Demographic dynamics between 5500 and 3500 calBP (3550-1550 BCE) in selected study regions of Central Europe and the role of regional climate influences.

With their rich Late Neolithic to Early Bronze Age archives, the Circumharz region, the Czech Republic/Lower Austria region, and the Northern Alpine Foreland are well-suited for research on potential links between human activities and climate fluctuations of this period with pronounced archaeological changes. In this paper, we reconstruct the rate and density of the available 14C data from 5500 to 3500 calBP (3550-1550 BCE). We ask to what extent population patterns varied over time and space, and whether fluctuations in human populations and their activities varied with local/regional climate changes. To answer these questions, we have compiled an extensive list of published radiocarbon dates and created 14C sum calibrations for each region. We also compare population dynamics with local and regional palaeoclimate records derived from high-resolution speleothems. At the regional scale, the results suggest a causal relationship between regional climate and population trends. Climate and associated environmental changes were thus at least partly responsible for demographic trends. These results also allow us to question the motivation for the construction of so-called "Early Bronze Age princely tombs" in the Circumharz region during a period of population decline. Among other things, it can be argued that the upper echelons of society may have benefited from trade relations. However, this process was accompanied by ecological stress, a cooling of the winter climate, a decline in the total population and an increase in social inequality.

Fossil leaf wax hydrogen isotopes reveal variability of Atlantic and Mediterranean climate forcing on the southeast Iberian Peninsula between 6000 to 3000 cal. BP.

Many recently published papers have investigated the spatial and temporal manifestation of the 4.2 ka BP climate event at regional and global scales. However, questions with regard to the potential drivers of the associated climate change remain open. Here, we investigate the interaction between Atlantic and Mediterranean climate forcing on the south-eastern Iberian Peninsula during the mid- to late Holocene using compound-specific hydrogen isotopes from fossil leaf waxes preserved in marine sediments. Variability of hydrogen isotope values in the study area is primarily related to changes in the precipitation source and indicates three phases of increased Mediterranean sourced precipitation from 5450 to 5350 cal. BP, from 5150 to 4300 cal. BP including a short-term interruption around 4800 cal. BP, and from 3400 to 3000 cal. BP interrupted around 3200 cal. BP. These phases are in good agreement with times of prevailing positive modes of the North Atlantic Oscillation (NAO) and reduced storm activity in the Western Mediterranean suggesting that the NAO was the dominant modulator of relative variability in precipitation sources. However, as previously suggested other modes such as the Western Mediterranean Oscillation (WeMO) may have altered this overall relationship. In this regard, a decrease in Mediterranean moisture source coincident with a rapid reduction in warm season precipitation during the 4.2 ka BP event at the south-eastern Iberian Peninsula might have been related to negative WeMO conditions.