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Future Looks Hot
U.N. Panel Says Warming Is Worse Than Previously Believed
By H. Josef Hebert
The Associated Press
W A S H I N G T O N, Oct. 26 — New evidence shows
man-made pollution has “contributed
substantially” to global warming and the earth is
likely to get a lot hotter than previously
predicted, a United Nations-sponsored panel of
hundreds of scientists finds.
The conclusions by the Intergovernmental Panel on
Climate Change, the most authoritative scientific voice on the
issue, is expected to widely influence climate debate over the
next decade.
The report’s summary, a copy of which was obtained by
The Associated Press, was being distributed to government
officials worldwide this week.
It is the first full-scale review and update of the state of
climate science since 1995 when the same panel concluded
there is “a discernible human influence” on the earth’s
climate because of the so-called “greenhouse” effect caused
by the buildup of heat-trapping chemicals in the atmosphere.
Panel Revises Assessment
The panel says in its new assessment that now “there is
stronger evidence” of the human influence on climate and
that it is likely that manmade greenhouse gases already
“have contributed substantially to the observed warming over
the last 50 years.”
And the scientists, in revised estimates, conclude that if
greenhouse emissions are not curtailed the earth’s average
surface temperatures could be expected to increase from 2.7
to nearly 11 degrees Fahrenheit (1.5 to 6 Celsius) by the end
of this century, substantially more than estimated in its
report five years ago.
It attributes the increase — from a range 1.8 to 6.3
degrees Fahrenheit (1 to 3.5 Celsius) warmer in the 1995
assessment — mainly to a reduced influence now expected
to be played by sulfate releases from industry and power
plants. Such releases, which tend to have a cooling
influence, will likely dramatically decline in industrial
countries because of other environmental concerns, the
scientists maintain.
“What this report is clearly saying is that global warming
is a real problem and it is with us and we are going to have
to take this into account in our future planning,” said Kevin
Trenberth, head of climate analysis section at the National
Center for Atmospheric Research.
“It definitely reinforces what we were able to say in
1995,” added Tom Wigley, a climate scientist at the center in
Boulder, Colorado. “It shows the previous projections (in
1990 and 1995) were conservative.”
Wigley, who did not participate in crafting the latest
findings, was a key author of the 1995 report’s section about
the human impact on climate.
Others were less certain.
Some Scientists Still Skeptical
Michael Schlesinger, a climatologist at the University of
Illinois at Champaign-Urbana said despite the new
information there is still insufficient knowledge about natural
climate variables such as solar radiation that could change
the assessment.
Comparing studies of climate to listening to noise radio
transmissions, Schlesinger said in an interview, “Science has
moved closer to the radio transmitter, so the signal is higher
and more apparent against the background noise. But the
background noise has not diminished. There are still
uncertainties and there may be very large surprises ahead.”
The IPCC’s third assessment report is expected to get
final approval at a United Nations conference early next year.
While some wording will certainly be changed by
government policy-makers, the central scientific conclusions
may not be altered, several scientists who have been
involved in the process said Wednesday.
Michael Oppenheimer, an atmospheric physicist at
Environmental Defense, said the latest assessment
“reinforces the mainstream scientific consensus” about
global warming. Its new estimates of warming poses “a risk
of devastating consequences within this century.”
Major Polluters Ignore Kyoto Accord
Three years ago industrial nations tentatively agreed to
curtail the release of greenhouse gases — mainly carbon
dioxide from burning fossil fuels — to below 1990 levels as a
first step to address global warming.
But none of the major industrial countries has yet ratified
the agreement, crafted in Kyoto, Japan in 1997. Skeptics
argue that the science has yet to be conclusive and that
computer models used to predict future climate is not
reliable enough to warrant a dramatic, and possibly very
expensive, shift in energy use to curtail carbon emissions
into the atmosphere.
The issue also has crept into the presidential campaign.
Vice President Al Gore has argued the science is clear and
steps need to be taken soon to begin reducing greenhouse
emissions. His Republican rival, Texas Gov. George W. Bush,
has not dismissed global warming, but urges a cautious
approach and believes the science still needs to be proven.
The IPCC panel’s summary of a voluminous technical
report covering 14 chapters attempts to provide the most
current state of scientific understanding of the climate
system and potential for future warming.
While there are still uncertainties, the IPCC scientists say
that there is an “increasing body of observations” that
provide a “collective picture of a warming world” that cannot
be solely explained by natural forces.
“Emissions of greenhouse gases and aerosols due to
human activities continue to alter the atmosphere in ways
that affect the climate system,” the report says.
Various findings of the last five years have reinforced the
IPPC’s 1995 determination that climate change warrants
top-level attention by government policy makers. |
