Basic Science: Climate Sensitivity Less Than 0.3 C

For the convenience of the reader I here collect the links to a couple of basic arguments showing that the effect of doubled atmospheric CO2 at most could be a global warming of harmless 0.3 C, that is that the climate sensitivity is smaller than 0.3 C.

The idea is to combine observation with simple mathematical models, where observation is used to determine the coefficients of the model, thus allowing prediction. Stefan-Boltzmann's radiation law for an ideal blackbody is not used, since it does not describe the complex Earth-atmosphere system.

I thus only use simple models with coefficients determined by observation, which is the basic scientific method leading to the basic mathematical models of physics, such as the heat equation, potential flow equation and radiative transfer equation.

I assume that doubled CO2 could correspond to a change of the radiative properties of the atmosphere of 1%, or a "radiative forcing" of 3 W/m2 = 1% of a total insolation of about 300 W/m2.

I assume that the "atmospheric effect" is 33 C corresponding to raising the temperature of an Earth without atmosphere (= observed mean temperature of the Moon) of - 18 C to the observed temperature of the Earth with atmosphere of 15 C.

• 1 % of the atmospheric effect 0f 33 C = 0.3 C.
• Combination of thermodynamics and radiation = 0.3 C
• Diurnal temperature variation (amplitude and phase lag): 0.3 C .

These are three different arguments using different data and different simple models, all giving the same result of a climate sensitivity smaller than 0.3 C, where 0.3 C is to be viewed as an upper bound, with the real value probably a factor 2 - 3 smaller.

IPCC claims a "best estimate" which is 10 times bigger = 3 C, which is obtained by confusing definition with physical fact and free invention of positive feed-backs.

IPCC has invented a factor 10 for which there is no scientific basis. In economics a factor 10 would be swindle and it is the same in science, or even worse.