You're jumping ahead. I'm not intending to make an argument about cloud cover.
CO2 does not have any effect on the reflectivity of the earth.
I disagree with your statement here. CO2 has very little effect on the reflectivity of the earth in the visible spectrum. But we need to consider the full spectrum of solar radiation.
Does a greenhouse gas like CO2 absorb more infrared radiation than say N2? Does the Sun emit radiation in the infrared band?
The moon has very little relevance to this discussion. We aren't talking about Earth with no atmosphere vs Earth with atmosphere. We are talking about Earth with one atmosphere vs Earth with an atmosphere with a difference composition.
