Nitro, for me the most serious contradiction present in the arguments of those still holding to the Hansen AGW hypothesis is their assumption of positive feedback. I am a Ph.D. Scientist with many years of experience both carrying out and directing research, and have published many papers in the primary literature, including areas not unrelated to AGW studies. I read, many years ago now, Richard Lindzen's papers which were highly critical of Hansens Hypothesis, but for reasons entirely apart from Hansen's assumption of positive feedback . Then I did not take much further interest until the comments in this forum got me reading again some of the more recent primary literature. It is at this point that it hit home with me that, because of CO2's trace concentration and its relatively weak greenhouse gas properties, the only way such small nominal increases in concentration on the order of 100 molecules per million of air molecules could affect surface temperature in a measurable way would be for there to be positive feedback. I simply accepted, therefore, that Hansen's assumption of positive feedback must be correct. It wasn't until much later that, like a bolt out of the blue, it hit me that there is a huge contradiction in this assumption. (This must have been missed by nearly all of the other scientists as well, although eventually many came around to the idea that the observations are not consistent with the presence of positive feedback.) Here is where the contradiction arises.
If a system, such as a climate system, has any degree of positive feedback, small finite changes in input will drive the output to its extreme, whereas negative feedback will result in the systems response to a small finite change in the input being cancelled to an extent proportional to the amount of feedback. In a climate system the response of the output to a change in the input could be very slow, but in geological time it would still occur in the twinkling of an eye, so to speak. If positive feedback in response to an increase in atmospheric CO2 had been present at any time in our geological past, and the Hansen hypothesis is correct, then surface temperature would have extinguished all life. (The carbon hydrogen bond breaks at ~ 250-75 deg C.)
In a nutshell, what I am saying is that for our climate system to be stable, the feedback response to perturbations must be negative not positive. Either the assumptions for parameter values in the models are far off, so that response time to perturbations are far longer than expected, or the assumption of positive feedback is dead wrong. The present primary literature strongly suggests the latter. If I'm right, a reasonable question is how could this contradiction have been missed by so many?
I can tell from your posts that you are either a mathematician, a physicist or at least have interest in those areas. If you have studied any aspects of electrical engineering, and in particular, operational amplifiers, I think you will have no problem following my argument. I would be very much interested in your comments.