Some people, including the infamous Dr. Happer say that CO2 cannot radiate due to a plethora of molecular collisions that abort almost all of the ability to radiate15 micron photons. Why are they wrong?
The short answer:
A molecule vibrating in the15 micron radiation mode can hold that energy...
One common argument against CO2 having any effect on the climate is that it is such a small quantity - only 400 parts per million. It is small compared to the full atmosphere, but how does it compare with the largest green house gas, water.
Water in the Atmosphere, the Water Cycle, from USGS...