The leaked Second Order Draft IPCC AR5 essentially repeats the AR4 estimate of a climate sensitivity of 3 C:
- Equilibrium climate sensitivity is likely in the range 2°C–4.5°C, and very likely above 1.5°C. The most likely value is near 3°C. Equilibrium climate sensitivity greater than about 6°C–7°C is very unlikely.
- Earth surface temperature: + 15 C
- top of the atmosphere TOA temperature: - 18 C at 5 km altitude
- lapse rate: 6.5 C/km
- dry adiabatic lapse rate: 10 C/km
- transported from surface to TOA by thermodynamics: 120 W/m2
- transported from surface to TOA by radiation: 60 W/m2.
- 1/3 x 0.5 - 2/3 x 0.15 = 1/6 - 1/10 = 5/30 - 3/30 = 2/30 = 1/15 Cm^2/W.
An alarm of 3 C would thus be replaced by a harmless 0.3 C, which could never be noticed.
Do you say that the above argument is simplistic? Yes, it is, but it may well be more realistic than the IPCC argument leading to a climate sensitivity probably inflated by a factor 10.
In business a value inflated by a factor 10, would be viewed as fraudulent.