Stochastic contributions to global temperature changes.

Records of the mean annual global surface temperatures from 1850 to 1970 show annual temperatures that are correlated with temperatures of the previous years as a one-dimensional random walk with a limiting feedback. This description accounts for the variation in those temperatures observed until the present by assuming that the base temperature is proportional to the increase in carbon dioxide concentration over the level in 1890. Climate models that better fit the observed variations are shown to be statistically improbable and thus likely to be artifacts.