Radiation from the planet is nearly all in the range 6-100 microns. CO2 absorbs/emits only at 15 microns (at sea level, pressure etc. broadens this to approximately 13-17 microns).
At sea level, it takes 10 microseconds for a CO2 molecule to emit a photon after it absorbs one but only about 0.0001 microseconds to thermalize the energy that the photon contained so thermalization prevails.
Water vapor has more than 400 absorption lines (absorption opportunities) per molecule in the range of terrestrial EMR compared to only one per molecule for CO2. Also, there are on average approximately 15,000 ppmv water vapor compared to the 100 ppmv or so increase in CO2. Thus the increase in CO2 has increased absorption
opportunities by only 1 in about 60,000.
Search “agwunveiled” to find out how this is part of the explanation of why CO2 change has no significant effect on climate change. Also, discover the identity of the two natural drivers that do, with 95% correlation since before 1900.