Climate of the Past www.clim-past.net 1814-9324 1814-9332 5 4 2009 10.5194/cp-5-713-2009 http://www.clim-past.net/5/713/2009/ http://www.clim-past.net/5/713/2009/cp-5-713-2009.html http://www.clim-past.net/5/713/2009/cp-5-713-2009.pdf 713 720 2009-11-19 The response of Mediterranean thermohaline circulation to climate change: a minimal model P. Th. Meijer meijer@geo.uu.nl H. A. Dijkstra Department of Earth Sciences, Faculty of Geosciences, Utrecht University, The Netherlands Institute for Marine and Atmospheric Research Utrecht, Utrecht University, The Netherlands Physics-based understanding of the effects of paleoclimate and paleogeography on the thermohaline circulation of the Mediterranean Sea requires an ocean model capable of long integrations and involving a minimum of assumptions about the atmospheric forcing. Here we examine the sensitivity of the deep circulation in the eastern Mediterranean basin to changes in atmospheric forcing, considered a key factor in the deposition of organic-rich sediments (sapropels). To this extent we explore the setup of an ocean general circulation model (MOMA) with realistic (present-day) bathymetry and highly idealized forcing. The model proves able to qualitatively capture some important features of the large-scale overturning circulation, in particular for the eastern basin. The response to (i) a reduction in the imposed meridional temperature gradient, or (ii) a reduction in net evaporation, proves to be non-linear and, under certain conditions, of transient nature. Consistent with previous model studies, but now based on a minimum of assumptions, we find that a reduction in net evaporation (such as due to an increase in freshwater input) may halt the deep overturning circulation. 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