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FREEMAN Dyson, a distinguished physicist, mathematician and
historian of science who also holds a tenured post at the Institute
of Advanced Studies, was called a “pompous twit,” “a cesspool
of misinformation,” “a mad scientist” and other equally ripe
epithets. (Nicholas Dawidoff, New York Times Magazine, March 28,
2009).
Dyson was quoted as having said that abundant
carbon dioxide (CO2) in the atmosphere was good and that it actually
improved rather than worsened Earth’s climate.
He also took a swipe at Al Gore and James Hansen
of NASA’s Goddard Institute for Space Studies for spreading
“lousy science” and for distracting the public from “more
serious and more immediate dangers to the planet.”
Dyson does not deny that there are disruptions
to Earth’s climate but whether they are caused by man or whether
they are part of nature’s cycles is not yet fully known.
He admits that he’s no expert on climate and
that his was “more a matter of judgment rather than knowledge.”
Dyson’s views on planetary ecology were
probably shaped partly by Vaclac Smil’s book, The Earth’s
Biosphere: Evolution, Dynamics and Change (MIT Press, 2002), that he
reviewed with evident approval on May 15, 2009 in The New York
Review of Books.
Dyson began by calling attention to “the
enormous gaps in our knowledge, the sparseness of our observations
and the superficiality of our theories” about climate.
The phrase “global warming” is misleading
because the warming caused by greenhouse gases is not evenly
distributed. In any case, the warming effect of CO2 is outweighed by
the larger greenhouse effect of water vapor.
“The warming is real,” Dyson said, “but it
is mostly making cold places warmer rather than making hot places
hotter.”
The increasing abundance of atmospheric CO2 has
physical and biological consequences.
As one of the greenhouse gases, CO2 affects the
radiation of heat energy from Earth’s surface back into space. But
CO2 is also essential for the growth of plants on land and in the
ocean and therefore important for the maintenance of the biosphere.
There are no easy, much less clear-cut, answers
to the question: which of these two effects are beneficial or
harmful?
Experiments in greenhouses have shown that the
yields of food crops are increased by roughly a square root when
exposed to abundant CO2.
A similar increase might have occurred in the
world’s production of biomass. The explosion of life for example
during the Cambrian period coincided with high levels of CO2 in the
atmosphere.
The truth is there’s very little carbon
dioxide to maintain the biomass. If the total CO2 content of the
atmosphere were converted into biomass it “would cover the surface
of the continents to a depth of less than an inch.” This is why
fossil-fuel burning is important for plant growth and animal life.
The rise of sea level is another matter that’s
not well understood. Is it due to human activities? The evidence,
Smil and Dyson say, is not convincing. Measurements of sea level,
dating back 200 years, are accurate. But man’s activities during
the Industrial Revolution in the 19th century were not enough to
account for the slow but continued rise of sea level.
There might be other causes. One of them might
be the slow readjustment to the change in the shape of the Earth
that might have begun 12,000 years ago with the disappearance of the
northern ice sheets at the end of the last ice age.
Another possible cause is the melting of
glaciers, which also began long before man’s influence on climate
became significant.
Another danger that the world faces is the
coming of a new ice age. Ice ages occur in 100,000-year cycles. A
new ice age is overdue, if it has not yet begun. Is fossil-fuel
burning making another ice age likely or unlikely? We don’t know.
Wallace Broeker argued in an article in Science
(Vol278, 1997) that warming in the Arctic due to the direction of
sea currents and to the salinity of seawater could, paradoxically,
bring on another ice age.
Since these are opposing conclusions, we have to
admit ignorance.
Computer models, however ingenious, cannot
capture in their totality the interrelationships of the biosphere.
Our understanding of the ecology of the planet is partial and
fragmented. What’s needed is an integrative science that includes
physics, chemistry, geology and biology. Climate studies are tending
towards such a convergence but has not yet attained it. In the
meantime, the matter of climate change is being framed not in
scientific but in ideological terms.
The key question is: do humans have the right to
reorganize nature or should we aim for coexistence with nature?
As Dyson put it, “the greatest evils are war
and poverty, underdevelopment and unemployment, disease and hunger,
the miseries that deprive people of opportunities and limit their
freedoms.” These are the pressing human problems that we should
face now.
The Smil/Dyson conclusion: “life is
complicated and any theory that attempts to describe its behavior in
simple terms is likely to be wrong.”
opinion@manilatimes.net
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