the combustion of coal might get us to CO2 levels from 0.036% of the atmosphere to 0.039% of the atmosphere by 2100, which can be rounded to approximately 0.0%. Which is pretty amazing since 70% of the planet is covered by water, and if you’ve ever flown across just this country at night (especially the west) it seems that most of the landmass even here is uninhabited, below a sky that is 62 miles thick. I just hope we never approach the CO2 content of the atmosphere, which was present for thousands of years into the last ice age, lest we will be in real trouble.
If compressed to sea level pressure, the atmosphere is about 5 miles thick. If compressed to the density of water, it’s about thirty feet thick. 0.036% of thirty feet is about 0.01 feet of atmosphere at 1 g/cc. CO2 is heavier than O2 and N2, but call it a wash. We’ve got an inch of CO2 at 1 g/cc. This is less than a half inch of solid carbon out of your 62 miles of atmosphere.
The CO2 concentration has risen from 0.031% to 0.039% since 1960, and this squares plausibly with the amount of carbon combusted from human activity in that time period, so to me, this puts us on the board.
Nitrogen and oxygen don’t absorb IR radiation.