” … agriculture is the human activity that is
most vulnerable to changes in climate.”
Climate changes threaten water crisis in West
Study finds people cause most warming
Last updated January 31, 2008 7:38 p.m. PT
By ERICA WERNER THE ASSOCIATED PRESS
WASHINGTON — People driving their cars, cranking
up their air conditioners and switching on lights
and dishwashers are responsible for most of the
climate changes that are gradually drying up
water supplies in arid and growing Western
states, a new study finds.
Those climate trends are likely to increase,
threatening a water crisis in the western United
States, says the study published Thursday in the
The study is likely to add to urgent calls for
action already coming from Western states
competing for the precious resource to irrigate
farms and quench the thirst of growing
populations. Devastating wildfires, avalanches
and drought have also underscored the need.
Researchers led by climate expert Tim Barnett at
the Scripps Institution of Oceanography at the
University of California-San Diego studied
climate changes in the West between 1950-1999.
They noted that winter precipitation falls
increasingly as rain rather than snow and that
snow melts faster. There are decreased river
flows in summer months. The warming is
aggravating dry summer conditions.
The researchers used statistical modeling to
compare climate changes that would have happened
with natural fluctuations over time, to climate
changes with the addition of human-caused
greenhouse gases and other emissions from
vehicles, power plants and other sources.
They found that up to 60 percent of changes in
river flow, temperature and snow pack between
1950 and 1999 can be attributed to human
activities, such as driving, which release
emissions including carbon dioxide and other
greenhouse gases into the atmosphere.
Another study from the journal found that changes
in climate brought by global warming could cause
major crop losses in many of the world’s poorest
regions within the next two decades
The findings foresee alarming consequences for
many of the 1 billion poor people who depend on
agriculture for their livelihoods, largely
because agriculture is the human activity that is
most vulnerable to changes in climate. The worst
affected areas were projected to be southern
Africa and South Asia, already home to huge
numbers of hungry people.
In the study that focused on the American West,
the changes observed differed significantly from
trends that could be attributed to natural
fluctuations between wet and dry periods over
time, the study’s authors said.
“The climate’s changing in the West. We’ve known
that. The question is why, and no one’s really
addressed that,” Barnett said in an interview.
According to his study, “The answer is it is us.”
Barnett suggested the need for conservation, more
water storage and a slowdown on development in
The study also included researchers from Lawrence
Livermore National Laboratory, the University of
Washington and the National Institute for
Environmental Studies in Japan.
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