Limited summer cooling but enhanced aridity in southwestern Iberia during the 8.2 ka event

Relatively warm and wet conditions prevailed in the southwestern Mediterranean during the Early–Middle Holocene transition, as indicated by multiple paleoclimate archives. However, the impact of the global 8.2 ka cooling event, which may have disrupted such climatic stability, remains poorly documented in the southern Iberian Peninsula. Here, we combine the stable isotope composition of gypsum (δ 17 O, δ 18 O and δ 2 H) and coeval biogenic carbonate (δ 18 O) in sediments from Medina Lake to reconstruct the hydroclimate evolution in southwestern Iberia from 9.5 to 7.0 cal ka BP, including the 8.2 ka event. By applying an isotope mass-balance model, we found that the lake functioned as a (semi-)permanent water body through this period, except for a short-lived interval at 8.3–8.1 cal ka BP. At that time, the lake shifted to a more ephemeral state with a reduced hydroperiod. This transition was associated with decreased precipitation and lower atmospheric relative humidity. Paleotemperature estimates obtained from tandem measurements of δ 18 O in gypsum hydration water and ostracod shells reveal that warm-season lake water temperatures at Medina Lake during the 8.1–8.3 cal ka BP interval (25.2 ± 3.1 ° C) were comparable to current instrumental summer lake water temperatures (27.2 ± 4.6 ° C) in short-hydroperiod lakes of southern Iberia. This suggests limited or no significant summer cooling in response to the 8.2 ka event compared to present-day conditions. Overall, our results indicate that the 8.2 ka event in southern Iberia was primarily characterized by enhanced warm-season aridity rather than pronounced cooling, in agreement with other paleoclimate records from the western Mediterranean.