MULTI-PROXY EVIDENCE FOR CHANGES IN LATE GLACIAL/EARLY HOLOCENE CENTRAL MEDITERRANEAN SURFACE WATERS

The semi-enclosed Mediterranean basin is located in a transition zone between a humid climate to the north and an arid climate to the south and is, therefore, particularly sensitive to changes in the climate system. The modern Mediterranean has a negative water balance and salinity in the basin is controlled by the amount of incoming water from the Atlantic, evaporation, precipitation, and runoff from around the basin.

During the late Glacial and early Holocene several abrupt climatic events (the Younger Dryas, the 8,200 cal yr event, and the 7,500 cal yr event) are recorded from ice cores and other climate proxies. These events are thought to have coincided with reorganizations in human societies in the Mediterranean region. Climate records from the region record the Younger Dryas climate reversal but it is still uncertain what effect it had in the Mediterranean and how widespread it was. A cooling at 7,500 cal yr is recorded only in one core in the Adriatic Sea.

To identify short-term climatic events in the central Mediterranean during the late Glacial to early Holocene and their nature, high-resolution samples from two cores in the western and eastern Ionian Sea were analyzed using foraminiferal species assemblages and oxygen isotopes. The Younger Dryas was found in both cores and is marked by a prolonged and significant lowering in surface water salinity, more significant in the core located offshore southern Italy and thus closer to surface water runoff from the northern shores of the Mediterranean. A decrease in seasonality is also observed during this event. The multi-proxy approach allows us to rule out a significant surface-water cooling and instead identify increased precipitation in the northern part of the Mediterranean during this time. Only one of the cores analyzed extended into the Holocene and no significant change in either water temperature or salinity was observed.