Stalagmites record information on their environment and on climate change over long time periods and their age can be precisely and accurately measured. They have therefore been moved into the focus of paleoclimatology over the past decades. In particular, speleothem records have become immensely important in the field of radiocarbon (14C) calibration. Newly established measurement techniques and proxies enable increased data resolution and the determination of previously unknown climate-related processes.

My work focuses on utilizing 14C in stalagmites as a proxy for climate change and soil processes. This is achieved using the ratio between the atmospheric 14C signature and old (“dead”) carbon from the karstic limestone, the so-called dead carbon fraction (DCF). This talk will cover new applications of 14C in stalagmites as an indicator of climate variability in a stalagmite from an arid environment above Moomi Cave, Socotra Island. For the first time, extremely high DCF (>60%) are observed which show a clear trend towards higher 14C input caused by more abundant vegetation towards the glacial termination. Using a hydrological proxy (Mg/Ca), the correction of stalagmite 14C for climate-induced variability might allow us to disentangle separate processes in the 14C signature. In a second study, this is considered in a high-resolution 14C record from Sofular Cave, Turkey, with multiple dominant processes on the stalagmite 14C signal over its growth period between 42 and 10 kyr BP. Here, the observed data are put in context to recent studies on 14C calibration based on stalagmites from Hulu Cave, China. In the last part of the talk, a prospect is given to future efforts of 14C calibration, which will substantially benefit from this research.