On Jan 9, 6:56*am, Tom Gardner wrote:
On Jan 9, 9:27*am, delboy wrote:

Have we actually proved
that CO2 is a greenhouse gas anyway,

Yes, of course it has been proven. If you can't accept
that then there is never going to be the basis of any
form of useful discussion.


Of course CO2 is a selective IR filter. That's basic physics.

The more interesting question is: what is the effect of changing the
atmospheric CO2 concentration?

Most of the IR absorption spectrum of CO2 is so strong that at these
wavelengths, the little CO2 in the atmosphere is optically dense, and
increasing (or decreasing) its concentration has only tertiary and
probably unmeasurable effects on climate. There are weaker absorption
bands that may make a difference, but some/most(?) of these are in
areas of the spectrum where water vapor dominates completely as long
as water vapor is present.

"Of course it has been proven"? Well, yes, the agenda setters take
that view. It's regarded as a weak point of the AGW thesis by some.
It's an area that I think deserves particularly careful study, as this
is *the* key to the "A" in AGW.

-Evan Ludeman / T8