Reconstructing absolute water-level variability of Lake Prespa (SW Balkans) during the Medieval Climate Anomaly and ‘Little Ice Age’ from a prograding beach ridge complex

Lake Prespa beach ridges register climate-driven water-level fluctuations that contain a strong North Atlantic signal. This study examines the beach ridge complex that underlies the Koula isthmus (Lake Prespa, Greece) and contains a sedimentary archive of lake-level variations spanning >5 kyr. Past lake levels were reconstructed through the accurate height survey of selected beach sediment facies that form reliable stage indicators. Here, we present the first quantitative lake level recorded in the Balkans, covering ~1 kyr, based on sediment-stratigraphic analyses and supported by five radiocarbon and six optically stimulated luminescence (OSL) age estimates. All major low/high lake phases over the past millennium were identified and dated in the sediment record. Low lake levels (842–847 m) from AD 900–1000 to AD 1430 dominated the Medieval Climate Anomaly (MCA). Generally, high water levels (>847 m) are recorded after AD ~1430, corresponding to the regional start of the ‘Little Ice Age’ (LIA), up to AD 1987. This high lake phase was interspersed by a multi-decadal water-level fall to ~846.5 m ending AD ~1650. Low levels after AD 1987 (842–845 m) were mainly caused by water abstraction. Absolute water-level changes in Lake Prespa over the past millennium mirror the pattern of hydro-climatic changes in the west-central Mediterranean, indicating that the study region belonged to this hydro-climatic domain. The observed influence of the North Atlantic Oscillation (NAO) on winter precipitation and lake level (1951–2004) is also relevant over the past ~1 kyr, as the NAO index was overall positive during the MCA and negative during the ‘LIA’.