(06-19-2019, 09:21 AM)MalabarJag Wrote:

(06-19-2019, 06:57 AM)mikesez Wrote: the amount of heat that CO2 absorbs rises linearly with the concentration of CO2.

The temperature of the atmosphere rises linearly with the amount of heat it absorbs.

However, the tendency of water molecules to be in vapor form (the vapor form is invisible to the human eye and absorbs solar radiation, while clouds are liquid water and reflect it) rises exponentially with increasing temperature. Consult an ASHRAE manual, look up the Buck equations... or, hey, don't. You do you.  The ASHRAE manuals could have been written to help design air conditioning systems, or they could be part of a vast conspiracy to help scientists topple limited governments and institute their form of communism. Next time you enjoy an air-conditioned or heated interior space, you can smugly think to yourself how much better it would work if the designers were using real math instead of conspiracy math.

More water vapor in the atmosphere results in more clouds. 

Clouds only form when the air is at saturation.
The saturation pressure of water vapor increases exponentially with temperature.
Therefore, the number of water vapor molecules that need to be in the atmosphere prior to cloud formation increases exponentially as temperature increases.
Clouds will still form.
A slight increase in temperature for any layer of the atmosphere exponentially increases the amount of water vapor that will exist in that layer immediately prior to cloud formation.
The amount of incoming solar radiation that is trapped in the atmosphere immediately prior to cloud formation therefore exponentially increases as the local temperature within that layer of the atmosphere increases.

You're right that the concentration of CO2 in the atmosphere is already sufficient for the atmosphere to absorb 100% of solar radiation at a few wavelengths. But not all of them.  Specifically, at about 1.5  to 2 micrometers wavelength, our atmosphere is still transmitting rather than absorbing most solar radiation.  But increasing CO2 concentration will change that, until 100% of that radiation is captured.

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