Californian snow at 500-year low

2015-09-14 18:04
Ed Victoria of Los Angeles sits under an umbrella as he fishes for tilapia along the receding banks of the Salton Sea near Bombay Beach, Calif. (Gregory Bull, AP)

Ed Victoria of Los Angeles sits under an umbrella as he fishes for tilapia along the receding banks of the Salton Sea near Bombay Beach, Calif. (Gregory Bull, AP)

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

Paris - Snow cover in the Sierra Nevada mountain range, a water lifeline for California's cities and agriculture, has hit its lowest level in 500 years, a study said on Monday.

Measured on April 1, the natural, frozen reservoir was barely five percent of the 1950-2000 average, threatening tens of millions of Californians and the state's $50bn agriculture sector with chronic water shortages, its authors warned.

And things were set to get worse, they wrote in the journal Nature Climate Change.

"We should be prepared for this type of snow drought to occur much more frequently because of rising temperatures," lead author Valerie Trouet, a professor at the University of Arizona, said in a statement.

"Anthropogenic" - or man-made - global warming "is making the drought more severe," she added.

The "snowpack" of Sierra Nevada, central California's 650km spine, provides more than 60% of the state's distributed water supply, including all or part of the drinking water for 23 million people.

Greater Los Angeles and the San Francisco Bay Area are among the zones affected.

On April 1 - when the snowpack is generally at its maximum - California Governor Jerry Brown declared the state's first-ever mandatory water restrictions. He made the announcement while standing on dry ground that a few years ago would have been covered by a man-high snow blanket.

Extremely low winter rainfall combined with record high temperatures during the first three months of 2015 are to blame, said the study.

Scientists had already established that this year's snowpack was the smallest since annual measurements began in the 1930s, but the new research goes even further back in time.

Tree rings

The team measured the rings of some 1 500 ancient blue oaks in the Central Valley - which runs parallel with the Sierra Nevada - for a record of annual rainfall in winter, when California receives 80 percent of its precipitation.

Given that the same storms which water the oaks also dump snow on the mountains, tree-ring width is a good proxy for what the snowpack would have been in any given year.

The team then compared their tree-ring data with a reconstruction of winter temperatures for the period 1500-1980, to create a year-by-year snowpack profile.

"This is not just unprecedented over 80 years - it's unprecedented over 500 years," Trouet said of the findings.

California is in the grips of a four-year drought, and ravaged by wildfires that have destroyed more than 40 470ha, hundreds of homes and businesses, authorities say.

According to the US Geological Survey, more than 120 of the state's reservoirs are less than a fifth full, and 190 under half.

This also threatens California's hydroelectric power sector - a key source of renewable energy.

Scientists warn that climate change will likely boost the frequency and intensity of droughts.

Read more on:    us  |  weather  |  water

Join the conversation! encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions.

Inside News24


Book flights

Compare, Book, Fly

Traffic Alerts
There are new stories on the homepage. Click here to see them.


Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.

Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire network.


Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.

Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.