Inconsistencies between observed, reconstructed, and simulated precipitation indices for England since the year 1650 CE

Abstract

The scarcity of long instrumental records, uncertainty in reconstructions, and insufficient skill in model simulations hamper assessing how regional precipitation changed over past centuries. Here, we use standardised precipitation data to compare global and regional climate simulations and reconstructions and long observational records of seasonal mean precipitation in England and Wales over the past 350 years. The effect of the external forcing on the precipitation records appears very weak. Internal variability dominates all records. Even the relatively strong exogenous forcing history of the late 18th and early 19th century shows only little effect in synchronizing the different records. Multi-model simulations do not agree on the changes over this period. Precipitation estimates are also not consistent among reconstructions, simulations, and instrumental observations regarding the probability distributions’ changes in the quantiles for severe and extreme dry or wet conditions and in the standard deviations. We have also investigated the possible link between precipitation and temperature variations in the various data sets. This relationship is also not consistent across the data sets. Thus, one cannot reach any clear conclusions about precipitation changes in warmer or colder background climates during the past centuries. Our results emphasize the complexity of changes in the hydroclimate during the most recent historical period and stress the necessity of a thorough understanding of the processes affecting forced and unforced precipitation variability.