If only there were some sort of life form that required carbon dioxide to live, and which was prolific enough that any increase in atmospheric CO2 would almost immediately result in a surge in that life form's population and fecundity to take advantage of the sudden increase in the one resource it most needed to survive. Even better, that life form would thrive most when temperatures climbed, so that any possible greenhouse effect resulting from the increase in CO2 would only serve to make the world even more hospitable to that lifeform.
Oh wait...
