As Roger Ebert reminds us, Kevin Costner’s disaster-of-a-flick Waterworld opens “with the trademark Universal globe spinning in space, and then we see the polar ice cap melting while a deep voice (not James Earl Jones for a change) sets the story in “the future,” when all of the Earth is covered in water. Cut to Mariner (Kevin Costner), aboard his trimaran, a sailing vessel that looks made out of spare parts from Mad Max . . . peeing into a bottle, pouring the fluid into a home-made chemistry set, cranking a handle to process it, and then drinking it. Then he gargles, and spits on his little lime tree, so we know how he gets fresh water and vitamin C.”

Well, thank you Mr. Costner for preparing us for the future as envisioned by the California Department of Water Resources:

As global warming continues and California’s mountain snowpack decreases, the state can expect to see a drastic drop in its drinking and farm water supplies, as well as more frequent winter flooding. These are among the findings in a report released Monday by the state Department of Water Resources. The report was commissioned in response to Gov. Arnold Schwarzenegger’s order last year for state agencies to begin preparing for an altered climate. The result, a 338-page study, offers the most detailed look yet at how climate change could affect California water supplies.

Under each of four climate-change scenarios examined in the report, warmer temperatures raise the snow level in California mountains, producing a smaller snowpack and more winter runoff. This means more floodwaters to manage in winter, followed by less snowmelt to bank in reservoirs for drinking water, summer lawns and crop irrigation. The average difference by 2050, according to the report, would be a snowpack statewide that holds 5 million acre-feet less water. That’s more than the total capacity of Lake Shasta, the state’s largest reservoir.

Average deliveries to cities and farms from state and federal water systems could shrink by more than 10 percent, according to the report.

Full article here.