Lately, we have all been talking
about the greenhouse effect. This effect relates to the expected warming of our
planet resulting from changes to the composition of our atmosphere. There is
mounting evidence that our own activities, most significantly the burning of
fossil fuels, are a major contributor to this effect. The predicted
consequences are quite sever, including major changes in climate which will
have impact on food production, and rising sea levels which will submerge coastal
and other low lying communities.
Lurking in the background
hauntingly are the facts we have discovered about our near neighbor, the planet
Venus. Because of its dense atmospheric gases, Venus has what has been
described as having a runaway greenhouse effect, giving surface temperatures of
about 8000F. Now I love the warm summer weather, but that is a
little too hot for me.
The usual villains in the
greenhouse scenario are gases such as carbon dioxide. Carbon dioxide, which,
incidentally, we all exhale, has the unusual habit of absorbing infra-red
radiation. Infra-red radiation for those of you less scientifically minded is
actually heat radiating away from a warm object. During the day, sunlight warms
the earth and during the night the Earth cools by radiating heat into space in
the form of infra-red radiation. Carbon dioxide, and to a lesser extent other
gases, absorb this radiation, limiting its exit out into space, and thus
limiting the natural cooling effect.
Would it be safer if we had no
greenhouse effect at all? Well, no, we do
not want that either. There is another
member of the heat absorbing clan. This is water vapor. There is a large amount
of water vapor in the atmosphere at any time, which is why we have rain. The
presence of water vapor as a heart absorbing gas keeps the Earth comfortably
warm. Without this warmth, the planet would freeze, and life as we know it
would not be possible. We therefore do need some greenhouse effect, just not
too much.
Mother Nature is again telling us
what we should already know; in any situation, both of the extremes are
harmful.
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