Climate scientists now expect California to experience more rain in the coming decades, contrary to the predictions of previous climate models.
University of California, Riverside, 6 July 2017
“Most previous research emphasized uncertainty with regards to future precipitation levels in California, but the overall thought was California would become drier with continued climate change. We found the opposite, which is quite surprising.” –Robert Allen, University of California, Riverside
Normalized precipitation over Western North America (five-year mean) from 22 climate models used to formulate the 2013 IPCC report, as summarized by Schwalm et al., 2012, Reduction in carbon uptake during turn of the century drought in western North America.
Most scientists agree that California, like most places, will get warmer through the end of the century. And until now, most agreed California would get drier. New research out of the University of California, Riverside, however, suggests otherwise.
The new models predict the state will enjoy a 12 percent increase in precipitation totals through 2100.
Both central and northern California will get wetter, according to the models, while Southern California will experience slightly less precipitation through the end of the century. Most of the increase in precipitation will be during the winter months.
“Most previous research emphasized uncertainty with regards to future precipitation levels in California, but the overall thought was California would become drier with continued climate change,” Robert Allen, an associate professor at UC Riverside, said in a news release. “We found the opposite, which is quite surprising.”
Weather variability makes it difficult to project how climate change will affect rain and snow totals. Predicting future precipitation totals in California is further complicated by the fact that the northern half of the state is expected to get wetter while the southern half is predicted to get drier.
But predictive climate and weather models are growing more sophisticated, allowing scientists to quiet the noise of yearly variability and focus on longterm patterns.
The new research — detailed in the journal Nature Communications — suggest increasing surface temperatures in the tropical eastern Pacific Ocean, lying to the 2,500 miles east, will encourage a local trade wind delivering a larger number of storm systems to the California coast.
“Essentially, this mechanism is similar to what we in California expect during an El Nino year,” Allen said. “Ultimately, what I am arguing is El Nino-like years are going to become more the norm in California.”
In other words, California’s future is likely to look more like the past two years, during which the state enjoyed record rainfall totals.