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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