Bart, this is a great example of what I call AGW thinking. It invokes equilibrium conditions when the actual climate is a far from equilibrium system. It also refers to the 1000 year temperature record as though there were such a thing. We don’t even have a 100 year temperature record. Nobody has been recording the global temperature, not until the satellites were launched in 1978, if then.
Regarding sensitivity, consider the very real possibility that the evidenced (not recorded) temperature oscillations are due to chaotic feedbacks. Chaotic systems oscillate with constant forcing. In that case if the sensitivity were defined as the temperature change divided by the forcing change then the sensitivity would be infinite.
Simply put you are invoking physics that is not applicable. That is the essence of AGW. There is no equilibrium based sensitivity, because the system in question is not an equilibrium system. I don’t use the “f” word (fraud) but if I did this would be where I would use it, for invoking conditions that are known not to hold.