Predicting the past…

Assessment of the reliability of climate predictions based on comparisons with historical time series

[...] In this study, we have retrieved temperature and precipitation records, at least 100-year long, from a number of stations worldwide. We have also retrieved a number of climatic model outputs, extracted the time series for the grid points closest to each examined station, and produced a time series for the station location based on best linear estimation. Finally, to assess the reliability of model predictions, we have compared the historical with the model time series using several statistical indicators including long-term variability, from monthly to overyear (climatic) time scales. Based on these analyses, we discuss the usefulness of climatic model future projections (with emphasis on precipitation) from a hydrological perspective, in relationship to a long-term uncertainty framework.

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Among the conclusions;

…none of the models proves to be systematically better than the others… model predictions are much poorer than an elementary prediction based on the time average… future climate projections [are] not credible.

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