U.S. Water News Online
PHOENIX -- A new study suggests that a decade of higher
temperatures and shrinking runoff seasons have contributed to the
drought that has crippled Colorado River reservoirs.
The study found warmer temperatures in the West's highest
elevations could reduce winter runoff into the river, a major water
source for Arizona, by as much as 30 percent over the next 50 years.
Even a subtle shift in climate could further weaken a river
already overburdened by growing cities and could lead to chronic
water shortages, especially in Arizona, according to the study.
"This climate disruption is already under way," said Stephen
Saunders, president of the Rocky Mountain Climate Organization, a
Louisville, Colo., group that produced the study.
He said the evidence is clear that climate change "will lead to
more heat, less snow, less water when we need it, and possibly more
Runoff from mountain snow is the weak link in the West's water
supply. It provides as much as 70 percent of the region's water,
including as much as two-thirds of the water used in Arizona's
But warmer weather can result in less snow, which directly reduces
the water supply, or it can melt the snow too early. When that
happens, reservoirs can't store it all, and some of the runoff will
"We're getting warmer at exactly the time of year that snow needs
to store water," said Brad Johnson of Arizona Public Interest
Research Group, which released the climate study. "It's a real threat
to our water supply that we should take seriously and address."
The study urges stronger efforts by the state and federal
governments to reduce so-called greenhouse gases, such as carbon
dioxide, which are produced by combustion of fossil fuels. Many
scientists believe greenhouse gases and other man-made pollutants
have accelerated global warming trends.
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