The absorption of IR photons by CO2 molecules is well understood at the macro level. It's the same as with partly cloudy skies at night. As clouds go over reporting stations you can actually see the temperature stop dropping then continue when the clouds move off. Same as a greenhouse which stops convection but also absorbs and reemits heat. It's easy to test by tying a space blanket way up in a tree (so that there is no convection stopping effect) and sleeping under that versus sleeping under the stars.
At the quantum mechanical level it is considerably more complex. Photons may not be absorbed and reemitted the way we think they are.