Question about CO2 Saturation?

Dana's link is probably correct that saturation cannot ume equal densisty and obviously less dense gas might require more concentration to provide saturation. That still doesn't mean that increasing CO2 won't have decreasing effect. It should. CO2 has never been shown to drive temperature. Temperature drives CO2. Those are the scientific facts. You will notice that the link Dana provides doesn't say how much increasing CO2 concentration will warm the upper atmosphere or the effect this will have on the lower atmosphere. They didn't say it (or at least I don't remember reading it (I read it yesterday)) because they simply don't know.