On 22 Apr 2007 10:34:09 -0700, wrote:
On Apr 22, 10:22 am, "Larry" wrote:
On 22 Apr 2007 04:18:41 -0700, wrote:



http://en.wikipedia.org/wiki/Greenhouse_gas

In climate models an increase in atmospheric temperature caused by the
greenhouse effect due to anthropogenic gases will in turn lead to an
increase in the water vapor content of the troposphere,

It's going to be difficult for those people to explain the very real
fact that the earth has been measurably cooling for the last eight
years, in spite of an increase in CO2 levels.

I've done lots of computer modeling in my time, and I know how terribly
inaccurate computer models can be, even in the hands of trained
scientists. First of all, computers use finite sized registers (only so
many digits per number), and differential equations must be approximated
by means of various numerical techniques. Often, the modelers who write
the programs aren't really cognizant of truncation and roundoff errors
and how those errors propagate throughout their calculations. It is
quite easy to wind up with answers which are totally meaningless at the
end of several hundred million arithmetic operations, because by then
all you may have left is basically reproducible digital noise. It isn't
enough to have a good mathematical model and good data when you start.
You must also have an experienced numerical analyst examine and test
your computer algorithms if you want to have any chance of avoiding
digital oblivion. The algorithms must be completely tested with data
that give a known answer before they can be used for anything else.

Most atmospheric scientists are lousy numerical analysts. Most
numerical analysts are lousy atmospheric scientists. Guess what you are
likely to get when you use either individual by himself to produce a
computer model?

The modeling aside, it always makes me suspicious when someone invokes
what amounts to an unstable equilibrium argument (a tipping point) to
explain how a minority variable (CO2) can drastically influence the 95%
majority greenhouse gas that is H2O. It's akin to arguing that the
atmosphere is like a coin which has been carefully put down on its edge
and which therefore only needs a slight shove to make it fall over.
Nature constantly applies perturbations to the atmospheric system, and
if it were that unstable, it would long ago have "tipped."

The Wikipedia statement looks very much to me like rationalization. The
writer is already invested in the idea that CO2 somehow is the key, and
so he invents an argument to make things come out that way. That's not
science; that's hand waving. Note that he apparently can't attach
numbers or observations to the argument he has made.

But there may be a resolution: According to one group of scientists
which tracks solar irradiance, the observed cooling of the earth is
going to accelerate. They claim that the earth will be significantly
cooler than it is today by 2040. If that even comes partially true,
then we will know that the CO2 advocates have been quite wrong.

Stay tuned.