The theory of AGW is based on climate modelling. Climate modelling is a brand new science with a very short heritage and very little experimental verification. It is silly to say that climate modelling is derived from "accepted principles", as if it were borne from first principles.<p>All modern climate "models" are horrible hacks. All contain one or more empirically determined "fudge factors". All gloss over numerous critical important elements of climate dynamics (such as clouds) because they are too difficult to model currently, or we lack understanding of their mechanisms.<p>The idea that anyone anywhere on Earth has some pristine from-first-principles climate model that you can input data into, turn some crank and spit out data on the climate of the future with any degree of certainty is just plain <i>wrong</i>. Nobody has an accurate model of climate. The AGW proponents have been claiming that they have created accurate climate models (to a degree), but the evidence to back that up is extremely thin. And, what's more, we've discovered recently that the evidence is even thinner than we thought it was.<p>This is why people object so much to the AGW doomsayers, because the evidence is very much lacking. At best, at <i>best</i>, there's a tiny window of a few decades where some models of climate show a similar trend in global average temperature to the actual trend. And on this tiniest thread of "evidence" so the entire catastrophic AGW theory and all of its proscriptives on human behavior and industry hangs.