Richard Lindzen is an atmospheric physicist, Emeritus Professor at MIT. From 1983 until his retirement in 2013 he was Alfred P. Sloan Professor of Meteorology at MIT: : "Doubling CO2 involves a 2% perturbation to this budget. So do minor changes in clouds and other features, and such changes are common. In this complex multifactor system, what is the likelihood of the climate (which, itself, consists in many variables and not just globally averaged temperature anomaly) is controlled by this 2% perturbation in a single variable? Believing this is pretty close to believing in magic."