Department of Water Resources
A daily compilation for DWR personnel of significant news articles and comment
April 2, 2009
1. Top Items–
Report outlines possible effects of warming on California
The
Warming to bring more flooding and fire, less rain to state
The Contra Costa Times
Outlook is for stress to state's water supply
The San Francisco Chronicle
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Report outlines possible effects of warming on California
The
By Bettina Boxall
A compilation of research papers suggests that climate change will mean the state will have less water, experience a loss of cropland and see soaring wildfire rates.
As
The document, which officials called the "the ultimate picture to date" of global warming's likely effect on California, consists of 37 research papers that examine an array of issues including water supply, air pollution and property losses.
Without actions to limit greenhouse gas emissions, "severe and costly climate impacts are possible and likely across
The draft Climate Action Team Report, an update of a 2006 assessment, concludes that some climate change effects could be more serious than previously thought.
By the final decades of the century, acreage burned across much of the state's northern forests could easily double and under some scenarios quadruple, said Anthony Westerling, an assistant professor of geography and environmental engineering at UC Merced.
The reason is simple: As the temperature rises, the fire season lengthens and woodlands get drier, burning more readily.
Moreover, if growth continues at the wild-land edge, more fire will mean mounting home losses -- as high as $14 billion a year by century's end.
"If you spread development all through the Sierra foothills over the next 50 years," Westerling said, "you will have a situation like the hills of Southern California or Oakland" -- where wildfire has destroyed thousands of homes at a time.
One bit of good news is that in Southern California, the
Researchers believe they have already seen a 30% drop in
One of the less certain areas of climate change modeling involves precipitation patterns. Some studies have suggested that
But Dan Cayan, a climate researcher at Scripps Institution of Oceanography at UC San Diego, said "the latest generation of simulations from global models are producing a drying over the Mediterranean and lower continental latitudes -- and
By mid-century, annual precipitation in
Cayan cautioned that "our tools to get at this are still pretty crude. These are only rough numbers."
The Sierra Nevada snowpack, which stores water and then slowly releases it to the river systems that feed the state's major reservoirs, will shrink by at least a quarter over the next four decades, previous studies have concluded.
Combined with drier and hotter conditions, that will create water shortages expected to fall most heavily on the state's agricultural sector in the
Urban areas should be able to make up for shortfalls by buying water from farms, which use most of the supplies in the state.
But that will drive up the cost of water, prompting farmers to fallow cropland and abandon irrigated pasture and less profitable crops such as cotton, alfalfa and rice.
UC Davis agricultural economics professor Richard Howitt estimates that the
Revenue losses will be less steep -- about 10% or $3 billion a year -- thanks to shifts to more profitable fruits, vegetables and nuts.
The three water studies included in the climate report "describe relatively modest impacts of climate change on the water sector," according to the document.
But in a news conference, Adams and UC Berkeley economics professor Michael Hanemann said those findings were based on a "rosy scenario" of average water conditions as well as the legal and physical ability to move massive amounts of water from one user to another.
Global warming is expected to increase weather swings, from years of flooding to severe drought.
"There are more bad years than before and the bad years are worse in terms of shortages," Hanemann said.
In other areas, hydropower production is expected to decline along with the snowpack, while statewide electricity use could shoot up 55% by the end of the century and ozone pollution will increase.#
http://www.latimes.com/news/local/la-me-climate2-2009apr02,0,1696993.story?track=rss
Warming to bring more flooding and fire, less rain to state
The Contra Costa Times – 4/01/09
By Mike Taugher
"Extreme events from heat waves, floods, droughts, wildfires and bad air quality are likely to become more frequent in the future and pose serious challenges to Californians," said the report, a synthesis of 37 scientific papers.
The report, the first update of a 2006 assessment on climate change in
Among the key findings:
· Air pollution may worsen, and heat waves will be more intense, longer and more frequent, aggravating asthma symptoms and increasing infectious diseases;
· Cranked up air conditioners could drive up electricity consumption by more than 50 percent by 2100, while the availability of hydropower will decrease;
· Property losses due to wildfires could increase to $2 billion a year by 2050 and $14 billion a year by 2100;
· Farmers' yields will decrease for most crops;
Doing nothing to slow greenhouse gas emissions and to adapt to what scientists now say is at least a measure of inevitable warming would cost the state hundreds of billions of dollars, state leaders said.
"Taking immediate action on climate change is essential to slow the projected rate of global warming," said Linda Adams, secretary of the state Environmental Protection Agency. "We also need to make smarter decisions in order to anticipate and adapt to the changes."
Scientists believe earlier studies that predicted up to a 2 foot rise in sea level were too conservative and that a more realistic figure is 4.5 feet by 2100.
And earlier studies were inconclusive on whether California will get more or less precipitation, agreeing until recently only that more of the state's total precipitation would fall as rain instead of snow.
But it now appears the southern part of
The northern Sierra Nevada could see a little more precipitation, but overall the state will be more parched — and that will put more pressure on already-stressed water supplies, said Dan Cayan, a climate researcher at the Scripps Institution of Oceanography at UC San Diego.
The report took two scenarios for greenhouse gas emissions — one in which emissions continue to increase in a "business as usual" fashion and another in which emissions decline by 2100 — to try to glean a realistic look into California's future.
Those scenarios would result in average temperature increases of 2.7 degrees to 10.5 degrees by 2100, and the 37 peer-reviewed studies looked into how that would affect California's coasts, water supply, health, fires, demand for electricity, agriculture and forestry industries, among other things.
It is probably the most intensive attempt yet to project climate change impacts in a particular region, but the work is heavily dependent on models that cannot be perfect.
"They're plausible, but they're not precise," said Cayan.
While much of the report strengthened the 2006 report's findings, there were a few new findings to raise new concern.
"We think that the possibility of sea level rise at a higher magnitude is greater," Cayan said. "There is more precision about the impacts of sea level rise in the Bay Area."
Rising seas threaten an estimated $100 billion in property statewide, two-thirds of which is in the Bay Area, the report found.
"The most prominent features subject to inundation in the North Bay are the wetlands surrounding San Pablo and Suisun bays; municipal and industrial areas along the Martinez-Pittsburg corridor; the Richmond-Pinole peninsula; and areas in eastern Marin," the report said.
"In the central and south bays, a ring of developed areas currently behind levees would be newly at risk as sea level rise is expected to greatly increase pressure on existing levees and increase the risk of breaching. Other areas, such as
The findings on how the state's water supply would be affected contained inconsistencies. While the thrust of the report was that less precipitation, a longer and drier summer and a severely diminished snowpack would pose severe problems, an economic analysis showed the impact would be relatively small as water is moved around the state and urban areas slake their thirst by buying water from farmers.
A UC Berkeley economist said that best-case scenario was unrealistic and that even if average years work out OK, there are likely to be more severe problems in dry ones.
"A big part of the story is not the average year," said Michael Hanemann.#
http://www.contracostatimes.com/news/ci_12047842?source=rss
Outlook is for stress to state's water supply
The state report released Wednesday found that "changing precipitation patterns will result in longer and drier droughts and decreased groundwater levels, coupled with a higher frequency and severity of extreme flooding events."
Researchers forecast that in some years, water levels in the state's mainstay reservoirs - Shasta, Oroville, Folsom and Trinity - could fall below outtake pipe levels, effectively shutting off the spigot.
Winter snowpack in the
What's more, snowpack is expected to peak and melt earlier. That means more precipitation will fall as rain - raising the potential for overwhelming the state's increasingly fragile plumbing system.
The ailing Sacramento-San Joaquin River Delta sits squarely in the crosshairs, not just for rising floodwaters but also for higher sea levels.
With California's population expected to swell to nearly 60 million in 41 years - mostly in cities and suburbs - one scenario in the report suggests that supplies would come from agriculture, the state's largest water user.
Wildlife and ecosystems, whose water interests already compete with urban and agriculture users, also could be affected.
If the climate becomes significantly drier and water supplies reach rock-bottom levels,
The study said state officials are working on broader conservation efforts, ecosystem improvement, regional water management plans and developing additional supplies through water recycling and seawater desalination.#
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/04/02/MNFT16R1D7.DTL
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