Text 25172, 119 rader
Skriven 2006-11-16 14:04:00 av Jeff Binkley (1:226/600)
Ärende: Global Warming
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This gets better and better with each post............

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http://www.cnn.com/2006/TECH/science/11/16/smog.warming.ap/index.html

Scientists: Pollution could combat global warming
POSTED: 8:22 a.m. EST, November 16, 2006 

NAIROBI, Kenya (AP) -- Air pollution may be just the thing to fight 
global warming, some scientists say.

Prominent scientists, among them a Nobel laureate, said a layer of 
pollution deliberately spewed into the atmosphere could act as a "shade" 
from the sun's rays and help cool the planet.

Reaction to the proposal here at the annual U.N. conference on climate 
change is a mix of caution, curiosity and some resignation to such 
"massive and drastic" operations, as the chief U.N. climatologist 
describes them.

The Nobel Prize-winning scientist who first made the proposal is himself 
"not enthusiastic about it."

"It was meant to startle the policymakers," said Paul J. Crutzen, of 
Germany's Max Planck Institute for Chemistry. "If they don't take action 
much more strongly than they have in the past, then in the end we have 
to do experiments like this."

Serious people are taking Crutzen's idea seriously. This weekend at 
Moffett Field, California, NASA's Ames Research Center hosts a closed-
door, high-level workshop on the global haze proposal and other 
"geoengineering" ideas for fending off climate change.

In Nairobi, meanwhile, hundreds of delegates were wrapping up a two-week 
conference expected to only slowly advance efforts to rein in greenhouse 
gases blamed for much of the 0.6-degree-Celsius (1-degree-Fahrenheit) 
rise in global temperatures in the past century.

The 1997 Kyoto Protocol requires modest emission cutbacks by industrial 
countries -- but not the United States, the biggest emitter of carbon 
dioxide and other heat-trapping gases, because it rejected Kyoto. Talks 
on what to do after Kyoto expires in 2012 are all but bogged down.

When he published his proposal in the journal Climatic Change in August, 
Crutzen cited a "grossly disappointing international political response" 
to warming.

The Dutch climatologist, awarded a 1995 Nobel in chemistry for his work 
uncovering the threat to Earth's atmospheric ozone layer, suggested that 
balloons bearing heavy guns be used to carry sulfates high aloft and 
fire them into the stratosphere.

While carbon dioxide keeps heat from escaping Earth, substances such as 
sulfur dioxide, a common air pollutant, reflect solar radiation, helping 
cool the planet.

Tom Wigley, a senior U.S. government climatologist, followed Crutzen's 
article with a paper of his own October 20 in the leading U.S. journal 
Science. Like Crutzen, Wigley cited the precedent of the huge volcanic 
eruption of Mount Pinatubo in the Philippines in 1991.

Pinatubo poured so much sulfurous debris into the stratosphere that it 
is believed it cooled the Earth by 0.5 degrees Celsius (0.9 degrees 
Fahrenheit) for about a year.

Wigley ran scenarios of stratospheric sulfate injection -- on the scale 
of Pinatubo's estimated 10 million tons of sulfur -- through 
supercomputer models of the climate, and reported that Crutzen's idea 
would, indeed, seem to work. Even half that amount per year would help, 
he wrote.

A massive dissemination of pollutants would be needed every year or two, 
as the sulfates precipitate from the atmosphere in acid rain.

The American scientist said a temporary shield would give political 
leaders more time to reduce human dependence on fossil fuels -- main 
source of greenhouse gases. He said experts must more closely study the 
feasibility of the idea and its possible effects on stratospheric 
chemistry.

Nairobi conference participants agreed.

"Yes, by all means, do all the research," Indian climatologist Rajendra 
K. Pachauri, chairman of the 2,000-scientist U.N. network on climate 
change, said.

But "if human beings take it upon themselves to carry out something as 
massive and drastic as this, we need to be absolutely sure there are no 
side effects," Pachauri said.

Philip Clapp, a veteran campaigner for emissions controls to curb 
warming, also sounded a nervous note, saying, "We are already engaged in 
an uncontrolled experiment by injecting greenhouse gases into the 
atmosphere."

But Clapp, president of the U.S. group National Environmental Trust, 
said, "I certainly don't disagree with the urgency."

American geophysicist Jonathan Pershing, of Washington's World Resources 
Institute, was also wary of unforeseen consequences, but said the idea 
might be worth considering "if down the road 25 years it becomes more 
and more severe because we didn't deal with the problem."

By telephone from Germany, Crutzen said that's what he envisioned: 
global haze as a component for long-range planning. "The reception on 
the whole is more positive than I thought," he said.

Pershing added, however, that reaction may hinge on who pushes the idea. 
"If it's the U.S., it might be perceived as an effort to avoid the 
problem," he said.

NASA said this weekend's California conference will examine "methods to 
ameliorate the likelihood of progressively rising temperatures over the 
next decades." Other such U.S. government-sponsored events are scheduled 
to follow.

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