HK at 03:06 AM on 17 February, 2014
The absorption band of CO2 centred at 667 cm-1 (15 microns) grows wider as higher concentrations of CO2 make the atmosphere opaque at frequencies where it previously was quite transparent. This moves the altitude of heat loss in the “wings” of the CO2 band from the low or middle troposphere up to the cold tropopause while the central part of the band moves to the warmer stratosphere.
These spectra (made with MODTRAN) haven’t taken into account the rising surface temperature, the higher tropopause and the cooling stratosphere caused by more CO2. The latter will partly offset the growing spike in the middle of the absorption band and thus restrict the heat loss to space even more than shown here.
The impact from CO2 is very far from saturated!How we know the greenhouse effect isn’t saturated