Environmental and climatic variability during the Middle Würmian in the northern Alps

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The last glacial period, which is called Würmian glaciation in the Alpine region, was characterized in the northern hemisphere by strong climate variations such as Heinrich events and Dansgaard-Oeschger (D-O) cycles. The latter are well documented by isotopic variations in Greenland ice cores and named Greenland interstadials and stadials there. Outside of the Greenland ice sheet, the magnitude of the D-O cycles and their impact on the environment, however, are inadequately studied. This is especially true for the Alpine area, where they are mainly reported from discontinuous speleothem isotope records. Very little is known about the impact of short-term climate variability on the Alpine environment right before the start of the last glacial maximum in the Alps. The scarce preservation of sediment sequences from this period is the main cause for it. Here the project ALPWÜRM kicks in, in which the changes of climate, vegetation, fauna and environmental conditions during the middle Würmian shall be examined. Preliminary investigations on a 27 m long sediment profile at the inner-Alpine locality Nesseltalgraben in southeast Germany delivered an unexpected abundance of fossil remains. These provide detailed insights into the environmental conditions of the period from at least about 27,000 to 43,000 years before present (uncalibrated 14C dates), which is so far unprecedented for the Northern Alps. Already existing sedimentological, geochemical and pollen analyses shall be refined in the project in order to reconstruct sedimentary deposition conditions and vegetational changes in high resolution. Ostracod and moss assemblages, which are exceptionally preserved in the sediment, will be thoroughly investigated. Oxygen isotope analyses on ostracod valves and moss remains will be combined and will provide additional information on the temperature variations during the Mid-Würmian in the Alpine realm. A multiple dating approach will be applied, including radiocarbon dating, luminescence dating and magnetostratigraphy to provide an age model as exactly as possible. The climate and environmental records collected in the course of the project will ultimately be compared and linked with reconstructions from other archives inside and outside the Alpine realm, in order to reach a consistent climate and environmental reconstruction for the middle Würmian. The project will significantly contribute to the question of how strong the extreme climatic fluctuations in the Alps were before the last glacial maximum and which impact they had on the regional biodiversity.