The effect of the various greenhouse gases on the radiative forcing may be crudely estimated by setting Teff due to the ith species. Suppose that the concentration of a single species (say, CO2) were increased from t; to t; + ATi. (a) Show that the radiative forcing is given by AN; (b) Show that a CO2 doubling (for which N; change in opacity is At;/E; ti effective opacity is implied. exp[-E; t], where t; is the opacity %3| +FTOA At;. 4 W . m-2), the required 0.034; that is, only a 3% change in ||