CO2 cannot 'trap' heat! As soon as an energised molecule comes into contact with a non/less energised,  i.e. cooler one, of which there is an abundance higher in the atmosphere, it gives up/transfers that energy. It cannot hold onto it. Why do you think they use CO2 in refrigeration systems? Because it's a very good transporter of heat (absorb AND RELEASE) & not a holder of it.

Our climate is almost entirely due to the water vapor in the atmosphere and the associated water cycle, evaporation and condensation, driven by the sun. CO2 is a bit player at best. Without WV, we'd actually be a lot hotter during the day.   The vast bulk of atmospheric heat transfer is by convection, originating with conduction from the surface and ending with radiation to space. Beyond the sun's heating of the surface, radiation plays a minor role in atmospheric heat transfer. Note also that the concept of back radiation further heating the surface is bunk. Cooler cannot heat warmer.