Climate Reconstruction and Monitoring in the Mediterranean Sea: A Review on some Recently Discovered High-Resolution Marine Archives

Abstract

Palaeoclimate records are important tools for understanding climate modifications and contextualizing recent anthropogenic perturbations in climate change relative to natural variability in the Earthclimate system. Moreover, time-series proxy records of the main physical and chemical parameters in marine and continental environments are increasingly used for testing climate models in order to ascertain the reliability of projections for future scenarios in our greenhouse modified Earth. In order to account for the limited number of continuous instrumental measurements of climatic variables in the past, such as sea surface temperature (SST), salinity (SSS), sea-level fluctuations and water chemistry, a complementary approach is the examination of geochemical tracers (i.e. trace elements and stable isotopes) in well-dated natural marine archives. Recently, the Mediterranean Sea has been the focus of a number of studies where new high resolution climate archives have been investigated utilizing proxies for sea surface temperature, salinity,marine chemistry, and ocean circulation, different to those available for tropical regions. In particular, vermetids (Dendropoma petraeum), non-tropical zooxanthellate corals (Cladocora caespitosa) and cold-water corals (Desmophyllum dianthus, Lophelia pertusa and Madrepora oculata) have been studied by conventional and advanced analytical techniques (e.g., laser ablation ICP-MS, MC-ICP-MS, synchrotron X-ray fluorescence) and have been successfully used as high-resolution palaeoenvironmental proxies. Vermetid reefs have the potential to yield valuable information on past sea-level changes and SST, through the combination of stable isotopes and radiocarbon dating. The trace element concentration, in combination with U-series and radiocarbon dating, of the skeletal aragonite of the Mediterranean zooxanthellate coral Cladocora caespitosa, and of the coldwater corals Desmophyllum dianthus and Lophelia pertusa, has been successfully demonstrated to be a valid high-resolution SST archive, and a seawater chemistry and ocean circulation proxy, respectively. Here we present a review of our research over the last few years, aiming for the establishment of new natural marine archives collected from various sites of the Mediterranean Sea, reporting on our methodological approaches and main results.