Publications

The possible development of tropical cyclones over the Mediterranean Sea due to anthropogenic climate change is analysed here. A previous paper (Gaertner et al., 2007) has shown for the first time that there is a risk of such a development, based on regional climate model simulations for a high emissions scenario. The combined use of an ensemble of regional climate models nested in the same global climate model and of the cyclone phase space method from Hart (2003) as an objective way to detect tropical characteristics in the cyclones has allowed us to detect this possibility. The results show a large spread among the models, ranging from no cyclone intensity change in the future climate scenario to the development of strong tropical cyclones. A spatial and temporal comparison of the sea surface temperature with the ocurrence of intense cyclones show that though this variable is important, it’s not the only important factor. An adequate synoptic setting is needed, with high-latitude blocking conditions and an upper-level cut-off low over the Mediterranean Sea. Several important uncertainties remain to be analysed, but the existence of a theoretical mechanism for tropical cyclone formation over the Mediterranean Sea and the fact that already some observed Mediterranean cyclones show partially tropical characteristics give plausibility to the analysed risk.