Paleoclimatic reconstruction from marine records of central and western Mediterranean area over last five millennia using planktonic foraminifera

Over the last millennia, the Mediterranean Sea was affected by very significant shifts in climate (i.e., Luterbacher et al., 2012; Maselli and Trincardi, 2013; Cisneros et al., 2016; Margaritelli et al., 2016; Büntgen et al., 2016). Within this time intervals, the study of marine records documented short-term climate oscillations and a strong modification in climate system from the onset of the Roman Period (ca. 500 BCE) up to the present-day (i.e., Margaritelli et al., 2016 and reference therein). Planktonic foraminifera have been used to reconstruct the climate evolution of the last five millennia from marine sediment cores of western and central Mediterranean Sea. We provide the comparison between planktonic foraminiferal paleoclimatic curves obtained from different of Mediterranean environmental areas basin : i) western Sicily Channel (Margaritelli et al., in prep., core water depth 475 mbsf); ii) Minorca Basin (Margaritelli et al., in prep., core water depth 2117 mbsf); iii) north Tyrrhenian Sea (Lirer et al., 2014, core water depth 87.2 mbsf) and iv) central Tyrrhenian Sea (Margaritelli et al., 2016, core water depth 93 mbsf) (Fig. 1). These results are compared with paleoclimatic curves from extra Mediterranean marine areas (Indian Ocean, Munz et al., 2015; southern California, Fisler and Handy 2008) to evaluate the geographical extent of the recognised climatic variability. The planktonic foraminiferal paleoclimatic curves document an overall warm and stable climatic condition from 3500 BCE to 750 BCE, corresponding to low amplitude oscillation in D14C residual and to a period where NAO index does not show particular trend and/or main oscillation. From 750 BCE to ca. 250 BCE, the Mediterranean and extra-Mediterranean paleoclimatic curves document a transition-cooling phase, which becomes consistent at ca. 250 BCE, in correspondence of the sharp global cooling related to Homeric solar minimum. This short time interval (750 BCE - ca. 250 BCE) corresponds to the well-known Sterno-Etrussia excursion in terrestrial magnetic field. The global cooling over the last two millennia, related to the decrease in insolation, is documented by the parallelism of all planktonic foraminiferal paleoclimatic curves, showing an isochronous response of Mediterranean and extra-Mediterranean planktonic foraminifera. This long-term cooling trend results parallel to a progressive trend vs negative anomaly in D14C residual as well as parallel to the shift of NAO index trend toward positive values and reach the maximum cooling during the Little Ice Age at ca. 1800 CE (Maunder Minimum). At ca. 550 CE the planktonic foraminiferal paleoclimate curves show a further cooling phase, which age corresponds to the Late Antique Little Ice Age (LALIA), considered as an additional environmental factor contributing to the establishment important change in human culture. At 1800 CE, the paleoclimatic curves show a turnover vs the modern warm climate condition. This comparison will provide a more complete high-resolution picture about the climate changes in the Mediterranean region and the validity of planktonic foraminifera as tool for global paleoclimate reconstruction over the last five millennia. We acknowledge financial support from the Italian Project of Strategic Interest NEXTDATA (http://www.nextdataproject. it) "A national system for recovery, storage, accessibility and dissemination of environmental and climatic data from mountain and marine areas".