Reconstruction of decadal to orbital-scale climate variability during Marine Isotope Stage 9 using precisely dated multi-proxy speleothem records from Central Europe – Part II

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Reconstruction of climate variability during previous interglacials as well as precise determination of their timing and duration provides important information about our climate system. Marine Isotope Stage (MIS) 9 (340,000-280,000 years BP) is a particularly important interglacial in this context because it shows the highest preindustrial atmospheric CO2 and CH4 concentrations of the last 800,000 years.In the framework of the original project, we precisely date five stalagmites from Dechen Cave (western Germany). Since Dechen Cave is located in a region with permafrost during glacial times, speleothem growth within the cave is very sensitive to warmer and wetter climate conditions. Precise dating of the growth phases of the speleothems thus enables precise determination of the timing and duration of MIS 9 and its sub-stages. In addition, we generate high-resolution δ13C and δ18O values as well as trace element records, which will result in a replicated, precisely dated multi-proxy record completely covering MIS 9.Unfortunately, the original project was severely delayed due to several reasons (construction work in the clean laboratory, several problems with the newly installed MC-ICPMS, and in particular the global COVID-19 pandemic). As a result, the analyses outlined in the original proposal could not be conducted as intended and were delayed by at least one year. Therefore, both the dating and the proxy analyses of the speleothems could not be finished in the scheduled time frame, and the interpretation of the dataset in terms of past climate variability has so far been impossible.