Scenari climatici nel bacino mediterraneo

Abstract

Abstract: The available observational data indicate the existence of persistent trends in earth climate characteristics during the last century. Today the planet surface is about 0.6 °C warmer with respect to the beginning of the 20th century, and the continental precipitation are 5% - 10% higher. These changes emerged more seriously at the end of the 20th century with a record warmth during the period 1995 2000, when the surface temperature increased of about 0.15°C. Recently, strong evidences have been found that a major part of the global climate changes in the last 50 years are driven by the human-induced emissions of greenhouse gases into the atmosphere, which started after the Industrial Era. One of the major difficulties in the evaluation of possible future climate changes is related to the lack of information about future rate of emissions of greenhouse gases into the atmosphere. Its increase will depend on the political and social-economical developments. In our study we use the IPCC Third Assessment Report (IPCC 2001) scenarios, which suggest different story lines of the emissions of greenhouse gases in the atmosphere depending on the possible global developments. We also use an atmospheric general circulation model (ECHAM-4) coupled with a mixed-layer ocean to simulate the changes of the atmosphere climate characteristics driven by CO2 concentration rise, which is fixed according to the IPCC scenarios. The model results suggest that the increasing rate of emissions of CO2 in the atmosphere between the 1980s and the 2060s will cause an increase of the mean surface temperature of about 1.9 °C. The surface warming will be the strongest in the polar and sub-polar areas and during the winter season. The model indicates also an increase of the surface precipitation during this period of about 2.6 cm/yr. The global warming in the European and the Mediterranean areas is stronger over the regions of Central and Eastern Europe and Asia Minor during the winter, and over the regions of Southern Europe and Northern Africa during the summer. The largest increase of the annual mean surface temperature in the European and Mediterranean areas is about 2.5-3 °C. During winters the surface precipitation decreases over the Southern Europe and the Mediterranean area, whereas it shows a slight tendency to increase during summers.