Modelled asymmetric Antarctic glaciation during the Eocene-Oligocene Transition

The evolution from greenhouse to icehouse climate during the Eocene-Oligocene Transition (EOT) (~34.4–33.7 Ma) is associated with a drastic cooling of global climate and significant ice sheet build-up. However, extent and location of the such early permanent ice masses are still largely unknown. Here, we coupled the AWI-Earth System Model with the Parallel Ice Sheet Model to draw a bigger picture of the relationship between Antarctic ice sheet presence and global climate dynamics during the EOT and the Early Oligocene Glacial Maximum (EOGM) just afterwards. Our model results reveal an asymmetric ice sheet cover, and notably, identify a CO2-threshold necessary for initiating marine-terminating ice sheet advance onto West Antarctic continental shelves—one major component in Earth's paleoclimatic puzzle. We identify the Southern Ocean dynamics as a direct result of Southern gateway configurations to be a key driver of East Antarctic ice sheet growth. Our Antarctic climate and vegetation simulations match available proxy data well for this period of fundamental change. Therefore, our new simulations significantly contribute to a much deeper understanding of Antarctic ice sheet growth during the EOT and subsequent EOGM, thereby highlighting the importance of Southern high latitude environmental change for controlling Earth’s climate dynamics.