Statistical comparison of observed temperature and rainfall extremes with climate model outputs in the Mediterranean region

During the recent decades, climate model outputs have been widely used to support decision making for social and financial policies, with special focus on extreme events. Moreover, a general perception has been developed that extreme events will be more frequent in the future. To evaluate whether climate models provide a credible basis for predictions of extremes, their ability to reproduce annual extreme values of daily temperature and precipitation is studied, as well as a set of climate indices which are used to investigate the occurrence of droughts, heat waves and floods. Comparisons of climate model outputs with observed data are made in terms of probability distributions of extreme events. The case study focuses on the Mediterranean area, which is regarded to be one of the most vulnerable areas to climate change. The statistical comparison indicates that the observed extremes are not simulated sufficiently by climate models. Therefore, serious concerns are raised about the usefulness of climate models in hydrological applications.

[This research study has been submitted in several journals and was rejected; review comments and authors' replies to them are included as an Appendix]