Over recent decades, the ocean has experienced substantial oxygen loss, affecting marine ecosystems and fisheries. However, the future response of ocean deoxygenation to global warming remains controversial. The history of past ocean deoxygenation events can offer mechanistic insights into its future evolution. Of particular interest is the Paleocene-Eocene Thermal Maximum (PETM), where the magnitude of carbon emission is analogous to the RCP8.5 scenario. Recent studies suggest that the impact of global warming on ocean deoxygenation during the PETM is more complex than previously understood, highlighting the need for further investigation into the extent and spatial distribution of oceanic oxygen changes. Here, we present the compilation of various redox proxy data from DSDP/ODP/IODP cores to discuss the latest findings on ocean oxygen minimum zones at subsurface water depths and bottom water oxygen at bathyal-to-abyssal depths across the global open ocean. We also combine proxy data and model simulations to explore potential mechanisms of transient ocean deoxygenation during the PETM, including temperature, productivity, and circulation. These findings demonstrate the potential spatial variability of oceanic oxygen change during the PETM, with implications for past and future warming scenarios.
 

Paleocene-Eocene Thermal Maximum,Global warming,ocean deoxygenation,oxygen minimum zones,bottom water oxygen