One thing I have never understood about CO2 as a greenhouse gas is why it supposedly works only in one direction like a gaseous diode.
For example if it reflects the heat rising from the Earth back into the atmosphere, surely it does likewise with the heat from the sun, so wouldn't there would be less heat penetrating the atmosphere than otherwise? Thus balancing the equation.
I think the theory is that CO2 is largely transparent to visible light, but absorbs infra-red.
So, light arriving from the sun goes straight through it and warms the earth's surface. The warm surface radiates heat (i.e. infra-red radiation, the old black-body radiation thing). If there's more CO2 in the atmosphere then more of it gets absorbed, warming the air, rather than being radiated out into space.
On the other hand, I imagine the warmer CO2 at the upper levels of the atmosphere will now radiate more heat out into space itself. Could all get quite complicated quite quickly.