Link to 338 page report, baydeltaoffice.water.ca.gov
An excerpt from the story.Climate report sees a thirsty future
Global warming will shrink state's water supplies but trigger floods, study warns.
By Matt Weiser -- Bee Staff Writer Published 12:01 am PDT Tuesday, July 11, 2006
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.
"A 10 percent decrease in deliveries is significant to our water users," said Kathy Kelly, chief of DWR's Bay-Delta branch, which oversaw the report. "I think it says we need to be paying attention and we need to start incorporating this into our strategic plans for managing California's water resources."
Climate scientists now broadly agree the climate is slowly warming, and that this is caused, at least in part, by humans. As fossil fuels are burned to heat homes and propel vehicles, carbon dioxide is released into the air, boosting the atmosphere's ability to trap heat from the sun.
Along with the reduction of the mountain snowpack, the DWR report found that global warming could pose a grave threat to the health of the Sacramento-San Joaquin Delta.
The Delta is both a vital habitat for endangered fish and birds and a key water conveyor for humans, ferrying fresh water from Northern California reservoirs to farms and cities in the south. It serves 23 million Californians and 5 million acres of farmland that underpin the world's fifth-largest economy.
Climate scientists predict ocean levels will rise in coming decades as the warming atmosphere accelerates Arctic melting. A 1-foot sea level rise -- on the low side of most predictions -- would push more salty water into the Delta, contaminating the water supply. This could require water managers to release even more fresh water from reservoirs to keep the Delta water usable.
That same 1-foot sea level increase also likely would flood Sherman, Twitchell and Jersey islands in the western Delta during high tides and stormy conditions.
"The report clearly points out the reason this is a double-whammy type problem," said Chris Field, director of the Carnegie Institute's Department of Global Ecology at Stanford University.
"You not only lose the snowpack, but you also lose the ability to manage reservoirs for both flood control and irrigation."
Field co-authored a broader study of California climate change two years ago. He praised the DWR report for applying current research to ground-level problems.
"The kind of info DWR has assembled here is going to be really useful in helping the state position itself to take aggressive action on climate change," he said.
Others agree the time for action is now, though they disagree about how California should respond.
Steve Hall, executive director of the Association of California Water Agencies, said the state needs to start building more reservoirs and groundwater storage systems.
"We don't have all the answers, but we know enough now about the certainty and magnitude of climate change to begin to prepare in earnest," said Hall. "I don't want to be alarmist, but frankly I think it's difficult to overstate the threat."
Jonas Minton, a senior project manager with the Planning and Conservation League, noted that a separate state plan found that aggressive conservation and recycling could offset the 5 million acre-feet California may lose to a shrinking snowpack.
"This is not a total doom-and-gloom future for California," he said. "The state should be helping homeowners, businesses and farmers better conserve and recycle the water supplies we have available."
