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Globl warming worsening U.S. water crisis

Global warming worsening U.S. water crisis

Global warming worsening U.S. water crisis
January 31, 2008

Human-induced climate change is accelerating a water crisis in the American West, reports a study published this week in the journal Science.

Analyzing shifts in river flow, snow pack and winter air temperatures in the Western United States for the past 50 years, Barnett and colleagues show that up to 60 percent of theses changes can be attributed to human-caused climate change. The authors call for fundamental changes to the science behind water planning and policy.

“Our results are not good news for those living in the western United States,” write the researchers, noting that the changes may make “modifications to the water infrastructure of the western U.S. a virtual necessity.”

The authors say that federal, state and local water agencies “have operated on the premise that historical patterns could be counted on to continue. The assumption was that variability from year to year occurred within stationary, unchanging patterns.” The new research shows these assumptions are no longer safe.

“With the climate changing, past years aren’t necessarily representative of the future anymore,” said co-author Dennis Lettenmaier, a professor of civil engineering at the University of Washington. “This paper says that the way business has been done in the past will no longer work in a changing climate.”

“Historically, looking back at past observations has been a good way to estimate future conditions,” said co-author Christopher Milly, a research hydrologist with the U.S. Geological Survey. “But climate change magnifies the possibility that the future will bring droughts or floods you never saw in your old measurements.”

The researchers say that even with a dramatic reduction in greenhouse gas emissions, warming already set in motion will have impacts on global water infrastructure.

“Our best current estimates are that water availability will increase substantially in northern Eurasia, Alaska, Canada and some tropical regions, and decrease substantially in southern Europe, the Middle East, southern Africa and southwestern North America,” Milly said.

The authors propose integrating climate change projections into a planning framework on water mangement.

“I think it will become increasingly hard to ignore climate change in water management,” said Lettenmaier

T.P. Barnett, et al (2008). Human-induced Changes in the Hydrology of the Western United States. Science 1-Feb-2008

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