Climate variability and the Late Bronze Age collapse in the Peloponnese: Insights from Holocene transient simulations

The Late Bronze Age (LBA) collapse (1350–1050 BCE) marked a period of profound societal upheaval across the ancient Mediterranean, including the decline of Mycenaean civilization in the Peloponnese. While traditionally attributed to invasions by the "Sea Peoples," emerging paleo-climate evidence suggests that severe and prolonged droughts played a significant role in this collapse. A key methodology for exploring unknown past climate conditions is the use of Holocene transient simulations. This study evaluates the extent to which three Holocene transient climate simulations (MPI-ESM, TraCE-21ka, and EC-Earth3 8K) capture the prolonged arid conditions observed in regional proxies during the LBA collapse. The EcEarth and MPI models agree with lake and marine sediment, stalagmite and tree ring proxy data from across the wider region, revealing a prolonged drying trend for the Balkan area from 4800 until 1000 BCE. Focusing in on the Peloponnese region, EcEarth and MPI models agree well with the Mavri Trypa Cave δ18O record, indicating an unstable climate with extended drought periods from 1600 until 1100 BCE and recording abrupt dry pulses following 1250 BCE. The TraCE simulation, however, exhibits relatively stable behaviour, showing no marked shifts toward either wet or dry extremes during the entire period. We establish that due to differences in resolution and model parametrization, MPI and EC-Earth provide a more realistic simulation of the dynamic and variable climate conditions during the Holocene period in the Aegean region, particularly with respect to capturing prolonged droughts and abrupt climatic shifts, while TraCE seems to oversimplify these variations. From the EcEarth model, we establish that droughts in the Peloponnese and Balkan region, in the period prior to and during the LBA collapse, were a result of cooling Mediterranean sea surface temperatures, that reduced moisture into the regions hydrological cycle, supporting proxy evidence. This cooling was ultimately driven by a weakening AMOC.  By drawing parallels between the LBA collapse and contemporary climate challenges, the study underscores the importance of understanding how current and future climate variability could lead to similar societal disruptions, urging policymakers to incorporate historical insights into modern climate mitigation strategies.