On Tue, 28 Dec 2004 10:11:13 -0700 Big Bill wrote:

All this is true.
However, the fact remains that we simply don't *know* what's causing
the hole. We can model a change, but we still can't say for sure that
the model reflects reality. We can only say the model reflects a
*possible* reality.

If I understand you correctly, you are saying that theory is nice, but
it isn't convincing until you have an observation that proves it.
Certainly yours would be the most convincing senario, but I wonder if
you are willing to be consistent with this attitude.

Take natural radiation, do you feel that spontaneous fission is an
unproven theory just because no one has ever actually been watching a
particular atom when it broke up?

Do you believe in electrons? Have you ever seen one? Has anyone?

Relativity predicts that my yardstick will look 18" long to you if I
pass you at a significant fraction of the speed of light. Do you
choose to postpone your belief until this particular experiment is
done?

How do you feel about E-M waves? Ever seen one? Maxwell's equations
make a lot of predictions which we can verify, but we still can't
actually see a radio wave.

Or how about the politically dangerous ground of evolution? No one has
ever actually watched while one species evolve into another. There's
plenty of other evidence, but again we find the scientific community
united in favor, while some non-science people argue against it.

Each of these items is something which has been explained by some
theory to most people's satisfaction, and yet none of these particular
things has ever actually been directly observed. In spite of a lack of
direct observational data, there is enough corroborating evidence that
most of us believe that we understand these things and believe the
theory to be correct.

I agree that the natural occuring variation fuzzes up the cause of the
observed ozone hole, but the science is clear that ozone depletion is
an expected consequence of chlorofluorocarbons in the atmsophere. The
observed rate of depletion is consistent with the predictions. There
IS some undertainty in the predictions, simply because very small
changes in the reaction rates have large consequences over 100 years.

I still suggest that you look around and see who is still arguing
about this topic. I don't think you will find any disagreement within
the scientific community. The objections are all political. While the
scientists are certainly willing to continue to take data forever, the
actual problem is a social one and the only solution will have to be a
political one.

Right now, the easy way out is to just say that we don't have enough
data and leave it at that. Unfortunately, or fortunately, depending on
your point of view, this can go on forever.

The real problem with waiting is that the time constants of ozone
depletion are so long that it may already be too late to do anything
about it. Even if we stopped all of these emissions right now, ozone
depletion will continue over the next 100 years. The rate of depletion
will still slowly increase for 20-50 years as Freon from the lower
atmosphere slowly diffuses upwards and only later will the rate of
depletion start to decline.

None of the living things on this planet have evolved to cope with the
amount of UV that they might be exposed to. Sure, we can all wear
hats, but what if our wheat won't grow in this environment? Fish can
hide in the deep water, but what will they eat? What will we breathe
if our green plants don't survive?

Alarmist? Sure, but not too unrealistic. We're all interdependent in
ways that most of us don't comprehend, and it might just be a little
change like this which would push us all over the edge, not with a
bang, but a wimper.

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Jim Adney
Madison, WI 53711 USA
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