Shawn Alladio
01-22-2007, 10:48 PM
http://www.timesheraldonline.com/ci_5060826
California could die of thirstGlobal warming cuts snowpack, raises sea level
By Mike Taugher, MediaNews Group
Article Launched: 01/22/2007 07:02:42 AM PST
Editor's note: This is the second day of a series on the effects of global warming on California
At the Golden Gate, the sea is rising.
In the Sierra Nevada, the snowpack is shrinking.
These developments, attributable to a warming climate, threaten one of California's most indispensable resources: water.
Without water and the ability to move it efficiently over hundreds of miles - to cities, suburbs, farms and factories - California would not be the highly developed, fertile and industrial powerhouse it is today.
The threats to California's water supply, in many ways the state's lifeblood, are not mere possibilities.
They are here. And now.
"What we're beginning to see clearly in California - and these are not projections - is ... a sea level rise of about a half a foot at the Golden Gate. That's real data," said John Andrew, chief of special planning for the state Department of Water Resources.
"The snow coming down from the Sierra - earlier snowmelt - that's real data."
Many scientists say those trends will hasten in the coming decades and reach troublesome levels as the climate continues to absorb increased greenhouse gases from motor vehicles, power plants and other sources.
Water, already
the subject of perpetual and fierce battles among farmers, urban water agencies and environmentalists, will become even more scarce.
The effects of a warming climate are already being measured all over the world, from the Arctic to Antarctica.
In California, tide gauges have recorded a sea-level rise of about 7 inches at the Golden Gate during the past 100 years. Throughout the West, spring is arriving sooner. Snowmelt in the Sierra Nevada now starts at least a week earlier than it did before World War II. And more precipitation in California is falling as rain rather than snow. That's all bad news.
In the western United States, where crops generally require irrigation and states depend on mountain snowpack to water their farms and cities, a warming climate means less snow. And that means less water for the summer.
A rising sea means the fragile Delta levees that protect farms, houses and the state's primary water delivery system will come under increased pressure when the high tides roll in. More sea salt will be pushed toward the state's main Delta drinking and irrigation water intakes.
For a hint of what a warmer California might look like, recall May 2005. A spring storm moved into California, which was warmer than usual. At relatively high elevations around Yosemite National Park, where the storm clouds would normally drop snow, it rained.
The rain quickly washed into tributaries and streams that rapidly filled and broke riverbanks in the low-lying areas, causing widespread flooding in Yosemite Valley. Campgrounds were drowned, water pooled on thoroughfares and park officials closed Yosemite Valley for a day. It was a relatively small storm that caused an unusual amount of havoc.
"This is an analogue of what might happen," said Daniel Cayan of the Scripps Institution of Oceanography at the University of California, San Diego. "As time goes on, we're expecting those warmer storms to be more frequent."
"It happens slowly, so we're kind of like that frog in the water that's boiling - you might not notice it until there's some real consequences," said Steve Hall, executive director of the Association of California Water Agencies.
In the worst case, the Sierra snowpack could shrink by as much as 90 percent, some computer models suggest.
"That rain/snow line is going to rise to the summit" in much of the northern Sierra Nevada, said Jeff Mount, director of the Center for Watershed Sciences at UC Davis. "That changes everything."
Although Mount Shasta, the tallest peak in Northern California, would continue to boast a snowpack, much of the Sierra Nevada from Lake Tahoe north could have dramatically less snow.
Without slow-melting snow, runoff in rivers such as the Feather, Yuba and American could be very high while the rain is falling, then very low as the watershed drains.
More than 150 peer-reviewed scientific papers have been published on climate change and California's water, studies that range from technical reports meant to improve how scientists can more accurately regionalize climate change projections, to how Californians might adapt to them, to documenting changes already taking place.
"There's an increasingly clear message that we're already here," said Peter Gleick, president of the Oakland-based Pacific Institute, who helped write a summary of those studies for water officials in 2003.
In the mid-1980s, Gleick published the first detailed assessment of how climate change would affect California's water supply. He concluded that the state would see more rain, less snow and a greater risk of floods and drought - conclusions that have only strengthened with time.
Gleick is firmly in the scientific mainstream when he says that humans are at least partly responsible for global warming.
"I can't tell you if it's 80-20, 70-30, 60-40 or 50-50," Gleick said. "But we can't explain the changes that we're seeing without invoking human influences. They cannot be just the results of natural variability."
The human fingerprint on climate change is becoming clearer, both globally and in California.
Six years ago, a team of scientists using data from stream gauges and records gathered by gardeners and other volunteers of when lilacs and honeysuckles first bloom found that spring has been arriving earlier in Western states since the 1970s. Scientists hypothesized that the shift was caused by a natural climate fluctuation.
The phenomenon, known as the Pacific Decadal Oscillation, affects weather patterns and is associated with water temperatures in the northern Pacific that tend to switch back and forth between warm and cool phases every couple of decades or so.
If the spring warming was largely caused by the oscillation, that would mean that the earlier snowmelt and blooms were simply an expression of the natural rhythm.
But in subsequent studies, natural causes were mostly rejected as an adequate explanation.
A more detailed 2005 paper in the Journal of Climate, which considered four years of additional data, confirmed the early blooming trend.
And it added that stream gauges from mountainous watersheds throughout the Western states continued to show spring runoff coming one to four weeks earlier - even though the weather had shifted back to its cooler phase after the summer of 1998.
Despite the end of 21 years in the warm phase, the onset of spring was continuing to creep back earlier in the year.
"Our analysis suggests that (the natural weather pattern) contributes to some of the observed trends but is not sufficient to explain them all," the paper's authors wrote.
California could die of thirstGlobal warming cuts snowpack, raises sea level
By Mike Taugher, MediaNews Group
Article Launched: 01/22/2007 07:02:42 AM PST
Editor's note: This is the second day of a series on the effects of global warming on California
At the Golden Gate, the sea is rising.
In the Sierra Nevada, the snowpack is shrinking.
These developments, attributable to a warming climate, threaten one of California's most indispensable resources: water.
Without water and the ability to move it efficiently over hundreds of miles - to cities, suburbs, farms and factories - California would not be the highly developed, fertile and industrial powerhouse it is today.
The threats to California's water supply, in many ways the state's lifeblood, are not mere possibilities.
They are here. And now.
"What we're beginning to see clearly in California - and these are not projections - is ... a sea level rise of about a half a foot at the Golden Gate. That's real data," said John Andrew, chief of special planning for the state Department of Water Resources.
"The snow coming down from the Sierra - earlier snowmelt - that's real data."
Many scientists say those trends will hasten in the coming decades and reach troublesome levels as the climate continues to absorb increased greenhouse gases from motor vehicles, power plants and other sources.
Water, already
the subject of perpetual and fierce battles among farmers, urban water agencies and environmentalists, will become even more scarce.
The effects of a warming climate are already being measured all over the world, from the Arctic to Antarctica.
In California, tide gauges have recorded a sea-level rise of about 7 inches at the Golden Gate during the past 100 years. Throughout the West, spring is arriving sooner. Snowmelt in the Sierra Nevada now starts at least a week earlier than it did before World War II. And more precipitation in California is falling as rain rather than snow. That's all bad news.
In the western United States, where crops generally require irrigation and states depend on mountain snowpack to water their farms and cities, a warming climate means less snow. And that means less water for the summer.
A rising sea means the fragile Delta levees that protect farms, houses and the state's primary water delivery system will come under increased pressure when the high tides roll in. More sea salt will be pushed toward the state's main Delta drinking and irrigation water intakes.
For a hint of what a warmer California might look like, recall May 2005. A spring storm moved into California, which was warmer than usual. At relatively high elevations around Yosemite National Park, where the storm clouds would normally drop snow, it rained.
The rain quickly washed into tributaries and streams that rapidly filled and broke riverbanks in the low-lying areas, causing widespread flooding in Yosemite Valley. Campgrounds were drowned, water pooled on thoroughfares and park officials closed Yosemite Valley for a day. It was a relatively small storm that caused an unusual amount of havoc.
"This is an analogue of what might happen," said Daniel Cayan of the Scripps Institution of Oceanography at the University of California, San Diego. "As time goes on, we're expecting those warmer storms to be more frequent."
"It happens slowly, so we're kind of like that frog in the water that's boiling - you might not notice it until there's some real consequences," said Steve Hall, executive director of the Association of California Water Agencies.
In the worst case, the Sierra snowpack could shrink by as much as 90 percent, some computer models suggest.
"That rain/snow line is going to rise to the summit" in much of the northern Sierra Nevada, said Jeff Mount, director of the Center for Watershed Sciences at UC Davis. "That changes everything."
Although Mount Shasta, the tallest peak in Northern California, would continue to boast a snowpack, much of the Sierra Nevada from Lake Tahoe north could have dramatically less snow.
Without slow-melting snow, runoff in rivers such as the Feather, Yuba and American could be very high while the rain is falling, then very low as the watershed drains.
More than 150 peer-reviewed scientific papers have been published on climate change and California's water, studies that range from technical reports meant to improve how scientists can more accurately regionalize climate change projections, to how Californians might adapt to them, to documenting changes already taking place.
"There's an increasingly clear message that we're already here," said Peter Gleick, president of the Oakland-based Pacific Institute, who helped write a summary of those studies for water officials in 2003.
In the mid-1980s, Gleick published the first detailed assessment of how climate change would affect California's water supply. He concluded that the state would see more rain, less snow and a greater risk of floods and drought - conclusions that have only strengthened with time.
Gleick is firmly in the scientific mainstream when he says that humans are at least partly responsible for global warming.
"I can't tell you if it's 80-20, 70-30, 60-40 or 50-50," Gleick said. "But we can't explain the changes that we're seeing without invoking human influences. They cannot be just the results of natural variability."
The human fingerprint on climate change is becoming clearer, both globally and in California.
Six years ago, a team of scientists using data from stream gauges and records gathered by gardeners and other volunteers of when lilacs and honeysuckles first bloom found that spring has been arriving earlier in Western states since the 1970s. Scientists hypothesized that the shift was caused by a natural climate fluctuation.
The phenomenon, known as the Pacific Decadal Oscillation, affects weather patterns and is associated with water temperatures in the northern Pacific that tend to switch back and forth between warm and cool phases every couple of decades or so.
If the spring warming was largely caused by the oscillation, that would mean that the earlier snowmelt and blooms were simply an expression of the natural rhythm.
But in subsequent studies, natural causes were mostly rejected as an adequate explanation.
A more detailed 2005 paper in the Journal of Climate, which considered four years of additional data, confirmed the early blooming trend.
And it added that stream gauges from mountainous watersheds throughout the Western states continued to show spring runoff coming one to four weeks earlier - even though the weather had shifted back to its cooler phase after the summer of 1998.
Despite the end of 21 years in the warm phase, the onset of spring was continuing to creep back earlier in the year.
"Our analysis suggests that (the natural weather pattern) contributes to some of the observed trends but is not sufficient to explain them all," the paper's authors wrote.