Extreme weatherCalifornia suffering: Severe climate future for the state
California is headed for a future of precipitation extremes. Researchers say that the state will experience a much greater number of extremely wet and extremely dry weather seasons — especially wet — by the end of the century. The authors also predict that there will be a major increase in the likelihood of severe flooding events, and that there will be many more quick changes from one weather extreme to the other.
California is headed for a future of precipitation extremes.
Research by UCLA climate scientists, published in Nature Climate Change, projects that the state will experience a much greater number of extremely wet and extremely dry weather seasons — especially wet — by the end of the century. The authors also predict that there will be a major increase in the likelihood of severe flooding events, and that there will be many more quick changes from one weather extreme to the other.
Those who manage California’s water supply and protect residents from wildfires, floods and other natural disasters should be planning for those changes, said lead author Daniel Swain, a climate scientist at UCLA’s Institute of the Environment and Sustainabilityand The Nature Conservancy. Millions of lives, wildlife and the health of a multitrillion-dollar economy depend on it.
Although the differences won’t be noticeable to people who merely watch statistics like average annual rainfall — because the dry and wet periods will largely cancel each other out — they will have a major effect on the lives of Californians.
“These are actually huge changes occurring; they’re just on opposite ends of the spectrum,” Swain said. “If you only look for shifts in average precipitation, you’re missing all of the important changes in the character of precipitation.”
UCLA says that Swain and his fellow researchers, including professors David Neelin and Alex Hall of UCLA’s department of atmospheric and oceanic sciences, also found that California’s wet weather may become even more concentrated in winter months than it already is, while storms in the spring and fall become less likely and less frequent.
The study predicts that the changes will be powered by two common features: a warming atmosphere and warming oceans.
“In a warmer climate, there is more water vapor in the atmosphere,” Neelin said. “When a storm gets going, air converges at low levels carrying more water vapor with it. With more vapor to dump out, the result is more rainfall.”
The “Other Big One”
The UCLA study also found that over the next 40 years, the state will be 300 to 400 percent more likely to have a prolonged storm sequence as severe as the one that caused a now-legendary California flood more than 150 years ago.
