The economy of the Mediterranean region is dominated by tourism and a prolific and varied agriculture. The agriculture requires rain, either for immediate use or stored for the dry season. The tourist, on the other hand, prefers no rain during his holiday. Meeting the expectations of the farmer and the tourist, therefore, requires a finely-balanced regional hydrology that is wet or dry at the right time of year. The effects of global warming on the precipitation regime have, until recently, been poorly understood because of the low spatial resolution of Global Climate Models. This study analyses precipitation data from four high-resolution Regional Climate Models (RCMs) to determine likely changes in drought parameters by the end of the century.

Indices of precipitation extremes are derived from daily RCM data for the periods 1961-1990 and 2070-2099, for the IPCC A and B scenarios. The analysis is performed on annual indices directly related to drought such as: the start and end days of drought, the maximum length of dry period, and the number of days per year with rainfall above some threshold. Statistically significant changes in the frequency distributions of each index are identified using non-parametric tests and mapped on a 0.5° x 0.5° grid. Where the indices are annual maxima, changes in the 50 and 100-year return period thresholds are estimated using Generalised Extreme Value models. A highly detailed picture of the likely effects of global warming on drought conditions in the Mediterranean emerges. The implications for tourism and agriculture are discussed, together with a realistic assessment of the value of mitigation strategies as defined by the A and B scenarios.