`  Sigh. The model used by R+S in 1971 is very primitive; its not a GCM, its a 1-d RC model. It was ``refuted`` a long time ago. In fact its self-refuting: as they say in the paper, the model is only suitable for studying small perturbations, but they use it for large ones. I recommend reading note 3 to the article. As everyone has pointd out to you, the logarithmic nature is well known; its in all the current GCMs; the results you refuse to believe incorporate it; it is not in dispute  `