A Modeling Study of the Messinian Salinity Crisis (MSC) Using the Slab Ocean Model Configured CAM3.1

During the Messinian Salinity Crisis (MSC), closure of the straits connecting the Mediterranean Sea with the Atlantic Ocean led to the evaporation of much of the Mediterranean, producing a subaereal depression with a depth of up to 2000 m. Although extensive geological work has been done to reconstruct the sequence of events leading up to and following the Messinian desiccation, and there has been much speculation about the impact of this event on regional and global climate, up to now, sophisticated climate modeling tools have not been brought to bear on the problem. We present preliminary results from experiments using the NCAR Community Atmosphere Model (CAM3.1) configured with a Slab Ocean Model, in which the model is run to equilibrium with varying sea levels in the Mediterranean basin. We analyze the results to detect both the regional and global climate responses that occurred. Topographically induced precipitation changes, changes in water vapor transport, the role of an exposed basin on aerosols and the resulting dust feedback on climate, as well as climate change resulting from reduced Mediterranean sea level will all be presented. In addition, we examine changes in storm paths in response to changes in large-scale synoptic circulation using the feature- tracking methodology developed by Hoskins and Hodges (2002).