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Multi-archive studies of climate events and archive-specific response times require synchronous time scales. Aligning common variations in the cosmogenic radionuclide production rate via curve fitting methods provides a tool for the continuous synchronization of natural environmental archives down to decadal precision. Based on this approach, we synchronize 10Be records from Western Gotland Basin (WGB, Baltic Sea) and Lake Kälksjön (KKJ, central Sweden) sediments to the 14C production time series from the IntCal20 calibration curve during the Mid-Holocene period ~6400 to 5200 a BP. Before the synchronization, we assess and reduce non-production variability in the 10Be records by using 10Be/9Be ratios and removing common variability with the TOC record from KKJ sediments based on regression analysis. The synchronizations to the IntCal20 14C production time scale suggest decadal to multi-decadal refinements of the WGB and KKJ chronologies. These refinements reduce the previously centennial chronological uncertainties of both archives to about ± 20 (WGB) and ±40 (KKJ) years. Combining proxy time series from the synchronized archives enables us to interpret a period of ventilation in the deep central Baltic Sea basins from ~6250 to 6000 a BP as possibly caused by inter-annual cooling reducing vertical water temperature gradients allowing deep water formation during exceptionally cold winters. [ABSTRACT FROM AUTHOR]

Time-series of varve properties and geochemistry were established from varved sediments of Lake Woserin (north-eastern Germany) covering the recent period AD 2010-1923 and the mid-Holocene time-window 6400-4950 varve years before present (vyr BP) using microfacies analyses, x-ray fluorescence (µ-XRF) scanning, microscopic varve chronology, and 14C dating. The microscopic varve chronology was compared with a macroscopic varve chronology for the same sediment interval. Calcite layer thickness during the recent period is significantly correlated to increases in local annual precipitation (r = 0.46, p = 0.03) and reduced air-pressure (r = -0.72, p < 0.0001). Meteorologically consistent with enhanced precipitation at Lake Woserin, a composite 500 hPa anomaly map for years with >1 standard deviation calcite layer thickness depicts a negative wave train air-pressure anomaly centered over southern Europe, with north-eastern Germany at its northern frontal zone. Three centennial-scale intervals of thicker calcite layers around the mid-Holocene periods 6200-5900, 5750-5400, and 5300-4950 vyr BP might reflect humid conditions favoring calcite precipitation through the transport of Ca2+ ions into Lake Woserin, synchronous to wetter conditions in Europe. Calcite layer thickness oscillations of about 88 and 208 years resemble the solar Gleissberg and Suess cycles suggesting that the recorded hydroclimate changes in north-eastern Germany are modified by solar influences on synoptic-scale atmospheric circulation. However, parts of the periods of thicker calcite layers around 5750-5400 and 5200 vyr BP also coincide with enhanced human catchment activity at Lake Woserin. Therefore, calcite precipitation during these time-windows might have further been favored by anthropogenic deforestation mobilizing Ca2+ ions and/or lake eutrophication. [ABSTRACT FROM AUTHOR]

Annually laminated sediments of Lake Woserin in north-eastern Germany are investigated using sedimentological and palynological methods. They facilitate high-resolution reconstruction of environmental and land-use change during ca. 7000-4000 cal. BP. Between 6100 and 5800 cal. BP, changes in woodland composition and structure are evident which coincide with a change in subsistence strategy, that is, the adoption of animal husbandry. For the remaining period, eight phases of enhanced human impact (5750-5390, 5270-5150, 4890-4750, 4670-4600, 4520-4450, 4390-4350, 4250-4170 and 4070-3930 cal. BP) are identified. Hereby, the first phase relates to an opening of the landscape in connection with the adoption of large-scale, extensive cereal cultivation. Phases of decreased human impact are generally characterised by woodland regeneration. Over-regional comparison of the results reveals similar and synchronous fluctuation of human impact in the young moraine area of the south-western Baltic region and hints at a large-scale driver. In order to evaluate the role of environmental change for human activity, evidence for coinciding shifts in palaeoclimate records and their potential implication for human-environment interactions are discussed and generally support the idea that environmental changes played an important role for the cultural development during the Neolithic in Northern Germany. Hereby, climate change probably favoured the adoption of new subsistence strategies during the early Neolithic (6100-5350 cal. BP). Furthermore, the fluctuating human impact during Middle and Younger Neolithic (5350-4100 cal. BP) could indicate a socio-economic system susceptible for short-termed climatic fluctuation. [ABSTRACT FROM AUTHOR]