To the best of my knowledge, none of the current computer models can start with a known set of conditions from some point in the past, say 100 years ago, and accurate determine what our current climate turned out to be. If they can't do that, then they're useless to predict what the future will be. I've made my living as a software engineer for many years. I know that any computer model is only as good as the working understanding of the real thing. GIGO (Garbage In, Garbage Out) is the principle rule for all computer systems, especially models. You can't seem to grasp that simple, fundamental concept. Putting any faith in nonvalidated models is nothing short of foolish.

The Earth's climate is far more complicated than simple heat in, heat out. It has constantly changed over all of geologic time. Scientists are finding that seemingly simple things like clouds can have profound effects, similar to homeostasis in living organisms. Increasing temperatures cause increased evaporation, which means increased cloud cover. Low altitude clouds tend to trap heat forming a positive feedback, while high altitude clouds reflect heat from the sun causing negative feedback. This relationship was only recently proven and yet many of the climate models don’t factor in clouds at all, nor do they account for solar variability or a host of other factors that can influence climate. At today’s level of scientific understanding, the existing models are nothing more than SWAGs (Scientific Wild Ass Guesses). You may feel comfortable making economic and environmental decisions based on these half-assed models but I don’t.