tin, I don't see how you can validate a model where you don't know the major component of it. I'm referring to water vapour, which is between 5 and 10 times the greenhouse gas that CO2 is. We measure the CO2 concentrations to 5 sp but don't know the amount of water vapour in the atmosphere to within 2% of the total atmosphere (estimates vary between 2% and 4% of the atmosphere, a variation of 100%).
Saying that there is a model which predicts that if CO2 increases by 20% then it will cause such and such an effect are nonsense, when the model can't tell you how much water is involved ......
