T8 wrote:
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.
If this explanation made sense, we'd be as hot as Venus; in fact, heat
does work it's way up to the top of the atmosphere, and radiate into
space. It is up there, where the heat is actually escaping the planet,
that the concentration of CO2 is important, and the concentration of
water vapor is very low by comparison. Increasing the CO2 in the upper
levels of the atmosphere does significantly effect how easily heat
leaves the planet. This site has a pretty good explanation:

http://skepticalscience.com/link_to_...?Argument0=133

--
Eric Greenwell - Washington State, USA
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