The perturbation in CO2 concentration in the atmosphere is obviously well outside the range of what has happend to atmospheric CO2 concentrations since the end of the last glacial period.
And I never see global warmers talking about posible negative feedback systems that is possibly damping the temperature response. If this is true, it is silly to talk about the exponential growth in temperature that global alarmists keep warning us about.
The chief unknown -- and still hard to figure out -- is cloud feedbacks. If warming increases clouds sufficiently, the extra cloud cover would counteract the warming influence. Most "global warmers" will mention that. As for that exponential growth in temperature, I've only seen that in the high-end predictions from models in which some of the negative feedbacks have been removed or modified. It gives the predictions an error range, and the media loves the high end, but because it's the high end it's not as likely as the mid-range, and far less likely than the low end predictions.
Oh puh_leeez cogitator. Their models are crap and they know it. They may be the based on the best knowledge of today and using the most powerful computers, but they are still in the infantile stage of understanding global climates. I would bet my life savings, which is substantial, that we will be at the lower end of the predictions or lower. Their midrange numbers and high numbers are pure whackology.