- The spectral portions show only the emissions from water vapour and CO2when it is present. Consider the emission when CO2 is absent and assume that the global mean temperature is 280 K (7°C). The radiance to space is estimated to be 286.2 W/m2, considerably greater than the value required for radiative balance (235 W/m2).
- Adding just 1 ppmv of CO2produces a noticeable effect and the Q branch of the spectrum is particularly obvious. The estimated radiance to space is 281.7 W/m2, a reduction of 4.5 W/m2. Such an atmosphere would be radiating less energy to space and the system as a whole would be warmer. Even 1 ppmv of CO2has a warming effect!
It is also remarkable that virtually nobody seems to be willing to question the evidence of GHE supplied by Modtran, as if Modtran cannot be questioned. Maybe it is like Coca Cola,which with its secret recipe cannot be questioned.