I discovered in 2012 introducing radiating gases like H2O and CO2 to the atmosphere actually cools the Earth slightly and had useful direct email exchanges with Singer on the matter. Naturally I am pleased he has reached a similar conclusion, perhaps by another way.
The proper way to calculate CS is from the laws of physics, chemistry, biology and chemical engineering with correct physical properties. Relying on empiricism and data regression for large complex engineering systems is well known to be incorrect and flawed. They never represent the nonlinear world outside their domain of fit; cannot extrapolate, only interpolate. Same for stock market charting. The whole data fitting exercise to support GHGT (greenhouse gas theories) is worthless from its inception. (Except it conveniently proved CO2 lags temperature by 800 years from Al Gore’s 420,000 year trend, proving CO2 could not cause these temperature changes; the sun did it.)
My way is physics, the Stefan Boltzmann Law of radiation intensity from all matter proportional to its temperature and emissivity. This Law works for entire planets, even when there are clouds, thermal feedbacks and hurricanes.
If non-radiating O2 is exchanged for absorbing/emitting CO2, emissivity, e, of planet to space must increase.
I = σ e (T/100)4
If e increases with CO2 at constant I, T goes down. Therefore CO2 causes global cooling.