Last Glacial central Mediterranean hydrology inferred from Lake Trasimeno's (Italy) calcium carbonate geochemistry

There is still apaucity of hydrological data explaining the relationship between (rapid, millennial-scale) climate forcingand Mediterranean rainfall since the Last Glacial. We show that distinct lake-level fluctuations at Lake Trasimeno(Italy) are associated with changing aridity in the central Mediterranean during the last ~47 800 years. The lake-levelfluctuations are reconstructed based on carbonate mineral content and carbonate mineral species, as well as the stableoxygen and carbon isotope (delta18O and delta13C) geochemistry of endogenic carbonates. Low lake levels are linked to highcarbonate, Mg-calcite and aragonite contents, and high delta18O and delta13C values. Inferred hydrological changes are linkedto glacial-interglacial and, tentatively within the limitations of our chronology, to millennial-scale climate variabilityas well as the intensity of the Atlantic Meridional Overturning Circulation (AMOC). Prior to the Last GlacialMaximum (LGM), during intervals equivalent to Marine Isotope Stage 3 (MIS 3), a stronger AMOC associated withGreenland interstadial periods (Dansgaard/Oeschger (D/O) warm periods) and stronger Asian monsoon probablycoincide with increased precipitation in central Italy as inferred from high lake levels at Lake Trasimeno. Periods ofweak AMOC intensity such as during Greenland stadials (D/O cold periods), during Heinrich events, and weak Asianmonsoons are correlated with lake level low stands, which imply relatively dry conditions in central Italy. LakeTrasimeno's water level during the LGM and the Late glacial (MIS 2) is relatively stable, with recorded changesshowing distinct similarities to orbital configurations. Although muted, high latitude climate forcing is still evident inthe data during peak glacial conditions. The transition from D/O-like hydrological variability at Lake Trasimenoduring MIS 3 to orbitally controlled fluctuations during the Late glacial to Holocene transition coincides with anincreasing amplitude in local winter and summer insolation, probably indicating increasing seasonality and a largertemperature gradient between low- and high-latitude settings.