Global warming to hit rivers hard, analysis finds
Gordon; The News Tribune
A new analysis of the effects of global warming on major Western
rivers concludes temperature increases over the next 50 years will
increase friction over the use of limited water supplies.
The predicted changes include reduced snowpack throughout the Pacific
Northwest and earlier spring thaws. That means trade-offs in the Columbia
River, where summer flows are likely to dwindle, researchers said.
"You can have hydropower or you can have salmon, but you probably
can't have both," said Tim Barnett, a marine physicist at the
Scripps Institute of Oceanography in California.
Barnett coordinated the Accelerated Climate Prediction Initiative,
a 2 1/2-year, $2.5 million project sponsored by the U.S. Department
of Energy. Other contributors included experts from the National Center
for Atmospheric Research, in Boulder, Colo., the Pacific Northwest
National Laboratory in Richland and the University of Washington.
Scientists used sophisticated computers to estimate the effects of
climate change on the Columbia, Sacramento and Colorado rivers. Based
on their predictions, the Colorado and Sacramento rivers won't be
able to deliver the consistent supply of water that users demand for
drinking, agriculture and hydropower.
The latest analysis does not anticipate a shortage of Columbia Basin
irrigation water but predicts persistent problems in the Yakima River
valley, where irrigation supplies already are stretched.
Researchers based their predictions on a conservative climate model
that plays down the likelihood of temperature increases.
"This really is giving you a best-case scenario, which is scary,"
The new projection for the Pacific Northwest is less dramatic than
one completed in 1999 by UW researchers, who performed a similar,
but less detailed regional analysis using different computer models.
The new Pacific Northwest forecast predicts a 2- or 3-degree increase
in average annual temperatures within the next 50 years. The previous
prediction suggested temperatures twice as high.
Even so, Phil Mote, the UW atmospheric scientist who authored the
1999 report, said the new analysis vividly underscores the "grave
concern" associated with climate change.
Both studies forecast warmer, wetter winters, with less snow and more
rain in the mountains.
The new analysis predicts a 50 percent reduction of the snowpack in
the Cascades and 30 percent less in the mountains that feed the Columbia
River, said Bill Pennell, one of the research leaders. Pennell, an
atmospheric scientist, is director of atmospheric science and global
change at the Pacific Northwest National Laboratory.
While some experts dispute the risks of global warming, most scientists
agree that excess greenhouse gases, such as carbon dioxide, have altered
the earth's atmosphere. Over the past century, average worldwide temperatures
have risen about a degree. In the Northwest, the increase has been
a little higher.
Most scientists blame industrial pollution and motor vehicle emissions
for the increased carbon dioxide and methane, which are likely to
remain trapped in the atmosphere for as long as 100 years.
In the short term, nothing can be done to reduce greenhouse gases
already there, Pennell said.
"The climate change we're talking about in the next 50 years,
we've already bought into. Climate is kind of like a big freight train.
It takes a while to get going, and it's going be a long time before
it stops," Pennell said.
Consequently, people must adapt. "It's going to force some really
tough changes because not all of these conflicts are going to be resolved
to everybody's satisfaction," he said.
Some people who worry about how climate change will affect hydropower
production and fish already have begun to factor in the likely effects
of climate change.
That's true at the Northwest Power Planning Council, which forecasts
regional energy demand. System analyst John Fazio has worked closely
with the UW researchers who developed the latest predictions for Columbia
River flow. The outlook looks grim for salmon, he acknowledged. "We
just don't have the storage capacity in our reservoirs to hold that
much water to make a difference for fish," he said.
Even so, Kyle Martin, a hydrologist who works for the Columbia River
Intertribal Fish Commission, believes climate change could mean a
reduced likelihood of spring floods, which could allow the U.S. Army
Corps of Engineers to increase the volume of water stored behind dams.
"A lot of water is being flushed out in winter and early spring.
That water is literally being thrown away," Martin said. "We're
not advocating flooding out lower river communities, but the water
would benefit fish and power if it were saved and pushed out later
in the year."