Excellent article in Skeptic by the chemist Patrick Frank, who demonstrates in great detail the total unreliability of the climate models on which the claim that man-made CO2 is responsible for the current warming of Earth's climate. There is a downloadable pdf, but the conclusion follows:
Some may decide to believe anyway. “We can’t prove it,” they might say, “but the correlation of CO2 with temperature is there (they’re both rising, after all), and so the causality is there, too, even if we can’t prove it yet.”
But correlation is not causation, and cause can’t be assigned by an insistent ignorance. The proper response to adamant certainty in the face of complete ignorance is rational skepticism. And aren’t we much better off accumulating resources to meet urgent needs than expending resources to service ignorant fears?
So, then, what about melting ice-sheets, rising sea levels, the extinction of polar bears, and more extreme weather events? What if unusually intense hurricane seasons really do cause widespread disaster? It is critical to keep a firm grip on reason and rationality, most especially when social invitations to frenzy are so pervasive.
General Circulation Models are so terribly unreliable that there is no objectively falsifiable reason to suppose any of the current warming trend is due to human-produced CO2, or that this CO2 will detectably warm the climate at all. Therefore, even if extreme events do develop because of a warming climate, there is no scientifically valid reason to attribute the cause to human-produced CO2.
In the chaos of Earth’s climate, there may be no discernable cause for warming. Many excellent scientists have explained all this in powerful works written to defuse the CO2 panic - but the choir sings seductively and few righteous believers seem willing to entertain disproofs