Cyclones in the Mediterranean region: The present and the doubled CO2 climate scenarios

Abstract

This study investigates the variations of the cyclonic activity in the Mediterranean region that would be produced by doubling the CO2 atmospheric content. The analysis is based on the SLP (sea-level pressure) fields produced by two 30 yr long time slice experiments of the ECHAM-4 model at T106 resolution, carried out by DMI, simulating the present and doubled CO2 scenarios. The cyclonic activity in the Mediterranean region is similar in the 2 climate scenarios. The present climate is characterized with a slightly, but statistically significant, higher overall number of cyclones. The doubled CO2 simulation is characterized with more extreme weather events, but the difference between the 2 scenarios is hardly significant. No variation in the regions of formation of the cyclones was clearly identified. An, admittedly small, number of cyclones of both scenarios was simulated using a limited area model (LAM) with 0.25° resolution. These simulations do not suggest that an increased model resolution should add new major findings to the results of this study, but the possibility that a climate change signal is not evident because of the coarse T106 model resolution remains open for further investigations. However, this study does not show a large change in the regime of the cyclones in the Mediterranean region due to the atmospheric CO2 doubling.