Warmer Weather Threatens Western Water Supplies
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RICHLAND, Washington, November 22, 2002 (ENS) – A warming climate will put increasing pressure on water supplies in western states, new research suggests.
In the most rigorous study to date of potential greenhouse impacts, a group of leading global warming and climate change researchers detail how major water problems could evolve over the next 50 years throughout the West as a result of climate change already underway. The report was written by more than two dozen scientists and engineers from around the country.
The new simulations, released Thursday, suggest the effects of rising temperatures will exacerbate problems that are already beginning to emerge. In the West, the effects of global warming can already be seen in earlier melting of mountain snow packs and spring flooding dates.
Scientific studies show that these, and other expected climate changes, could have a devastating impact on water resources in some parts of the West over the next half century.
“Population and economic growth already are placing severe pressure on water resources in the West. Climate change is one more very important factor that has to be taken into account when thinking about the future,” said Bill Pennell, director of the atmospheric science and global change division at Pacific Northwest National Laboratory (PNNL).
Among the conclusions of the PNNL research team:
In the Columbia River System of Washington State, residents and industries may be faced with the choice of water for summer and fall hydroelectric power or spring and summer releases for salmon runs, but not both. Accelerated Climate Prediction Initiative research, or ACPI, shows that with climate change, the river cannot be managed to accommodate both. In fact, the window for successful salmon reproduction in the Pacific Northwest may become so compressed by climate change that some species could cease to exist regardless of any current or future water policies.
The Colorado River Reservoir System will not be able to meet all of the demands placed on it – including water supply for Southern California and the inland Southwest – because reservoir levels will be reduced by more than one-third and releases by as much as 17 percent. The greatest effects will be on lower Colorado River Basin states. All users of Colorado River hydroelectric power will be affected by lower reservoir levels and flows, which will result in reductions in hydropower generation by as much as 40 percent.
In the Central Valley of California, it will be impossible to meet current water system performance levels so that impacts will be felt in reduced reliability of water supply deliveries, hydropower production and instream flows. With less fresh water available, the Sacramento Delta could experience an increase in salinity, causing major ecosystem disruptions.
“It also is important to point out that these predictions are based on one of the most conservative climate models,” said Dennis Lettenmaier, professor of civil engineering at the University of Washington. “Other models show a much larger warming effect.”
“However, even this conservative model indicates substantial changes,” Lettenmaier cautioned. “For example, by mid-century the yearly average snow pack in the Washington and Oregon Cascades may be reduced on the order of 50 percent and because most of our water storage is in this snow pack, such a reduction will result in big changes in flows and water temperatures in Cascade rivers and streams.”
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Posted by: Paul on November 24, 2002 at 21:35:25