The Relationship Between Radiative Forcing and Temperature: What Do Statistical Analyses of the Instrumental Temperature Record Measure?

Comparing statistical estimates for the long-run temperature effect of doubled CO₂ with those generated by climate models begs the question, is the long-run temperature effect of doubled CO₂ that is estimated from the instrumental temperature record using statistical techniques consistent with the transient climate response, the equilibrium climate sensitivity, or the effective climate sensitivity. Here, we attempt to answer the question, what do statistical analyses of the observational record measure, by using these same statistical techniques to estimate the temperature effect of a doubling in the atmospheric concentration of carbon dioxide from seventeen simulations run for the Coupled Model Intercomparison Project 2 (CMIP2). The results indicate that the temperature effect estimated by the statistical methodology is consistent with the transient climate response and that this consistency is relatively unaffected by sample size or the increase in radiative forcing in the sample.