Actually, governor is a better term than insulator. Adding CO2 would raise the average radiant layer, that is insulation. Then changing available energy would also raise (lower) the average radiant layer. Since the relative velocity of the upper troposphere changes with altitude with respect to the lower layers, this “governs” the rate of heat loss. In order for CO2 to increase the average surface temperature it would have to increase the average temperature of the troposphere above the average radiant layer. Since that layer is in chaotic motion with vorticies and jet stream wandering, CO2 cannot “charge” the upper troposphere as required to obtain the full estimated climate forcing.
Kinda makes the modeling a bit complicated.
Then you toss in the changing atmospheric chemistry with water vapor reacting with ozone and that reacting with CO2 and the other trace gases in a region with various photon energies, electron flow and magnetic flux, things can get weird in a hurry. Ever wonder why the Antarctic CO2 concentration is lower and more stable than the rest of the atmosphere? Might have something to do with the magnetic “true” north pole being in the Antarctic.