Skip to main content

ALERT: KPBS 89.5FM is undergoing scheduled upgrade work which may result in a temporary signal outage. Click here to listen on our radio stream.

LATEST UPDATES: Tracking COVID-19 | Vaccines | Racial Justice

Climate Change Could Soak Up California’s Fresh Mountain Water Runoff

Photo by buffdawgus/Flickr

The Sierra Nevadas deliver freshwater runoff that could dry up if temperatures continue rising.

A new study suggests rising temperatures could cut into California's water supply.

A new study suggests rising global temperatures could cut into California's water supply by altering high-altitude vegetation.

Water used to irrigate crops in the Central Valley often begins as runoff from the top of Sierra Nevada mountains. It's so cold up there, vegetation can't take root. But with global temperatures rising, that could change.

"Rain or snow comes in, and the vegetation — the forrest — sort of gets the first crack at it," said UC Irvine's Michael Goulden, a co-author of the new study. "And if it uses that water, it never makes it into the river."

New plants creeping to higher altitudes could sponge up more water before it reaches Californians below. That's the prediction laid out in a new study co-authored by Goulden.

"The mechanism we've identified is so simple," Goulden said. He and his colleagues looked at current relationships between elevation and climate, and teased out how that influenced the water cycle.

"We just combined those two things together and used that to directly project what the patterns of evapotranspiration would look like in 2100," Goulden said.

Goulden and his colleagues predict that, in the worst case scenario, Sierra Nevada freshwater runoff could decline more than 25 percent by the century's end.

It's hard to tell exactly what role climate change has played in California's current drought. But Goulden says many climate change factors could affect California's water supply in years to come.


San Diego News Now podcast branding

San Diego news; when you want it, where you want it. Get local stories on politics, education, health, environment, the border and more. New episodes are ready weekday mornings. Hosted by Anica Colbert and produced by KPBS, San Diego and the Imperial County's NPR and PBS station.

  • Need help keeping up with the news that matters most? Get the day's top news — ranging from local to international — straight to your inbox each weekday morning.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Curious San Diego banner

Want more KPBS news?
Find us on Twitter and Facebook, or sign up for our newsletters.

To view PDF documents, Download Acrobat Reader.