Global marine biogeochemical cycles during the Paleocene-Eocene Thermal Maximum with a vertically one-dimensional ocean model

Abstract

The Paleocene-Eocene Thermal Maximum (PETM) was a significant warming event that occurred approximately 56 Ma (million years ago). Geological studies have shown that the carbon isotope ratio decreased by 2 to 3 per mil over approximately 10,000 years, and the difference in the carbon isotope ratio between surface water and deep water almost disappeared. These changes are thought to have been caused by the dissociation of methane. However, few studies have focused on the vertical structure of the carbon isotope ratio and examined how marine biogeochemical cycles changed during the PETM. We therefore investigated the marine biogeochemical cycles during the PETM using a vertically one-dimensional ocean model and elucidated the behavior of the marine carbon isotope ratio. The results indicate that the duration of methane influx was shorter than previously thought and the ocean circulation was stagnant just after the event.