Water troubles in the West may worsen

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As temperatures have increased, more winter precipitation has fallen as rain instead of snow, and the snow is melting sooner, reported the study published in the journal Science. The result is that rivers are flowing faster in the spring, raising the risk of flooding, and slower in the summer, raising the risk of drought.

Between 1950 and 1999, the period the researchers examined, the total amount of precipitation that fell in the Rockies, the Cascades, the Sierra Nevada and smaller mountain ranges across the West did not vary significantly. But the portion arriving as snow steadily declined, falling by an average of 4.3% per decade in the nine areas included in the study. Average daily minimum temperatures between January and March climbed an average of 0.34 degrees Celsius per decade.

Human-caused global warming has been shrinking the snowpack across the mountain ranges of the West for five decades, suggesting that the region's long battle for water will only get worse, according to a computer analysis released today.

Based on their simulations, along with historical data on snowpack, temperature and river flow, the researchers concluded that there was a less than 1% chance that the last 50 years were a natural aberration.

Western U.S. Faces Drought Crisis, Warming Study Says

The scientific evidence just keeps screaming at us to change our ways or else...

The U.S. West will see devastating droughts as global warming reduces the amount of mountain snow and causes the snow that does fall to melt earlier in the year, a new study says.

By storing moisture in the form of snow, mountains act as huge natural reservoirs, releasing water into rivers long into the summer dry season.

"We're losing that reservoir," said research leader Tim Barnett, an oceanographer and climate researcher at the University of California, San Diego.

"Spring runoff is getting earlier and earlier in the year, so you have to let water go over the dams into the ocean." Summers are also becoming hotter and longer. "That dries things out more and leads to fires," Barnett added.

"Our results are not good news for those living in the western United States," the scientists write in their report, which appears in today's online edition of the journal Science.

The researchers found that the changes currently affecting the U.S. West have less than a one percent chance of being due to natural variability, Barnett told National Geographic News.