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Abstract

The ocean is an important CO2 reservoir that significantly shaped the climate over glacial-interglacial time scales. Radiocarbon (14C) ventilation ages are a powerful tool to investigate the ocean circulation and carbon cycle. In this thesis, absolutely dated cold-water corals from the Eastern Atlantic thermocline were analyzed using 14C dating to assess 14C ventilation ages through time. An examination of quality control parameters at the Heidelberg 14C Laboratory confirmed optimal conditions for accurate 14C measurements. Prior to the establishment of modern circulation, the thermoclines of the North and South Atlantic acted as separate carbon reservoirs. During the last glacial, cold-water corals from the South Atlantic indicated storage of respired carbon, which likely contributed to the deglacial atmospheric CO2 release. In contrast, North Atlantic cold-water corals documented a well-equilibrated thermocline. Subsequently, the phenomenon of ”14C ventilation anomalies” was investigated, which do not fit into the prevailing framework of ocean ventilation through time. The underlying causes were discussed. Furthermore, additional criteria for data filtering have been developed. Finally, rapid changes in the marine 14C content and a relation to abrupt 14C production rate changes, an underestimated atmospheric calibration curve, as well as with climatic fluctuations were discussed.