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The Mediterranean region within a global climate change perspective.
Lionello P., Scarascia L.
Numerical simulations remarkably agree that future increase of greenhouse gas concentrations will cause a progressive future increase of temperature and decrease of precipitation in the Mediterranean region and amplify the trends that have already been observed in the last decades of the 20th century. Temperature and precipitation changes increase over time and depend on the evolution of anthropogenic emissions (high emission levels will produce large temperature increase and decreases in precipitation). This contribution revises the evidence of ongoing changes, summarizes the results of numerical simulations, and includes a novel analysis linking regional changes to the global surface temperature increase. Simulations indicate that the Mediterranean temperature will increase more than the global average surface temperature (consistently with the overall tendency to a future decrease of the equator-to-pole temperature gradient), but similarly to that of other areas located in the same latitude band. In particular, in summer, the Mediterranean warming rate will be 50% larger than the global one. In contrast to the intensification of the global hydrologic cycle, precipitation in the Mediterranean region experience a 5% decrease for each degree of global temperature rise. This reduction, abnormal in the context of global average behavior, makes the Mediterranean one of the most critical regions in the climate change context and will be more accentuated in its southern than northern areas. Comparison with ongoing observed trends show a satisfactory agreement with models for temperature, but a more problematic behavior for precipitation, whose future evolution is therefore subjected to non-negligible uncertainties.