WILL TOMORROW'S CLIMATE BE?
November 25, 2002
Predictions can drive our actions, depending on their reliability and
their consequences. Thus, although presumably reliable, a prediction
by astronomers that two black holes will collide in space a distance
of 400 million light years from Earth should not determine what you
buy at the grocery store next week. On the other hand, an ice storm
next week could significantly affect your plans. But the past record
of local weather predictions in most regions is so dismal who would
put together Saturday's shopping list based on Monday's ten o'clock
So how should we respond to predictions of changes in climate, the average
long?term weather conditions in a region that could potentially have
major consequences on our lives? I think we should heed the warnings
promulgated by eminent scientists.
One practical reason for developing predictive models of Earth's changes
hinges on concern for such phenomena as global warming and depletion
of the ozone layer. For example, according to reputable sources, concentrations
of gases in the atmosphere, namely chlorofluorocarbons (CFCs), the coolants
used in air conditioning, have increased measurably since the 1950s.
Continued overuse was predicted to cause further destruction of the
Likewise, dire predictions of global warming from some scientists have
been based on measurements of increases in carbon dioxide and methane,
"greenhouse gases," that end up as a shroud around the earth.
Whether governments pay attention to and take action based on these
predictions could determine how livable the world will be in the future.
Scientists trying to predict climate base their calculations on past
climatic conditions. Several techniques have been developed to establish
associations between cosmic conditions and the earth's atmospheric state.
In addition, relationships have been established between global conditions
and the presence of glaciers, the temperatures of tropical seas, and
the advent of humans. One technique measures trace gases that were in
the atmosphere up to 150,000 years ago by examining deep layers of polar
ice formed centuries ago. The age of the ice layers is estimated based
on known rates of deposition. Using complex procedures, scientists can
measure gas levels in air bubbles trapped in polar ice. The trapped
air presumably represents a sample from earlier times in Earth's history.
According to some findings using this technique, carbon dioxide and
methane have increased steadily since 1750, roughly the beginning of
the Industrial Revolution when power?driven machinery and factories
began to be common. Thus the abrupt rise in levels of carbon dioxide
and methane is attributed to humans and, as stated in one report, "support
the prediction of a significant greenhouse warming [effect] for the
Another method for gauging past climates and therefore more effectively
predicting future ones is to relate periods of high and low temperatures
to cosmic and geologic patterns. The earth's climatic history has presumably
been greatly influenced by variations in the earth's orbit and orientation
toward the sun that appear cyclical. The earth today is closest to the
sun in January (winter in the Northern Hemisphere because of the tilt
of the axis) and farthest away in June. But studies of celestial movement
patterns indicate that 11,000 years ago the opposite was true, the consequence
being colder winters and hotter summers. Can subtle celestial changes
be predicted for the not?too?distant future that might result in more
than subtle climatic effects?
The world's climates are not static. Glaciers once covered what is now
the upper portion of the United States. Oceans once covered land where
forests and cities now thrive. Even the world's carbon dioxide levels
have been both higher and lower than today, although uncertainty exists
about the true amounts.
According to some estimates, carbon dioxide levels 400 million years
ago were as much as ten times higher than those today. So why worry
about global warming? Well, consider this? Has the earth ever before
experienced such abrupt and rapid increases in carbon dioxide? If so,
then dramatic fluctuations may be within the realm of natural responses.
If not, we should perhaps be a bit concerned.
If climates begin to change in our lifetimes, we will have worries of
a different magnitude. Maybe we should forget about weather reports
we cannot affect and pay more attention to climate forecasts that we
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