Return periods of global climate fluctuations and the pause

An approach complementary to General Circulation Models (GCMs), using the anthropogenic CO2 radiative forcing as a linear surrogate for all anthropogenic forcings [Lovejoy, 2014], was recently developed for quantifying human impacts. Using preindustrial multiproxy series and scaling arguments, the probabilities of natural fluctuations at time lags up to 125 years were determined. The hypothesis that the industrial epoch warming was a giant natural fluctuation was rejected with 99.9% confidence. In this paper, this method is extended to the determination of event return times. Over the period 1880-2013, the largest 32 year event is expected to be 0.47 K, effectively explaining the postwar cooling (amplitude 0.42-0.47 K). Similarly, the pause since 1998 (0.28-0.37 K) has a return period of 20-50 years (not so unusual). It is nearly cancelled by the pre-pause warming event (1992-1998, return period 30-40 years); the pause is no more than natural variability.