Cecil Moore wrote:
Dave Platt wrote:
One good example, I think, is the theory of continental drift -

Another is that global warming is caused by the
sun, not by Al Gore's species.

Global warming - or cooling, due to solar flux and independent of
internal mechanisms (like us) has been the mainstream knowledge for a
long, long time.

Correct.

I believe that Cecil (like a very great many other people) is falling
victim to a classic logical error, commonly referred to as "the
fallacy of the excluded middle" or "false dilemma".

In this instance, Cecil's statement carries with it an implied
assumption: that global warming (assuming that it exists) is due
*either* entirely to the effects of the sun, *or* entirely to the
effects of mankind. Cecil's statement implicitly denies the
possibility that *both* of these factors (as well as others) may in
fact be contributing to whatever warming, cooling, or other climate
change is occurring.

Taking such an exclusionist position can certainly be convenient. If
you can define the terms of the debate in this way, then all you have
to do is prove *some* truth to your own side of the argument (e.g.
demonstrate that solar changes do have effects on Earth's
temperature), and by exclusion you have "proved" the falsity of all of
your opponent's arguments and evidence. I've seen this tactic used by
those arguing both sides of the global-warming debate.

I don't believe that the real world is as simple as this. Measurable
effects can have many contributing causes. My own conclusion is that
global climate change has both external (e.g. solar and earth-orbital)
and internal (greenhouse-gas) origins, and that at least some of the
latter are heavily influenced by human activities.

As to the relative contributions of these internal and external
forcing functions to the final climate on this planet... we have to
depend on theory, modelling, and experience to figure that out.

To me, the really scary possibility is that the combined effect of
internal and external stimuli will push the system out of one
mostly-stable state, and into another, through a difficult-to-reverse
toggle point. Warming and drying up the Amazon far enough to make it
flip over from rainforest to savanna might be one such toggle.
Warming up the deep ocean enough to start melting a large quantity of
methane hydrates would be another.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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