Deltaic and coastal sediments as recorders of Mediterranean regional climate and human impact over the past three millennia

Deltaic and shallow marine sediments represent unique natural archives to study the evolutionof surface coastal ocean water properties as compared to environmental changes in adjacent continents. Seasurface temperatures (SSTs) and higher plant biomarker records were generated from the Rhone and VarRiver deltaic sediments (NW Mediterranean Sea), and three sites in the South Adriatic Sea (Central/EasternMediterranean Sea), spanning all or part of the past three millennia. Because of the high sedimentaccumulation rates at all core sites, we were able to produce time series at decadal time scale. SSTs in the Gulfof Lion and the convection area of the South Adriatic Sea indicate similar cold mean values (around 17 °C) andpronounced cold spells, reflecting strong wind-driven surface water heat loss. However, they differ in therate of postindustrial warming, which is steeper in the Gulf of Lion. The three Adriatic Sea SST records arenotably different reflecting different hydrological influence from nearshore to open sea sites. Thecompositional features of higher plant n-alkanes in the Rhone and Var delta sediments and inferredvegetation types show differences consistent with the latitudinal extension of the drainage basins of bothriver streams. In the Adriatic Sea, both coastal and open sea sediments indicate enhanced land-derivedmaterial over the past 500 years, which is not seen in the NW Mediterranean record. We suggest thatincreased erosion as the result of changes in land use practices is the most likely cause for this trend