Global warming has worsened water troubles in the U.S. West, such as steadily shrinking snowpacks along mountain ranges, according to a new study published by the February issue of Science.
The snowpack shrinking, which has continued for five decades, has been mainly attributed to human-caused global warming, said the study .
This suggests that the region's long battle for water will only get worse, according to the research based on computer analysis.
As temperatures have increased, more winter precipitation has fallen as rain instead of snow, and the snow is melting sooner. The result is that rivers are flowing faster in the spring, raising the risk of flooding, and flowing slower in the summer, raising the risk of drought, said the study conducted by scientists at Scripps Institution of Oceanography (SIO) in La Jolla, California.
"The handwriting is on the wall," said lead author Tim Barnett, a marine geophysicist at SIO. "Mother Nature is going to stop being our water banker."
In California, reservoirs already operate on a delicate balance. They are kept well below capacity during the winter as protection against flooding. After the rainy season, they are filled with the spring snowmelt, storing water to be released during the dry summers, said the study.
In the region, average daily minimum temperatures between January and March climbed an average of 0.34 Celsius degrees per decade, according to the study.
To trace the cause of the trend, the researchers used computer climate models to simulate a world with greenhouse gases held at preindustrial levels. They factored in the known fluctuations in solar radiation and changing concentrations of volcanic dust, which reflects the sun's heat back into space, over the second half of the 20th century.
Based on their simulations, along with historical data on snowpack, temperature and river flow, the researchers concluded that there was a less than 1 percent chance that the last 50 years constituted a natural aberration.
One computer model showed that rising concentrations of greenhouse gases accounted for 60 percent of the changes. A second analysis using another climate model calculated a contribution of 35 percent.
The study proposed the following suggestions to confront the coming water changes: building more reservoirs, increasing water conservation and diverting water from agriculture to meet the increasing demand from fast-growing cities.
Source:Xinhua
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