Modelling the sensitivity of Mediterranean Outflow to anthropogenically forced climate change

The possible future impact of anthropogenic forcing upon the circulation of the Mediterranean, and the exchange through the Strait of Gibraltar is inv estigated using a Cox-type model of the Mediterranean at 0.25 degrees x 0.2 5 degrees resolution, forced by "control" and "greenhouse" scenarios provid ed by the HadCM2 coupled climate model. The current structure of the Medite rranean forced by the "control" climate is compared with observations: cert ain aspects of the present circulation are reproduced, but others are absen t or incorrectly represented. Deficiencies are most probably due to weaknes ses in the forcing climatology generated by the climate model, so some caut ion must be exercised in interpreting the enhanced greenhouse simulation. C omparison of the control and greenhouse scenarios suggests that deep-water production in the Mediterranean may be reduced or cease in the relatively n ear future. The results also suggest that the Mediterranean outflow, may be come warmer and more saline, but less dense, and hence shallower. The volum e of the exchange at the Strait of Gibraltar seems to be relatively insensi tive to future climate change, however. Our results indicate that a paramet erisation of Gibraltar exchange and Mediterranean Outflow Water (MOW) produ ction may be able to provide adequate representation of the changes we obse rve for the purposes of the current generation of climate models.