Every IR photon with the right wavelength to be absorbed (I forgot that caveat). There are something like 10^25 molecules in a cubic meter of air or 10^22 CO2 molecules. That is more than enough for absorption saturation. But of course those molecules also radiate in all directions including out to space. So each layer of the atmosphere also cools more as it gets warmer.
Even if it were possible, a warming atmosphere would produce more water vapour in clouds causing cooling of atmosphere once again
If the surface is wet. That's the reason the southern hemisphere has warmed a lot less than the northern overall.
But one other important fact often glossed over is that CO2 comprises a tiny 0.4% of all the gases above our heads
From above, 10^22 molecules of CO2 per cubic meter cannot be ignored.
Please don't point to Postma and other junk as "debunking" the greenhouse effect. Basically Postma is attempting to "prove" through his equations that the surface warmth can be explained without GHE. But he makes several mistakes and the alternative, that GHE is required to reach current average temperature, is accepted science. There are many threads at Curry's and other places explaining this: http://judithcurry.com/2011/08/16/postma-on-the-greenhouse-effect/ Suggesting that Curry has abandoned the GHE effect just because she doesn't like the phrase "back radiation" is incorrect. All sides in that "debate" agree that the atmosphere absorbs some IR. The only actual disagreement is whether back radiation is a "real" transfer of energy via IR photons or not. But if the CO2 in the atmosphere absorbs IR, it also radiates IR in all directions.
[[But if the CO2 in the atmosphere absorbs IR, it also radiates IR in all directions.]]
I guess you’re issing my point- such a small amount of CO2 is not nearly enough to absorb all the heat moving out toward space- it is only to absorb a very small amount- there are vast swaths of atmosphere where there is no co2- and only a very tiny fraction of our atmosphere that has co2- and as you point out even that tiny fraction of absorbed heat gets radiated out in all different directions, so even less makes it back towards the earth, and even then that insignificant amount cools as it approaches the earth-
[[But he makes several mistakes and the alternative]]
Which would be what mistakes?
[[From above, 10^22 molecules of CO2 per cubic meter cannot be ignored.]]
How many actual molecules per CM are there total? 10 to the 22 sounds like a lot, but what are the actual total CM molecules? if 10 to the 22 is still only 0.04%, then the amount of actual over all molecules must be enormous and the 10 to the 22 is very insignificant compared to the amou8nt of total molecules- the poinjt being that the tiny fraction of CO2 will become saturated very quickly, and any remaining heat blows on past the tiny fraction of saturated CO2 because it can’t absorb anymore- and again- as you point out, that tiny fraction of CO2 radiates in all directions
it would seem to me, that of all the heat escaping toward the atmosphere, only 0.04% of it is going to be trapped and of that small amou8nt, only a very tiny fraction is actually going to be radiated back towards the earth, and even then, it’;s goi9gn to be cooled as it makes it’s way back towards the earth- the heat ools in both directions, as it rises, and as it radiates back- it’s seems impossible that such a small amount of heat making it’s way back towards the earth to cause the whole globes climate to change-