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Just how likely is it that increasing levels of carbon dioxide
resulting from human use of fossil fuels will cause a significant
increase in global temperature — and that such an increase will be
seriously harmful to human society? You may have the impression from
the media and Al Gore that this awful scenario is a scientific certitude
unless we “take action” to prevent it.

A survey of what reputable scientists are actually saying on the
question, however, suggests that it is quite likely that no one on earth
knows just “how likely” these bad results are. In fact, I think it is
quite unreasonable for anyone to be confident that we face a
human-induced global warming that will, on balance, be harmful rather
than beneficial for humanity or the environment, much less that such a
warming would be catastrophic.

First, what is the basis for the scientific claim that global warming
is under way as the result of the real increases in atmospheric carbon
dioxide that have been measured over the past century and more? As Dr.
S. Baliunas of the Harvard-Smithsonian Center for Astrophysics points
out, most such predictions are based on computer simulations of the
climate.

Have you ever stopped to think how difficult it would be to develop a
set of rules that would describe the behavior of the global climate over
a century or more? Would this task be more or less difficult than
developing rules that would accurately predict the weather in your
hometown a week from now? Here are just some of the difficulties that
the computer models face.

It is always difficult to describe the real world in terms of a set
of rigid rules, but this is particularly true when attempting to
describe a situation with many causes that act and react upon each
other. The global climate is, to put it mildly, one of the more
complicated systems that scientists attempt to model. Very roughly
speaking, for each causal factor in the real world, a quantitative rule
of behavior is added to the model which describes its effect on each of
the other factors involved. The possible combinations of such causes
and effects multiply dizzyingly. Dr. Baliunas and her colleagues have
noted that a sophisticated computer model of such climate parameters and
their interactions would have to track millions of distinct
cause-and-effect relationships. Computers do not even exist today that
are powerful enough to handle the calculations that would be required.
In addition, very slight differences in the original situation or the
rules governing the model can lead to widely differing model results.
The longer into the future the model is run, the more widely its results
can vary from those of another model which expressed its rules slightly
differently.

Imagine trying to calculate the path of a ball rolling down a rocky
hill. Now imagine trying to calculate global weather patterns a century
in advance!

It is important to note that the difficulty of modeling the global
climate system does not result merely from the enormous complexity of
the system, but also from the fact that the physical processes
themselves are incompletely understood. For example, depending on their
height, clouds can exert a warming or cooling influence on the
atmosphere. Yet, the formation and behavior of clouds remains somewhat
mysterious.

The “greenhouse” effect of carbon dioxide in isolation from all other
factors is fairly simple to calculate, while the actual result of
increased carbon dioxide in dynamic interaction with all the other
factors in the earth’s climate is dauntingly complex. Is it any wonder
that models constructed by advocates of the global warming theory would
have tended to overemphasize the warming effect of carbon dioxide? Or
that the warming predicted by their models for the period of the most
rapid increase in atmospheric carbon dioxide has continually exceeded
the actual recorded warming by significant amounts? In models, it is
sometimes easy for a scientist to find what he is looking for — after
all, he is in some respects the creator of the world he is studying.

Connected with the difficulty in understanding the effect of carbon
dioxide in climate change is the fact that other factors are known to
affect global climate — above all, the sun. In the rush to a spurious
scientific consensus that human production of carbon dioxide threatened
the earth, the possibility that the principal cause of global
temperature change is the sun’s varying output of energy was dismissed
as “junk science.” Now it begins to look as if the sun is an important
cause of the modest warming that has in fact occurred over the past 150
years. The Sunday Times of London reported over the weekend that new
research, based on data provided by the European Space Agency, is to be
released this week at one of the first conferences bringing solar
researchers together with scientists investigating global temperature.
The Times reports that the new research shows that “earlier computer
models severely underestimated the sun’s impact” on global temperature
– and that global warming “is caused mainly by the sun.”

Whether or not the study is as reported, the scientific community is
beginning to take seriously the possibility that the sun plays a major
role in climate change. And what happens if scientists find that the
sun is responsible for much or even most of the modest warming the world
seems to have experienced during the past century? Partisans of
coercive energy conservation schemes like the Kyoto protocol might find
this very inconvenient. For how in the world would we legislate
reductions on solar emission?

Perhaps more important than assigning responsibility for global
temperature change in the years ahead is the question of whether such
change will help or hinder human life. Is a slightly warmer atmosphere
– whether caused by man or by the sun — such a bad thing? There is good
reason to conclude that we have little to fear, and perhaps much to
gain, whether we or the sun is the cause of warming. In Senate
testimony last month Robert Mendelsohn, Yale Professor of Forest Policy,
reported that his ongoing research indicates that currently predicted
levels of warming by 2100 are likely, on balance, to provide economic
benefits in the Unites States of between 14 and 23 billion dollars per
year. He noted that the critical factor in these predictions, which
represent a modification of earlier predictions of significant cost from
warming, is that “adaptation matters.” That is, “Empirical research
indicates that households and firms will respond to climate change and
reduce damages and enhance benefits.”

Perhaps the most important potential effect of the undeniable
increase in carbon dioxide will be its dramatic enhancement of the
productivity of farming. Carbon dioxide is the most important plant
food and a significant increase in the levels of atmospheric carbon
dioxide is very likely to be an important enabler of a second Green
Revolution, as Drs. Keith and Craig Idso of the Center for the Study of
Carbon Dioxide and Global Change have argued. Elevation of carbon
dioxide may be, in effect, a global, equitable and un-bureaucratic
nutritional program for the world, with proportionally greater effect in
precisely those areas that now suffer most from low agricultural
productivity.

Breathless predictions of melting icecaps, rising oceans, inundated
coastlines and super-storms around the world, meanwhile, look
increasingly unfounded. If the models were correct, we should already
be well along toward such dangers and they are simply not occurring.
This might be partly explained by the failure of the earth to warm as
rapidly as the models have predicted, but then this means that the
models may well continue to overstate the warming we face. Even
predictions of the increased spread of malaria and other infectious
diseases turn out to be based on simplistic assumptions that temperature
is the dominant factor in their spread. But this is simply false; as
Dr. Paul Reiter of the Centers for Disease Control points out, the
United States is largely free of such diseases because of its systems of
hygiene and health, not its temperature, and the coldest centuries of
the past millennium were some of the most afflicted with these same
diseases.

The scientific debate surrounding global temperature change and human
generation of carbon dioxide is vast. The citizen’s duty is not mastery
of a difficult and complicated scientific literature, but a general
supervision of the use society makes of the claims of science, including
the insistence that political agendas posing as science be filtered out.
In the case of global warming, it is clear enough that much of the
supposed science of the past decade has actually been political activism
by other means. Perhaps the tide is turning now, but it is still
important that — in the face of ongoing alarmism and fear mongering –
we spread the word that the issue of global warming is much more
complicated, and much less alarming, than the gashouse gang has let on.

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