Possible Climate Change Scenarios with Specific Reference to Mediterranean Regions

The Mediterranean basin is one of the most sensitive areas of the world regarding possible consequences of the present, anthropogenic-induced climate change. Besides temperature increase, most models consistently project rainfall decreases both on annual basis and for all seasons. On the basis of results from general circulation models (as presented in the recent Fourth Assessment Report of the IPCC) and also from results of several downscaling studies applied to Europe and the Mediterranean areas, some quantitative projections are summarized in this chapter. On average for the region, temperature is projected to increase about 3.5°C on an annual basis by the end of this century, with remarkable differences among specific areas. Precipitation could be reduced more than 10% (annual and regional average), the decrease being larger in summer and in the southern areas of the region. There are many uncertainties involved in these projections; basically, they derive from the unknown future emissions of greenhouse gases and aerosols, from the knowledge gaps of the complex climatic system, and from limitations of models and downscaling techniques. Despite these uncertainties, it is highly probable that water availability will be reduced in the Mediterranean areas as a consequence of increased temperatures and decreased and more variable precipitation. This result should be taken into account by water management agencies, concerned stakeholders and society in general.