Aridity of the Mediterranean Sea at the Last Glacial Maximum: A reinterpretation of the δ18O record

Paleoclimate data show conflicting evidence for aridity in the Mediterranean basin at the last glacial maximum (LGM). Two recent modeling studies of the LGM Mediterranean, using water‐balance/biome and ocean general circulation models, respectively, suggest that evaporation over the basin was reduced at the LGM compared with today. In apparent conflict with these results is the strongly enhanced δ18O signature of the LGM Mediterranean surface waters, particularly in the eastern basin, which has been ascribed to a much higher salinity. In an alternative interpretation presented here, a box model of the balance between paleoclimate model evaporation and rainfall and paleoceanographic model advective terms shows that the observed LGM δ18O signature can be reproduced without the need for an enhanced salinity, with advection playing the dominant role in the δ18O budget. The box model also shows that the δ18O data alone are insufficient to determine the type of exchange between the eastern and western basins. The results emphasize that regional paleoceanographic water balances should consider all relevant processes, and not just the evaporative flux.