On Wed, Apr 22, 2009 at 10:35:09PM +0900, Phlip wrote:
hurricane in the Atlantic, even if you did know how its wings flapped in
microscopic detail.
Climate is an emergent property of weather trends. Climate is an
average
of a chaotic nonlinear system.
. . . and while you may not be able to predict such a hurricane with
100%
accuracy (there’s some question about the predictability of anything in
the universe, thanks to quantum probability effects), you can certainly
get close enough for government work if you know the starting state of
all contributing factors and have time and processing power to build the
model. This, of course, ignores the possibility of free will having
unexpected influence, but I don’t think butterfly wings conform to the
definition of “free will”, so that’s not really the point here.
The problem, as Eleanor pointed out, is that climatologists’ models are
nowhere near that level of precision and comprehensiveness. The state
of the art of climate modeling is something more like witchcraft, or
horse race betting at best, at this point. Maybe in a hundred years
we’ll have achieved all the accuracy of card counting at the blackjack
tables in Las Vegas.
However, you can predict trends over time, and you can predict the effect
of forcing (such as more sunspots, or more CO2) on those trends. For
example, Katrina occurred at the peak of a decadal cycle in hurricane
activity. That doesn’t mean CO2 didn’t have a role…
You can make predictions about trends over time – but the less starting
state data you have at your fingertips, the less those predictions will
actually tend to accurately represent what will happen.
Instead researchers take patchy historical data over a brief
geological period and feed that into incredibly complex climate models
to produce predictions.
That’s the prediction phase of the experiment. Then they confirm their
predictions by correlating them to historical data, such as ice cores in
glaciers containing the predicted amounts of certain chemicals at certain
depths.
I wonder how many climatologists haven’t figured out yet that
correlation
doesn’t strictly imply causation.
predict, over time, where Mars and Jupiter would appear in the skies.
That’s as old as Astrology.
The publication of an alternate view that effectively debunked the
preceding view was, in effect, a demonstration that Ptolemy’s model
was
a load of hooey.
It’s true, though, that Ptolemy’s model didn’t “prevent” astronomy from
progressing. It just significantly hindered such progress.
