Final conference, Rome October 11, 2016 Fine scale correlation between palaeoclimatic polar data and isotopic composition of speleothems from Corchia Cave (Central Italy) Isola I.1, Zanchetta G.1,2, Regattieri E.3, Drysdale RN. 4, Hellstrom J. 5 1Istituto Nazionale di Geofisica e Vulcanologia ilaria.isola@ingv.it; 2Department of Earth Sciences, University of Pisa, Italy 3Institute of geology and mineralogy, University of Cologne, Germany 4School of Earth Sciences, University of Melbourne, Australia 5Department of Resource Management and Geography, University of Melbourne, Australia Abstract The Arca Project aim is to investigate the extreme meltwater in terms of events from both palaeoclimatic and modern air-sea-ice interaction. Here we focus on the recognition of the expression of high-latitude Holocene palaeoclimatic variations in the medium-latitude palaeoclimatic archives. The climate in the Polar Regions and in the North West Europe is mainly controlled by the North Atlantic Oscillation (NAO), defined as the difference in atmospheric pressure at sea level between the Icelandic low and the Azores high (Hurrell & Deser, 2009; Olsen et al., 2012). The variation of NAO, expressed as NAO index positive (NAO+) or negative (NAO-), is strongly linked to the position of the Atlantic westerly wind jet (AWJ) and consequently to the storm tracks in the North Atlantic, which exert a strong effect on the amount of precipitation in western Europe and on the δ18O of rainfall (Olsen et al., 2012; Smith al., 2016). During NAO+, the South Polar Gyre (SPG) current is stronger, it is more E-W oriented making the Atlantic inflow fresher (Thornalley et al., 2009), AWJ are stronger and their tracks migrate northwards leading to wetter and warmer conditions in the North of Europe and dryer in the South including the western Mediterranean (Cacho et al., 2001). Reversely on NAO- conditions the SPG current is weaker and N-S oriented making the Atlantic inflow saltier, AWJ are weaker and their tracks shift southward leading to wetter and warmer condition in the South of Europe and dryer in the North. (Fig. 1). Within the framework of the ARCA project we studied geochemical proxies (δ18O and δ13C isotopes and trace element variations) from cave carbonate deposits (speleothems) from the Corchia Cave in the Apuan Alps mountain chain (Central Italy, Fig. 1), in order to highlight the main climatic events occurred during the Holocene and their relationship with climatic variations at high latitudes. δ18O values from continental carbonate in the Mediterranean are usually interpreted as indicating drier conditions during periods of increased values and wetter conditions for decreasing trends associated with a marked “amount effect” on rainfall (Bard et al., 2002; Drysdale et al., 2009). Similarly increasing δ13C values are interpreted as lower biogenic CO2 supply, which can result from either short soil–water residence times or minimal soil and vegetation cover above the cave (McDermott, 2004; Drysdale et al., 2004). The Apuan Alps are a mountain range abruptly rising from the narrow coastal plain of the Tyrrhenian seaboard to about 2000 m a.s.l. They represent a natural barrier to humid westerly air masses of North Atlantic provenance (Fig. 1), which bring annual precipitation reaching 3000 mm/yr. Figure 1: Simplified North Atlantic climate system. SPG Sub Polar Gyre, STG Sub Tropical Gyre, orange to yellow and blue to light green curves are the major thermohaline ocean currents. Black arrows show Atlantic Wind Jet tracks: the thicker arrow shows the tracks of the stronger AWJ under NAO+ conditions, the thinner one shows the tracks of weaker AWJ under NAO- conditions. (modified by Smith et al., 2016). The red dot indicates the Corchia Cave position.