Middle Bronze Age humidity and temperature variations, and societal changes in East-Central Europe

Archaeological evidence points to substantial changes in Bronze Age societies in the European-Mediterranean region. Isotope geochemical proxies have been compiled to provide independent ancillary data to improve the paleoenvironmental history for the period of interest and support the interpretation of the archaeological observations. In addition to published compositions, in this study we gathered new H isotope data from fluid inclusion hosted water from a stalagmite of the Trió Cave, Southern Hungary, and compared the H isotope data with existing stable isotope and trace element compositions reported for the stalagmite. Additionally, animal bones and freshwater bivalve shells (Unio sp.) were collected from Bronze Age archaeological excavations around Lake Balaton and their stable C and O isotope compositions were measured in order to investigate climate changes and lake evolution processes during this period. The data indicate warm and humid conditions with elevated summer precipitation around 3.7 cal ka BP (Before Present, where present is 1950 CE), followed by a short-term deterioration in environmental conditions at about 3.5 cal ka BP. The environment became humid and cold with winter precipitation dominance around 3.5 to 3.4 cal ka BP, then gradually changed to drier conditions at ∼3.2 cal ka BP. Significant cultural changes have been inferred for this period on the basis of observations during archaeological excavations. The most straightforward consequences of environmental variations have been found in changes of settlement structure. The paleoclimatological picture is well in line with other East-Central European climate records, indicating that the climate fluctuations took place on a regional scale