a lot of people say that there is no (or a very weak) connection between the amount of CO2 in the atmosphere and the heat on the earth. if someone were to be able to show that there is a significant amount of heat being reflected back by CO2 molecules, then this argument would be less believable.

my question is, is there a way to show this? i can imagine one such way: an FT-IR should show a band (or two) that is characteristic for CO2 molecules if one were to point its detector up towards the atmosphere (away from the sun of course). this band should be relatively compact and should be easily separated from other components of IR radiation and most importantly, should become more or less intense based on the partial pressure of CO2 in the air above it. if a significant portion of the IR radiation comes back in that particular band of wavelengths, then this should be a concern that CO2 is a large contributor to atmospheric warming.

thoughts?