Nota liminar: mais um rascunho perdido nas
catacumbas de meu blog, que ainda merece leitura, a despeito da divulgação
Por definição, cientistas que merecem esse nome devem sempre exibir
aquela espécie de ceticismo sadio que os leva a sempre desconfiar das
explicações fáceis, das "teorias gerais" -- keynesianas ou outras --
e procurar mergulhar mais fundo no funcionamento dos fenômenos que estudam,
para oferecer interpretações mais adequadas aos dados reais. Embarcar nas
tendências do momento, seguir a "opinião geral" não deveria ser, em
princípio, uma atitude responsável. Deve-se deixar tal tipo de comportamento
para políticos, feiticeiros e outros palpiteiros atirando a esmo no que não
viram para não acertar no que viram.
Eu sempre desconfio das causas únicas, ou exclusivas, de qualquer
fenômeno natural ou social.
Deveria ser assim também com o aquecimento global.
Vejamos, em todo caso, um artigo que não deveria contentar Al Gore.
The Wall Street Journal,
September 7. 2011
In April 1990, Al Gore
published an open letter in the New York Times "To Skeptics on Global
Warming" in which he compared them to medieval flat-Earthers. He soon
became vice president and his conviction that climate change was dominated by
man-made emissions went mainstream. Western governments embarked on a new era
of anti-emission regulation and poured billions into research that might
justify it. As far as the average Western politician was concerned, the debate
But a few physicists
weren't worrying about Al Gore in the 1990s. They were theorizing about another
possible factor in climate change: charged subatomic particles from outer
space, or "cosmic rays," whose atmospheric levels appear to rise and
fall with the weakness or strength of solar winds that deflect them from the
earth. These shifts might significantly impact the type and quantity of clouds
covering the earth, providing a clue to one of the least-understood but most
important questions about climate. Heavenly bodies might be driving long-term
The theory has now moved
from the corners of climate skepticism to the center of the physical-science
universe: the European Organization for Nuclear Research, also known as CERN.
At the Franco-Swiss home of the world's most powerful particle accelerator,
scientists have been shooting simulated cosmic rays into a cloud chamber to
isolate and measure their contribution to cloud formation. CERN's researchers
reported last month that in the conditions they've observed so far, these rays
appear to be enhancing the formation rates of pre-cloud seeds by up to a factor
of 10. Current climate models do not consider any impact of cosmic rays on
A cutting-edge physics
experiment at the European Organization for Nuclear Research has scientists'
heads in the clouds.
Scientists have been speculating
on the relationship among cosmic rays, solar activity and clouds since at least
the 1970s. But the notion didn't get a workout until 1995, when Danish
physicist Henrik Svensmark came across a 1991 paper by Eigil Friis-Christensen
and Knud Lassen, who had charted a close relationship between solar variations
and changes in the earth's surface temperature since 1860.
"I had this idea
that the real link could be between cloud cover and cosmic rays, and I wanted
to try to figure out if it was a good idea or a bad idea," Mr. Svensmark
told me from Copenhagen, where he leads sun-climate research at the Danish National
He wasn't the first
scientist to have the idea, but he was the first to try to demonstrate it. He
got in touch with Mr. Friis-Christensen, and they used satellite data to show a
close correlation among solar activity, cloud cover and cosmic-ray levels since
They announced their
findings, and the possible climatic implications, at a 1996 space conference in
Birmingham, England. Then, as Mr. Svensmark recalls, "everything went
completely crazy. . . . It turned out it was very, very sensitive to say these
things already at that time." He returned to Copenhagen to find his local
daily leading with a quote from the then-chair of the U.N. Intergovernmental
Panel on Climate Change (IPCC): "I find the move from this pair
scientifically extremely naïve and irresponsible."
Mr. Svensmark had been,
at the very least, politically naïve. "Before 1995 I was doing things
related to quantum fluctuations. Nobody was interested, it was just me sitting
in my office. It was really an eye-opener, that baptism into climate
science." He says his work was "very much ignored" by the
climate-science establishment—but not by CERN physicist Jasper Kirkby, who is
leading today's ongoing cloud-chamber experiment.
On the phone from Geneva,
Mr. Kirkby says that Mr. Svensmark's hypothesis "started me thinking:
There's good evidence that pre-industrial climate has frequently varied on
100-year timescales, and what's been found is that often these variations correlate
with changes in solar activity, solar wind. You see correlations in the
atmosphere between cosmic rays and clouds—that's what Svensmark reported. But
these correlations don't prove cause and effect, and it's very difficult to
isolate what's due to cosmic rays and what's due to other things."
1997 he decided that "the best way to settle it would be to use the CERN
particle beam as an artificial source of cosmic rays and reconstruct an artificial
atmosphere in the lab." He predicted to reporters at the time that, based
on Mr. Svensmark's paper, the theory would "probably be able to account
for somewhere between a half and the whole" of 20th-century warming. He
gathered a team of scientists, including Mr. Svensmark, and proposed the
groundbreaking experiment to his bosses at CERN.
Then he waited. It took
six years for CERN to greenlight and fund the experiment. Mr. Kirkby cites
financial pressures for the delay and says that "it wasn't political."
Mr. Svensmark declines
entirely to guess why CERN took so long, noting only that "more generally
in the climate community that is so sensitive, sometimes science goes into the
By 2002, a handful of
other scientists had started to explore the correlation, and Mr. Svensmark
decided that "if I was going to be proved wrong, it would be nice if I did
it myself." He decided to go ahead in Denmark and construct his own cloud
chamber. "In 2006 we had our first results: We had demonstrated the
mechanism" of cosmic rays enhancing cloud formation. The IPCC's 2007
report all but dismissed the theory.
Mr. Kirkby's CERN
experiment was finally approved in 2006 and has been under way since 2009. So
far, it has not proved Mr. Svensmark wrong. "The result simply leaves open
the possibility that cosmic rays could influence the climate," stresses
Mr. Kirkby, quick to tamp down any interpretation that would make for a good
This seems wise: In July,
CERN Director General Rolf-Dieter Heuer told Die Welt that he was asking his
researchers to make the forthcoming cloud-chamber results "clear, however,
not to interpret them. This would go immediately into the highly political
arena of the climate-change debate."
But while the cosmic-ray
theory has been ridiculed from the start by those who subscribe to the
anthropogenic-warming theory, both Mr. Kirkby and Mr. Svensmark hold that human
activity is contributing to climate change. All they question is its importance
relative to other, natural factors.
Through several more
years of "careful, quantitative measurement" at CERN, Mr. Kirkby
predicts he and his team will "definitively answer the question of whether
or not cosmic rays have a climatically significant effect on clouds." His
old ally Mr. Svensmark feels he's already answered that question, and he
guesses that CERN's initial results "could have been achieved eight to 10
years ago, if the project had been approved and financed."
The biggest milestone in
last month's publication may be not the content but the source, which will be a
lot harder to ignore than Mr. Svensmark and his small Danish institute.
Any regrets, now that
CERN's particle accelerator is spinning without him? "No. It's been both a
blessing and the opposite," says Mr. Svensmark. "I had this field more
or less to myself for years—that would never have happened in other areas of
science, such as particle physics. But this has been something that most
climate scientists would not be associated with. I remember another researcher
saying to me years ago that the only thing he could say about cosmic rays and
climate was it that it was a really bad career move."
that point, Mr. Kirkby—whose organization is controlled by not one but 20 governments—really
does not want to discuss politics at all: "I'm an experimental particle
physicist, okay? That somehow nature may have decided to connect the
high-energy physics of the cosmos with the earth's atmosphere—that's what
nature may have done, not what I've done."
Last month's findings
don't herald the end of a debate, but the resumption of one. That is, if the
politicians purporting to legislate based on science will allow it.
Miss Jolis is an
editorial page writer for The Wall Street Journal Europe.
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