http://www.reuters.com/newsArticle.jhtml?type=topNews&storyID=3934811
No
Doubts Global Warming Is Real, U.S. Experts Say
Wed December 3, 2003 10:23 PM ET
WASHINGTON (Reuters)
- There can be no doubt that global warming
is real and is being caused by people, two top U.S. government
climate experts said.
Industrial emissions
are a leading cause, they say -- contradicting
critics, already in the minority, who argue that climate change
could be caused by mostly natural forces.
"There is no doubt
that the composition of the atmosphere
is changing because of human activities, and today greenhouse
gases are the largest human influence on global climate,"
wrote
Thomas Karl, director of the National Oceanic and Atmospheric
Administration's National Climatic Data Center, and Kevin Trenberth,
head of the Climate Analysis Section at the National Center for
Atmospheric Research.
"The likely result
is more frequent heat waves, droughts,
extreme precipitation events, and related impacts,
e.g., wildfires, heat stress, vegetation changes, and
sea-level rise," they added in a commentary to be published
in Friday's issue of the journal Science.
Karl and Trenberth
estimate that, between 1990 and 2100,
there is a 90 percent probability that average global
temperatures will rise by between 3.1 and 8.9 degrees
Fahrenheit (1.7 and 4.9 degrees Celsius) because of human
influences on climate.
Such dramatic warming
will further melt already crumbling
glaciers, inundating coastal areas. Many other groups have
already shown that ice in Greenland, the Arctic and Antarctica
is melting quickly.
Karl and Trenberth
noted that carbon dioxide levels in the
atmosphere have risen by 31 percent since preindustrial times.
Carbon dioxide is the
No. 1 greenhouse gas, causing warming
temperatures by trapping the Sun's energy in the atmosphere.
Emissions of sulfate
and soot particles have significant
effects too, but more localized, they said.
"Given what has
happened to date and is projected in the
future, significant further climate change is guaranteed,"
they wrote.
The United States has
balked at signing international treaties
to reduce climate-changing emissions, but the two experts said
global cooperation is key.
"Climate change
is truly a global issue, one that may prove
to be humanity's greatest challenge," they wrote. "It
is very
unlikely to be adequately addressed without greatly improved
international cooperation and action."
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