Thursday 27 January, 4 PM CET
DR. ALEXANDRA AUDERSET
ABSTRACT: Dissolved oxygen (O2) is essential for most modern ocean ecosystems, fueling organisms’ respiration and facilitating the cycling of carbon and nutrients. Oxygen measurements have been interpreted to indicate that the ocean’s oxygen-deficient zones (ODZs) are expanding under global warming. However, models provide an unclear picture of future ODZ change, on both short and long time scales. In this talk, I will present foraminifer-bound nitrogen isotopes and TEX86 paleotemperature estimates, which help to describe changes in the ODZ-hosted process of denitrification across two Cenozoic warm periods: the Middle Miocene and Early Eocene Climate Optima (the MMCO and EECO). The data show that both climate optima were associated with much lower rates of water column denitrification. These observations suggest that, in periods of sustained warmer climate, ODZs are contracted, not expanded.