Global surface temperature trends and the effect of World War II: a parametric analysis (long version)

Abstract

We fit 12 independent surface temperature time series (zones of latitude), 6 land- and 6 ocean-based, with a Gaussian (centered around WW2) on a quadratic background. The four polar zones are unusable. Each of the remaining 8 shows evidence of a 0.2-0.3 degree C bump, although one zone is dropped from the final analysis because of an aberrant fit. Thus, we find that a surface temperature increase around WW2 is a robust, statistically significant (5.2 sigma) feature of the data, and must either be a coincidence, due to systematic error that came and went around WW2, or direct evidence of the effect of human activity (an increase in combustion of various sorts) on the global climate. The fact that, at least in that era, the temperature recovered quickly, is encouraging. On the other hand, extrapolation of the background temperature rise predicts an increase of 0.5 degree C in the next 20 years if conditions remain the same.