04/20/00 -- A Global Warming Affirmation

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WORLDWIDE FOREST/BIODIVERSITY CAMPAIGN NEWS

A Global Warming Affirmation

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Forest Networking a Project of Forests.org

http://www.climateark.org/ -- Climate Ark

04/20/00

OVERVIEW & COMMENTARY

The Intergovernmental Panel on Climate Change (IPCC) has completed a

preliminary draft of a long anticipated document that indicates humans

have "'discernibly' influenced the planet's climate and the Earth's

surface is likely to warm at least 2 degrees and as much as 9 degrees

Fahrenheit by the end of the 21st century." Rainforests and

atmospheric carbon are closely coupled; and solutions to one crisis

necessarily involve addressing the other. I wanted to draw your

attention the fact that the Climate Ark -- a Climate Change News &

Information Portal and Archive -- is operational at

http://www.climateark.org/ -- providing full text searches of leading

Climate Change research and activist web sites.

g.b.

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RELAYED TEXT STARTS HERE:

Title: A Global Warming Affirmation

Source: Washington Post

Date: April 18, 2000

Byline: Curt Suplee, Washington Post Staff Writer

An early draft of an intently awaited report from the

Intergovernmental Panel on Climate Change (IPCC) contains no surprises

about the prospect of continued global warming, and comes to

approximately the same major conclusions as its celebrated predecessor

five years ago.

According to the new preliminary analysis by the IPCC, an

international collaboration of several hundred scientists sponsored by

the United Nations and the World Meteorological Organization, human

beings have "discernibly" influenced the planet's climate and the

Earth's surface is likely to warm at least 2 degrees and as much as 9

degrees Fahrenheit by the end of the 21st century.

The group's previous assessment, issued in 1995, stated that "the

balance of evidence suggests a discernible human influence on global

climate." The preliminary draft of the new assessment, released for

expert comment yesterday, is somewhat more definitive, indicating that

global warming since 1860--somewhere between 0.7 and 1.5 degrees F,

about 0.2 degree F higher than the 1995 estimates--is "exceptional and

unlikely to be solely natural in origin."

But the range of possible temperature increases, the extent of

potential sea-level increase (4 inches to 3 feet, depending on how

much ice melts and how much the ocean expands from rising

temperatures) and the estimates of additional carbon dioxide in the

atmosphere by 2100 (two to three times the pre-industrial level of

about 280 parts per million) are all extremely similar to the 1995

findings.

In general, improved understanding of world climate during the past

five years has "made for a sharper statement" of the human

contribution this time around, said Kevin E. Trenberth, head of the

Climate Analysis Section at the National Center for Atmospheric

Research in Boulder, Colo., and a lead author on some of the draft

report's sections.

Trenberth said the remarkable warming of the record-setting 1990s,

including the two hottest years on record in 1998 and '97--combined

with better statistical analysis of data, enhanced computer models and

greatly improved ability to reconstruct ancient climates--have

convinced him and many others that man-made "climate change has

emerged from the noise of natural variability."

The new draft, however, echoes the 1995 report in emphasizing several

areas of uncertainty. One is the role of sulfate aerosols--typically

released by fossil fuel combustion--that may serve to discourage

global warming by making clouds shinier.

Other factors include variations in the intensity of sunlight from

decade to decade, and the so-far inexplicable changes in the rate at

which methane, a potent greenhouse gas, enters the atmosphere. The

rate of methane increase has slowed during the past two decades, the

draft report notes, "for reasons that are not clear."

"We probably emphasized a lot more of the negative" elements (that is,

those that tend to mitigate warming) than the 1995 report did,

Trenberth said. And the authors were even more careful to note major

uncertainties, such as the likely amount and distribution of

precipitation in a warmer world. The authors also determined that

potential melting of the West Antarctic Ice Sheet is now regarded as

much less of a threat than gradual decline of the Greenland Ice Sheet.

Not all the authors share Trenberth's view of the new draft report. "I

think, if anything, it is a little bit more uncertain than it was last

time," said Richard S. Lindzen of the Massachusetts Institute of

Technology, a lead author of one section of the 14-chapter report,

which totals nearly 1,000 pages. "We're really no closer to

attributing [global warming since the 19th century] to anything in

particular."

In large measure, that is because of extreme uncertainties about the

role of aerosols and "the assumption that [computer climate] models

are good surrogates for the data," Lindzen said.

D. James Baker, administrator of the National Oceanic and Atmospheric

Administration, said yesterday that his agency would have no comment

on the draft assessment "until we have completed our review of all the

chapters."

The draft material released for comment yesterday is the first of

three parts and focuses specifically on the quality of scientific

research and data underlying the assessment of climate change. During

May, two other IPCC groups are expected to issue drafts of their

reports on coping with impacts of warming and mitigating global

warming.

If all goes as planned, the final version of all three will be

approved in January of 2001 and the entire report published shortly

thereafter. The long process, Trenberth said, "is part of the price

you pay for truly building a consensus."

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