The Sierra Nevada could lose a third of its snow by 2050 (Image: Robert Harding World Imagery/Alamy)

The Golden State is baking. After months of drought in California the long-term forecast is… more drought.

Rising global temperatures will turn much of the snow that currently replenishes the state’s reservoirs to rain, according to modelling studies by Dan Cayan at the Scripps Institution of Oceanography in San Diego. Unlike snow, which melts each spring and recharges California’s reservoirs, rain evaporates and soaks into the ground – it dwindles away, he says.

Cayan says the Sierra Nevada snowpack could be a third smaller in 2050 than it has been in recent years, and two-thirds smaller by 2100. The snowpack isn’t the only source of fresh water in California, but Cayan says it would be “more of a challenge” to manage water as rainfall rather than snow. He presented his findings at the Bay-Delta Science Conference in Sacramento last week.


Cayan’s findings emerged as California’s Department of Water Resources (DWR) launched its latest strategic plan to manage the state’s water. The future is one of never-ending restraint in water use. “The goals of the plan are to make conservation a way of life,” says a department statement.

The main focus of the plan is to connect all California’s currently fragmented water sources so they’re easier to manage, and to rebuild much of its water supply and flood protection infrastructure.

It will cost $200 billion over the next decade just to maintain current levels of service, and $500 billion over coming decades to improve it, the plan says. On 4 November, California governor Jerry Brown launched a scheme to issue “water bonds” through Proposition 1 – a measure which, if approved by voters, authorises the state to spend $7.5 billion on water system improvements.

Cayan says the DWR has paid close attention to all climate change projections issued by the Intergovernmental Panel on Climate Change, and the latest plan includes a climate change component. “I believe California has been quite progressive, and is on the right track,” he says. “But I think it’s fair to say that water management will have to adjust as the climate warms in future decades.”