"Bill Habr" wrote:

It doesn't matter what the other gases in the atmosphere are.

Of course it does, what are you, a confusionist?

Evaporation and condensation depend on the temperature and the pressure of water vapor.
thus evaporation and condensation are happening all the time, there is a point where
evaporation and condensation are equal.

Can you/anybody be sure how much "free" CO2 there is,
water droplets in clouds can hold a lot of CO2. Most CO2 caused
by man is at high temperature along with a lot of water vapor from
burning in the same fuel molecules.

Consider dew point and relative humidity:
Dewpoint:
The temperature to which the water vapor must be cooled at constant pressure in order for
equalization** to occur.

Humidity:
The ratio of the vapor pressure to the equalization** vapor pressure at a given
temperature with respect to water, usually expressed as a percentage.

** "equalization" is sometimes referred to as "saturation" but "saturation" is a hold over
from an 18th century understanding of science when it was thought that air was like a
liquid solution.

Maybe the early scientists talked of carbonic acid because
they were sure that dry CO2 may not even exist in nature, or even
without drying in the production of "pure" CO2.
Comments by people who provide the CO2 to industries might
shed some light on this subject and be helpful to climatologists who
want truth instead of concensus.