California Faces New Water Shortages, and It's the Trees' Fault

[Buster's Uncle]

California Faces New Water Shortages, and It's the Trees' Fault
Takepart.com
By Todd Woody | 4 hours ago



As drought-stricken California’s climate warms, freshwater runoff from the Sierra Nevada mountain range could fall 26 percent by the end of the century, dealing a devastating blow to the state’s economy, according to a study released Tuesday.

Why? Trees. A lot more trees.

As temperatures rise owing to climate change, now-inhospitable alpine slopes of the Sierra Nevada will become covered with plants and trees. All that vegetation will capture moisture that would otherwise make its way to river basins that provide drinking and irrigation water to families and farms, wrote scientists from the Irvine and Merced campuses of the University of California in a paper published in the Proceedings of the National Academy of Sciences.

Some 20 million Californians depend on mountain runoff for their water supplies, as do 4 billion people worldwide, according to the study.

UC Irvine earth system science professor Michael Goulden and UC Merced engineering professor Roger Bales studied rates of evapotranspiration in the Kings River basin. Evapotranspiration is the combined loss of water by the land and the release of moisture into the atmosphere by plants in the form of water vapor.

The scientists installed instruments to measure rates of water vapor emission and used remote sensing technology to determine that evapotranspiration could jump 28 percent by 2100 in the Kings River basin. That would result in a 26 percent drop in freshwater runoff into the Kings River.

“The Kings River is particularly important for hydroelectric generation and as a source of water for agriculture,” they wrote in the paper, noting the area is home to more than 750,000 people and a multibillion-dollar farming economy. 

Hydropower supplies nearly 15 percent of California's electricity.

The researchers based their estimates on computer models that predict temperatures in California will increase 4.1 degrees Celsius by 2100, leading to high rates of evapotranspiration as vegetation moves farther up mountain slopes.

While the scientists’ findings apply to a single river basin, they said that conditions are similar across the Sierra Nevada.

“This consistency implies a potential widespread reduction in water supply with warming, with important implications for California’s economy and environment,” Goulden and Bales wrote.

The only question, they wrote, was just how fast climate change would accelerate the growth of new mountain forests.


http://news.yahoo.com/california-faces-water-shortages-trees-fault-205019668.html