Quantitative climate reconstruction for MIS 3 in Central Europe based on multi-proxy data from precisely dated speleothems (flowstones) from Bleßberg Cave, Germany

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The last glacial period exhibited much larger climate variability than the Holocene. In particular, Marine Isotope Stage (MIS) 3 (ca. 57-27 ka) was characterised by rapid climate oscillations (the Greenland Interstadials), which show rapid warming followed by gradual cooling. The impact of these interstadials in Central Europe is not clear yet. In terrestrial northern western Europe (>50° N), fragmentary organic deposits intercalated in non-organic glacial deposits are interpreted as evidence for interstadials, and pollen analysis indicates open, treeless vegetation. In northern central Europe, interstadials are typically characterised by tundra vegetation with a variable component of shrubs and sparse boreal trees. Due to chronological uncertainties, precise assignment of the terrestrial European interstadials north of 50° N to particular Greenland Interstadials is not possible.Speleothems have great potential for climate reconstruction, in particular because they can be dated very precisely by the 230Th/U-method. North of 47° N, speleothem growth during MIS 3 in Europe has so far only been detected in three caves. For two of those, only 230Th/U-ages, but no climate proxy data have been reported. Thus, there is only a single MIS 3 speleothem proxy time series from Central Europe available, which is restricted to two growth phases from ~52 to ~51 and ~47 to ~43 ka. This suggests that climate was too cold and/or dry during large parts of MIS 3 to enable speleothem growth north of the Alps in Central Europe.Here we propose to study two speleothems from Bleßberg Cave, eastern Germany. These flowstones show several growth periods during MIS 3 that have not been detected yet in other speleothems from Central Europe. This provides the unique opportunity to obtain precisely dated palaeoclimate information for these intervals, which reflect the impact of Greenland interstadials in terrestrial Europe. This is of particular interest because Bleßberg Cave is located at ca. 50 °N, beyond the northern limit for temperate forest development during MIS 3 in Europe.We will generate a precisely dated multi-proxy climate record for MIS 3 and the Late Glacial including d13C and d18O values, trace elements, Sr isotopes as well as dD and d18O values in speleothem fluid inclusions. Furthermore, we will apply a unique and novel combination of cave monitoring, isotope-enabled climate modelling and modelling of processes occurring in the soil and karst above the cave to obtain a better understanding of the processes influencing the proxy signals at the cave site and to disentangle the factors influencing the speleothem d18O values. This should enable us to provide a quantitative reconstruction of climate variability during MIS 3, which will then be compared with Holocene proxy records from Bleßberg Cave as well as with other global and regional climate records to reconstruct spatial variability and potential tele-connections.