Hydrological changes in the Mediterranean Sea over the last 30,000 years

Abstract

Sea surface temperatures were reconstructed over the last 30,000 years from alkenone paleothermometry (SST-alk) and planktonic foraminifera assemblages using the Modern Analog Technique (MAT) (SST-foram) along two cores of the Mediterranean Sea: MD84-632 (Levantine basin) and MD04-2797 (Siculo-Tunisian Strait). Oxygen isotope of planktonic foraminifera G. bulloides for core MD04-2797 and G. ruber for core MD84-632 were also determined. SST-alk in the Levantine basin indicate colder values at the Last Glacial Maximum (LGM) (∼14°C) than earlier established from MAT, and a cooling amplitude of 6°-7°C, comparable to the central Mediterranean Sea. Climatic events such as the Younger Dryas (YD) and Heinrich events 1 and 2 (H1 and H2) were times of significant cooling in the two cores. In the Eastern basin, values of local seawater oxygen isotope, δw, indicate relatively saltier waters during the LGM and deglaciation than today, with increasing δw values (higher salinity) in the Eastern basin and decreasing ones (lower salinity) in the central Mediterranean Sea, during cold stadials. The observed alterations of surface water properties (T and δw) in the central and eastern Mediterranean at the LGM are consistent with model experiments showing slightly lower evaporation in the Mediterranean than today, except for the Eastern basin. Copyright 2007 by the American Geophysical Union.