It was raining in San Francisco on the damp December morning that three scientists gathered at the offices of Climate Nexus to hold a press conference about the drought. It had been raining regularly for more than a week, in fact, and Stanford University had just recorded its rainiest day ever on campus.
These three drought experts had gathered to swim upstream against all that rain and evaporate any false optimism it might be washing into California.
“I’m happy to be here and see some rain here in San Francisco,” said Jonathan Overpeck, who had flown in from Tucson, where he is a founding codirector of the Institute of the Environment at the University of Arizona. ”Of course everyone knows California’s drought has been for three years, rain so far has been helpful, there’s a snowpack in the Sierra Nevada’s that is about 50 percent of normal thanks to recent precipitation, but that hasn’t stopped the drought. The drought is still going to be the story at the end of the year, I think.
“To frame the drought we should be mentioning that much of the southwest and west has been in drought now for nearly 15 years, since 1999. This is important for California because a big part of that story is the Colorado River. The major storage, the biggest reservoirs in the United States are only half full now, and precipitation this winter has been lower than average there.”
The scientists had gathered in part because a recent study from NOAA has been interpreted to suggest the drought derives from the natural variability of the climate. But these three scientists say that interpretation derives from NOAA’s focus on only one aspect of the drought—mean rainfall. When you look at the drought as an extreme event, they said, and when you look at its probability of recurring, and when you look at not only rainfall but also temperature and evaporation, there’s no doubt what’s behind the drought….moew