. (Credit: U.S. Department of Agriculture/flickr) Click to Enlarge.
There’s a drought in California.  Perhaps you’ve heard a few things about it.

Like the fact that it’s cost the state $2.7 billion in losses, helped burn up roughly 118,000 acres of forest this year to date and inspired Los Angeles to release a 96 million-strong armada of shade balls into reservoirs (though it was apparently a PR stunt).  Oh, and the state is also missing a year’s worth of rain.

One question that’s lingered as long as the drought itself is just how much, if any, of the drought is due to climate change.  New research has an answer:  up to 27 percent.  It also has another important number:  climate change has made the odds of severe droughts like this one twice as likely.

The sobering numbers come from researchers at the Lamont-Doherty Earth Observatory, NASA and University of Idaho who analyzed temperature, precipitation, wind speed and other data to tease out the role climate change has played in the drought.

It’s the latest in a string of studies that have examined this big question.  The general consensus is that heat has played a role in exacerbating the drought and that at least some of that heat is part of the larger pattern of global warming.  Last year was a punctuation mark with record-setting heat baking the Golden State to crispy golden brown.

The “ridiculously resilient ridge” — an atmospheric feature that’s deflected storms every which way but over California since 2012 — also might have some climate change ties, though those are still somewhat murky.  But the specific role climate change has played in the drought hasn’t been truly teased out until this new study.

“This study is the first to parse out the relative contribution of anthropogenic warming versus natural climate variability,” Park Williams, a tree ring researcher at Lamont, said.  “From a method standpoint, it’s a big advancement.  It’s the first time I know of that data has been parsed apart this way for any drought on the planet.”

Williams led the latest round of research that uses temperature, precipitation, wind and other drought data to break the state up into grid of 23,955 boxes.  The data paint the sharpest picture yet of a state in severe drought.  Averaged across the state, the findings show that this hasn’t been California’s worst drought on record, but it is the worst drought on record in the places that matter the most to people.

Read more at The Climate Change ‘Bully’ in California’s Drought

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