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- Warmer, wetter winters. Hotter, drier summers. Species
disappearing and fish stocks in flux. More floods, landslides, wildfires,
pests and pestilence.
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- Signs of the apocalypse?
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- Actually, those changes are likely in California's future,
according to a two-year study released Thursday.
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- The prestigious panel of the nonprofit Union of Concerned
Scientists and the Ecological Society of America concludes that shifts
in temperature and rainfall over the next century will probably reduce
the already scarce supply of fresh water.
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- "There's good evidence that the climate will change
globally, and it will change in California," said Christopher B. Field,
lead author and faculty member of Carnegie Institution of Washington's
Department of Plant Biology on the Stanford University campus.
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- "The best available evidence indicates warming over
the next century of 5 to 6 degrees Fahrenheit in the winter and 1 to 2
degrees in the summer," Field said. "The evidence also indicates
wetter winters and probably drier summers. All the changes acting together
will have a profound effect on water resources in California."
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- Some of the predictions of "Confronting Climate
Change in California: Ecological Impacts on the Golden State," the
62-page study:
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- Summer water shortages could intensify competition for
water among cities, farms, businesses and ecosystems that depend on rivers
and runoff. Grapes, cotton, alfalfa and other crops that use lots of water
may reap smaller profits. Droughts could intensify economic and environmental
loss from wildfires and damage to forests from pine bark beetles.
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- Less fresh water entering the Bay would change water
salinity, quality and circulation, disrupting the food chain. This could
threaten the commercial supplies of anchovies and herring and endangered
salmon and steelhead trout.
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- More winter rain could cause flooding " including
along 1,100 miles of Delta waterways " landslides, erosion and risks
of waterborne and pest-borne diseases. A one-foot rise in sea level from
melting icecaps by 2100 means that reaching high-tide peak on the lower
San Joaquin River would change from an event that occurs every 100 years
on average to every 10 years.
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- El Nios, which have had a particularly dramatic effect
on California's weather and economy, may increase in intensity and frequency
as the climate changes. These turbulent weather patterns would amplify
the impact of the rise in sea level on coastal wetlands, agriculture and
housing.
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- Even though winters may be wetter, warmer weather means
more of the precipitation would be rain that would fill rivers, the study
found, instead of snow that
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- would build a Sierra snowpack.
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- "That means we'll have much more winter runoff,"
said Field. "By the time you get into the summer, the stream flow
may be less. Warmer summers increase evaporation, which will further increase
water shortage."
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- The Intergovernmental Panel on Climate Change, a group
of more than 500 scientists, concluded in 1995 that warming would increase
between 2 and 6 degrees Fahrenheit in the next 100 years, the fastest pace
in human history.
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- Most of the climate change is driven by human activities,
it said, as carbon dioxide is released by burning fossil fuels, and, to
a lesser degree, its removal from the atmosphere is decreased by the cutting
of forests. The gas traps solar heat within Earth's atmosphere in a greenhouse
effect.
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- Except for a few dissenting voices, scientists agree
the
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- sea level in California will rise by 8 to 12 inches in
the next 100 years, two to three times the increase seen in the Pacific
Ocean at San Francisco over the past 150 years.
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- California already affected
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- The effects of climate change already have begun in California,
some studies show.
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- For example, a warming of the currents off California
in recent decades has been linked to population declines of zooplankton,
tiny creatures at the base of the food chain, and of seabirds called sooty
shearwaters.
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- In kelp forests off the Southern California coast, the
proportion of northern cold-water fish species has dropped by half since
the 1970s. The proportion of southern warm-water fish species has increased
nearly 50 percent.
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- At least one California butterfly species, Edith's checkerspot,
is shifting from the southern to the northern limits of its range, a likely
consequence of rising temperatures.
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- Only in the last decade, with more precise models, could
scientists predict the regional effects of global climate change. The predictions
are still sketchy, but the scientists agree that the changes are likely
to vary
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- widely across the state.
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- One scenario predicts much more rain over California
with dry areas to the east of the Cascades and Sierra Nevada. Winter precipitation
over the coast and Sierra could rise by 25 percent or more, it showed.
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- Another shows the strongest warming in the northern Sierra
and Central Valley, with increased drought in the southeastern corner of
the state.
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- Major shifts in ecosystems
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- The state's changing climate could result in major shifts
in ecosystems, the study predicts. Grassy savannahs would likely encroach
on the arid foothill chaparral of the coastal ranges and the Sierra Nevada.
At higher elevations, shrubs could replace forests. Off the north coast,
changing current temperatures could influence the fog, which is favorable
for redwood forests.
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- California's ecosystems are already vulnerable, sometimes
whittled down to small patches harboring imperiled species.
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- The panel of scientists recommended limiting fossil fuel
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- emissions. In addition, it advised limiting development
to provide more breathing room for ecosystems to deal with climate changes.
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- "It's not all bad news, and there are some things
that can be done," said Field. "We hope the study will help to
consider the environmental consequence of future change, and take steps
to protect these environmental values."
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- The Union of Concerned Scientists is a 30-year-old nonprofit
dedicated to advancing responsible science and technology public policies,
and the Ecological Society of America is an association of 7,000 professional
members. Both are based in Washington D.C.
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