Global Warming Study Predicts Wild Ride
Pastor Dale Morgan
Oct 21, 10:46 PM EDT
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Global Warming Study Predicts Wild Ride
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By SETH BORENSTEIN
AP Science Writer
WASHINGTON (AP) -- The world - especially the Western United States, the
Mediterranean region and Brazil - will likely suffer more extended
droughts, heavy rainfalls and longer heat waves over the next century
because of global warming, a new study forecasts.
But the prediction of a future of nasty extreme weather also includes
fewer freezes and a longer growing season.
In a preview of a major international multiyear report on climate change
that comes out next year, a study out of the National Center for
Atmospheric Research details what nine of the world's top computer
models predict for the lurching of climate at its most extreme.
"It's going to be a wild ride, especially for specific regions," said
study lead author Claudia Tebaldi, a scientist at the federally funded
academic research center.
Tebaldi pointed to the Western U.S., Mediterranean nations and Brazil as
"hot spots" that will get extremes at their worst, according to the
computer models.
And some places, such as the Pacific Northwest, are predicted to get a
strange double whammy of longer dry spells punctuated by heavier rainfall.
As the world warms, there will be more rain likely in the tropical
Pacific Ocean, and that will change the air flow for certain areas, much
like El Nino weather oscillations now do, said study co-author Gerald
Meehl, a top computer modeler at the research center. Those changes will
affect the U.S. West, Australia and Brazil, even though it's on South
America's eastern coast.
For the Mediterranean, the issue has more to do with rainfall in the
tropical Atlantic Ocean changing air currents, he said.
"Extreme events are the kinds of things that have the biggest impacts,
not only on humans, but on mammals and ecosystems," Meehl said. The
study, to be published in the December issue of the peer-reviewed
journal Climatic Change, "gives us stronger and more compelling evidence
that these changes in extremes are more likely."
The researchers took 10 international agreed-upon indices that measure
climate extremes - five that deal with temperature and five with
precipitation - and ran computer models for the world through the year
2099. What Tebaldi called the scariest results had to do with heat waves
and warm nights. Everything about heat waves - their intensity, length
and occurrence - worsens.
"The changes are very significant there," Tebaldi said. "It's enough to
say we're in for a bad future."
The measurement of warm nights saw the biggest forecast changes. Every
part of the globe is predicted to experience a tremendous increase in
the number of nights during which the low temperature is extremely high.
Those warm night temperatures that should happen only once every decade
will likely occur at least every other year by the time we reach 2099,
if not more frequently, Tebaldi said.
Warm nights are crucial because Chicago's 1995 heat wave demonstrated
that after three straight hot nights, people start dying, Meehl said.
However, heat wave deaths are decreasing in the United States because
society has learned to adapt better, using air conditioning, noted
University of Alabama at Huntsville atmospheric sciences professor John
Christy. He is one of a minority of climate scientists who downplay the
seriousness of global warming.
Similarly, the days when the temperature drops below freezing will
plummet worldwide. That's not necessarily a good thing, because fewer
frost days will likely bring dramatic change in wildlife, especially bug
infestation, Tebaldi said.
"It's a disruption of the equilibrium that's been going for many
centuries," Tebaldi said. But she noted that a lengthier growing season
in general is good.
"This notion of the greening of the planet ... generally is a positive
benefit," Christy said.
Christy, who did not participate in the study but acknowledges that
global warming is real and man-made, said an increase in nighttime low
temperatures makes much more sense than the rain-and-drought forecasts
of the paper.
One of the larger changes in precipitation predicted is in the intensity
of rain and snowfall. That means, Tebaldi said, "when it rains, it rains
more" even if it doesn't rain as often.
Tebaldi's assessment jibes with the National Climatic Data Center's
tracking of extreme events in the United States, said David Easterling,
chief of the center's scientific services. Easterling's group has
created a massive climate extreme index that measures the weather in
America. Last year, the United States experienced the second most
extreme year in 95 years; the worst year was in 1998.
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On the Net
"Going to the Extremes" study:
http://www.cgd.ucar.edu/ccr/publications/klu-multimodel-extremes-revised.pdf
U.S. government's climate extreme index: