LATE BRONZE AGE COLLAPSE AT USTICA ISLAND (SICILY - ITALY): THE DROUGHT HYPOTHESIS

Ustica is a small island in the southern Tyrrhenian Sea. During the Middle Bronze Age, hundreds of inhabitants were primarily concentrated in the fortified citadel of Villaggio dei Faraglioni. The site was suddenly abandoned between 1250 and 1200 BCE, and the entire island remained uninhabited for eight centuries. Several hypotheses have been put forward to explain this abandonment, including the occurrence of a natural catastrophe or an unexpected hostile invasion. Here, we explore an alternative explanation: the impact of climate change, with a particular focus on drought. Ustica remained uninhabited during a period of global and regional climatic deterioration, coinciding with sunspot minimum and stratospheric sulfate injection, from unknown explosive volcanic eruptions. Both northern and southern offshore areas of Sicily recorded prolonged and strengthened northerly atmospheric activity, which cooled sea surface temperatures and enhanced the water column vertical mixing. Stable isotope data from speleothems in northern Spain and central Italy indicate pronounced drought episodes following Ustica's abandonment at 3.15 ka BP, coinciding with a predominantly positive North Atlantic Oscillation phase. Locally, reduced precipitation levels are evidenced by significant dryness in Sicily between 3.2 and 3.0 ka BP, as reflected in lake level fluctuations. The severe drought affecting Sicily and Ustica between 3.2 and 3.0 ka BP appears to be the culmination of a broader aridification trend that had been ongoing at both global and regional scales since the 4.2 ka BP event. Water shortages may have led to sanitary issues, crop failures, and famine. Though speculative, our hypothesis provides a more plausible explanation for the well-preserved pottery and defensive walls at Villaggio dei Faraglioni, than scenarios involving natural catastrophes, invasions, or looting.