CLIMATE WARMING TO SHRINK KEY WATER SUPPLIES AROUND THE WORLD
Posted on Wednesday, November 16, 2005 @ 21:50:04 UTC by vlad
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In the looming future, global warming will reduce glaciers and storage
packs of snow in regions around the world, causing water shortages and
other problems that will impact millions of people. That is the
conclusion of researchers at Scripps Institution of Oceanography at the
University of California, San Diego, and the University of Washington
in a review paper published in the November 17 issue of the journal
Nature.
In analyzing several scenarios,
Scripps Institution’s Tim Barnett, and Jennifer Adam and Dennis
Lettenmaier of the University of Washington, show that human-produced
greenhouse gases, and the resulting warmer climates they produce, will
have a significant influence on ice- and snow-dependent regions and
will result in costly disruptions to water supply and resource
management systems.
In fact, the authors argue that their predictions and observations
“portend important issues for the water resources of a substantial
fraction of the world’s population.”
The analysis first describes how water resource levels will change
under global warming’s influence and then depicts impacts on regions in
the western United States, Europe, Canada, Asia and South America.
According to the authors, the forces driving these
changes—described as “greenhouse physics”—show that in a warming
climate more water will fall in the form of rain rather than snow,
filling reservoirs to capacity earlier than normal. Additionally, a
warming climate will result in snow melting earlier in the year than in
previous decades, disrupting the traditional timing of water available
from snow runoff streams. Together, they say, these changes mean less
snow accumulation in the winter and earlier snow-derived water runoff
in the spring, challenging the capacities of existing water reservoirs.
According to Barnett, water shortages will occur in areas where
reservoir capacity cannot hold the annual cycle of rain/snow.
“California, and in particular the Columbia Basin, doesn’t have
enough dam capacity to hold a seasonal cycle of water,” said Barnett.
“When you change the seasonality of how rivers flow you are essentially
putting the water runoff all into spring rather than being able to draw
it out through summer. Mother nature is not going to act like a
reservoir as it has in the past and when the water comes out all at
once there isn’t enough capacity to contain it.”
For Canada, the authors say earlier spring water runoff will
threaten agricultural production in the Canadian Prairies. In Europe,
hydrological simulations show that climate warming in the Rhine River
Basin may reduce peak-demand water availability for industrial
applications, agriculture and household uses. Ship transportation,
flood protection, hydropower generation and revenue from skiing all
could be threatened as a result.
In 2001, Barnett and other scientists with the Accelerated Climate
Prediction Initiative estimated that vital water resources derived from
the Sierra Nevada may suffer a 15- to 30-percent reduction in the 21st
century as a result of changes in snowpack runoff.
The authors of the new study extended these ideas to regions that
heavily depend on glacier-derived water for their main dry season water
supply. Such regions contrast with those that depend on water derived
from snowpack, such as the western U.S., where water supplies are
replenished each year. Thus, the researchers warn that “even more
serious problems may occur” in glacier dependent regions “because once
the glaciers have melted in a warmer world, there will be no
replacement for the water they now provide.”
Barnett,
Adam and Lettenmaier say the most vulnerable region where vanishing
glaciers will impact water supplies in the coming decades is China,
India and other parts of Asia because of their potential to affect vast
populations throughout this region. The ice mass in the mountainous
area of this region is the third largest on Earth following
Arctic-Greenland and Antarctica.
In South America, a significant fraction of the population west of
the Andes Mountains similarly could be at risk due to shrinking
supplies of glacier-derived river water. Glacier-covered areas in Peru,
for instance, have experienced a 25 percent reduction in the past three
decades, the authors note, and “at current rates some of the glaciers
may disappear in a few decades, if not sooner.” Here again they warn
that fossil water lost through glacial melting will not be replaced in
the foreseeable future.
Adding to the complexity of these scenarios is determining the role
of tiny atmospheric particles called aerosols. Such particles are
believed to cool the planet’s surface and alter cloud processes. But
while common aerosols such as black carbon are found in many regions
around the world, their influence is not likely to reverse or even
neutralize greenhouse warming, the authors say.
“Climate warming is a certainty in our future and the bottom line
in this analysis is that we looked at the impact of the warming and the
long-term prognosis is clear and very dire,” said Barnett. “It’s
especially clear that regions in Asia and South America are headed for
a water supply crisis because once that fossil water is gone, it’s
gone.”
The research described in the Nature paper is a contribution from
the International Detection and Attribution Group, jointly supported by
the National Oceanic and Atmospheric Administration and the U.S.
Department of Energy. The gross domestic product data set was developed
by the Center for International Earth Science Information Network at
Columbia University in Palisades, New York, with funding from the
National Aeronautics and Space Administration.
Note to broadcast and cable producers: UCSD provides an on-campus satellite uplink facility for live or pre-recorded television interviews. Please phone or e-mail the media contact listed above to arrange an interview.
Source: University of California, San Diego
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RANKS OF 'ENVIRONMENTAL REFUGEES' SWELL, November 16
Amid predictions that by 2010 the world will need to cope with as many
as 50 million people escaping the effects of creeping environmental
deterioration, United Nations University experts say the international
community urgently needs to define, recognize and extend support to
this new category of 'refugee'.
Full story at http://www.physorg.com/news8213.html
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