California has seen unprecedented drought over the last several years and one of the questions often asked is whether climate change is playing a role. Answers have varied—yes, no, maybe—with most scientists erring on the side of caution. Recently, though, the science has pointed toward yes.
The apparent cause of the drought—the high-pressure ridge in the Pacific west of California—is more likely to form in the presence of high greenhouse gas concentrations, according to research from Stanford University climate scientists and colleagues. The researchers used a combination of computer simulations and statistical techniques to reach the conclusion.
“Our research finds that extreme atmospheric high pressure in this region—which is strongly linked to unusually low precipitation in California—is much more likely to occur today than prior to the emission of greenhouse gases that began during the Industrial Revolution in the 1800s,” Stanford climate scientist Noah Diffenbaugh stated in a news release.
The high-pressure area, which has been dubbed the “ridiculously resilient ridge,” diverts winds from the jet stream to the north, causing Pacific storms to bypass California, Oregon, and Washington.
“Winds respond to the spatial distribution of atmospheric pressure,” said Daniel Swain, lead author of a paper published about the findings. "We have seen this amazingly persistent region of high pressure over the northeastern Pacific for many months, which has substantially altered atmospheric flow and kept California largely dry.”
The drought is also causing the western United States to “rise up like an uncoiled spring,” according to a study by scientists at the Scripps Institution of Oceanography. Scripps researchers Adrian Borsa, Duncan Agnew, and Dan Cayan found that the water shortage is causing an “uplift” effect up to half an inch or more in California's mountains and an average 0.15 of an inch across the West. Using GPS data, they estimated the water deficit at nearly 62 trillion gallons of water— the equivalent to a six-inch layer of water spread out over the entire western United States, according to a news release.
But a report in the Los Angeles Times offers the mildly optimistic news that even a prolonged seven decades of mega-drought would not turn California in a “giant, abandoned dust bowl.”
There have been droughts that prolonged in the past, and will certainly occur again. If it did, there’d be a substantial decrease in irrigated farmland, urban lawns would disappear (as would some salmon runs), and sewage and wastewater would be cleaned up and reused, according to a 2010 study outlined in the article.
“The weather record that we tend to depend on in California for allocating water … is based on about 150 years of really quite wet conditions when you look back at, say, the last 8,000 years or so," Cal State East Bay paleoclimatologist Scott Stine told the Times.
Under the extended drought scenario, cities largely did okay with the exception of higher water costs, UC Davis Center for Watershed Sciences director Jay Lund, who conducted the study, told the paper.
“They did more water conservation and wastewater reuse, a little ocean desalination, and purchased some water from farms," he said, referring to the study’s scenarios. “So the predominant part of the population and economy felt the drought, but was not devastated by it.”
“[Mega-drought] doesn't mean no water," Peter Gleick, president of the Pacific Institute told the paper. “It will mean using what we get more effectively.”