I have a question to do with this graphic and the CO2 absorption band highlighted with a red vertical line.
The image shows that nearly 100% of the IR energy in that band is absorbed in the atmosphere by CO$_2$ + H$_2$O. So there is very little of that "light" getting out.
If this is so, then how could adding more CO$_2$ impact much of the situation?
GHG theory suggests that adding more CO$_2$ to the atmosphere will increase the temperature, but how when the atmosphere is already trapping as much as it can in the bands that CO2 absorbs? There must be more to the story.