Insight into summer drought in southern Italy: palaeohydrological evolution of Lake Pergusa (Sicily) in the last 6700 years

The Sicily region (central Mediterranean) is at high risk of drying and desertification caused by current warming and land management. The aim of this study is to place current climatic changes within the past trajectories and natural climatic variability of the Holocene. For this we re-examine a sediment core retrieved at Lake Pergusa covering the last ca. 6700 years. A multiproxy investigation, and in particular the oxygen isotope composition of lacustrine carbonate (delta18Oc), allowed us to reconstruct decadal- to centennial-scale hydrological changes. The wettest period occurred between ca. 6700 and 6000 cal a BP. The delta18Oc record indicates a new period of wetter conditions between ca. 3700 and 2400 cal a BP. In particular, a delta18Oc minimum between 2850 and 2450 cal a BP overlaps with the period of the 'Great Solar Minimum' and corresponds to a dramatic reduction of arboreal pollen (AP%) and to an increase in synanthropic pollen, marking the onset of Greek colonization in the region. The longest driest interval corresponds to the Medieval Climate Anomaly, whereas the highest delta18Oc values are recorded in the last 150 years. The trend of the last 3000 years suggests that, considering future climate projections, the area will experience unprecedented drying exacerbated by human impact.