Scientists Seek to Predict Global Warming's Effects in California
1/31/2006 6:01:00 AM
San Jose Mercury News
Scientists say California's iconic landscapes -- from beaches to snow-capped mountains and fog-shrouded redwoods -- are in for dramatic changes as the world gets warmer.
Now, with a new generation of computer models, they're trying to pinpoint to within a few miles what those changes will be:
Less snow? More wildfires? Fewer native oaks in places such as Henry W. Coe State Park?
Scientists want to understand how warming will affect the state's people, its economy, and the thousands of species, from giant sequoias to Sonoma chipmunks, that live in the state -- and nowhere else.
"Is our water supply going to become more limited?" asked Edwin Maurer, a hydrologist at Santa Clara University. "Well, yes, especially in dry years."
Focus of research
The goal of the research is to limit the impact of such changes. The focus is on three areas:
The Sierra Nevada is the source of much of our water and vital for wildlife, recreation and the ski industry. As temperatures warm, the snowpack will shrink, and animals and plants will be forced higher into the mountains; eventually some will run out of room.
In the Central Valley, as explosive development replaces fertile cropland, it will trigger still more warming and pollution.
Along the coast, where millions of people live, work and play, the interaction of land and water gives rise to cooling fog. It also generates winds that ventilate the Central Valley, push pollutants around and influence weather.
California started the only state-sponsored climate research program three years ago and is spending about $5 million a year on it.
That focus intensified in June, when Gov. Arnold Schwarzenegger signed an executive order setting targets for reducing emissions of carbon dioxide and other greenhouse gases. It calls for shaving emissions to 2000 levels by 2010, to 1990 levels by 2020 and 80 percent below 1990 levels by 2050.
Climate team meets
The state's Climate Action Team has scheduled a hearing today in Los Angeles on the economic impacts of these targets. A draft plan for achieving the targets, while keeping California competitive and economically healthy, is under review and on the Web at
http://www.climatechange.ca.gov; the final report is due in mid-February.
"Our research program is pure science. We are not dealing with policies," said Guido Franco, senior engineer with the California Energy Commission's public-interest energy research program. "But if we don't start acting now, the probability of a change in climate in a way that would be dangerous to society increases. And the state that develops clean technologies -- technologies that reduce emissions -- will have a competitive advantage."
What happens in the state could have broad influence. If California were a nation, it would be the fifth-biggest economy in the world and the 12th-biggest generator of greenhouse gases, such as carbon dioxide and methane, that trap heat and warm climate. It's also been an environmental trendsetter, from the nation's toughest standards for tailpipe emissions to a program approved this month to subsidize the installation of solar panels on 1 million roofs.
"I think that within this country California is leading the way," said Lisa Sloan, director of the Climate Change and Impacts Laboratory at the University of California-Santa Cruz.
At the same time, researchers say, we're especially vulnerable.
More than one-third of California's usable water supply comes from melting Sierra Nevada snow.
Even if people do all they can to reduce greenhouse gas emissions, levels will climb, raising temperatures 3 to 5 degrees by the end of the century. That would shrink the Sierra snowpack 30 to 60 percent, according to the state's draft report. At worst, the snowpack could shrink 90 percent.
No matter what the scenario, the sea level would rise and heat waves, smoggy days and wildfires would become more common, while demand for electricity would soar.
That general prognosis has been understood for some time. The new computer models allow scientists to divide the state into much smaller regions than ever before -- just six miles on a side.
Regional analyses
These regional models give scientists a way of "draping climate over our complex landscape," said Daniel Cayan, a climate change researcher with the U.S. Geological Survey and Scripps Institution of Oceanography in La Jolla.
For example, in a study led by Lara Kueppers at UC-Santa Cruz, scientists found that the ranges of two native oaks could move northward, get pushed to higher elevations and shrink by more than 50 percent under a business-as-usual climate scenario.
In the process, the oaks would disappear from more than half the protected lands where they now grow.
"Oaks in general are kind of an iconic species of the California landscape," Kueppers said. The ranges of both blue and valley oaks are already limited, she said. Like other oaks, they're threatened by development, cutting for firewood, vineyard expansions and hungry cattle, she said.
California is part of an internationally recognized "hot spot" of biodiversity that extends north across the Oregon border and south into Baja California. It's home to 4,426 species of plants, nearly half of which are found nowhere else, said Lee Hannah, a climate change biologist with Conservation International. Seventy-one of the hot spot's vertebrates -- animals with backbones -- live only in California.
"We know that species move their ranges when climate changes," Hannah said. "We have to begin to look at if our protected areas are in the right places."
Scientists are also looking beyond the greenhouse effect.
For instance, urban development warms climate; cities give off more heat than natural areas and also absorb more heat from the sun, a phenomenon known as the "urban heat island effect."
On the other hand, widespread irrigation can cool climate and make it more humid.
One study at UC-Santa Cruz used a computer model to look back 150 years and see how development and irrigation might have affected temperatures in the Central Valley. The result: Irrigated areas appear about 4 degrees cooler and developed areas about 4 degrees warmer than those with natural vegetation.
Even events halfway across the world can have an impact: A 2004 study by Jacob Sewall of UC-Santa Cruz concluded that melting Arctic ice could shift the winter storm track northward, so central and Southern California get less rain and snow.
"There's a lot at stake," Cayan said, "and we think the vulnerability of our state, our society, our ecosystems to these climate influences is such that you probably want to do what we can to avoid the really high rates of emissions."
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