The Eocene–Oligocene transition (EOT, ~34 Ma) marks the pivot point between the hot greenhouse climate state of the early Cenozoic and the early icehouse world and is associated with the inception of large-scale Antarctic glaciation. This climate transition, together with the opening of the Southern Ocean gateways and changes in the connectivity between the Arctic and North Atlantic, had a large impact on ocean circulation and heat transport. Several factors, including paleogeography, temperature, cryosphere extent, and ocean circulation, changed around this climate transition but the sequence of these changes and their role as a forcing or response mechanism remains debated. Questions remain regarding the changes in the ocean’s heat storage capacity, CO₂ uptake efficiency and whether this important transition steepened the meridional temperature gradient.
Understanding the key drivers of the EOT, including oceanic changes, atmospheric CO2 variations, and feedback mechanisms, is essential not only to reconstruct the climate transition from hot greenhouse to icehouse conditions, but also to provide a reverse analogue for current and future climate changes.
This session aims to bring together researchers from different disciplines, including paleontologists focusing on Eocene-Oligocene restructuring of both terrestrial ecosystems and marine communities, geochemists applying a range of traditional or novel isotopic systems and/or organic proxies to reconstruct parameters including temperature and seawater pH, as well as climate and ice sheet modelers. Through this interdisciplinary dialogue, this session aims to improve our current understanding of the Eocene-Oligocene transition, and the feedbacks driving greenhouse to icehouse climate transitions. We invite studies covering diverse geographic regions and environments, from terrestrial environments, shallow continental shelves, to deep-sea basins. We also encourage contributions that address methodological challenges in their specific fields, including proxy calibration, multiproxy integration, modeling challenges, and uncertainty quantification, to improve the accuracy of paleoclimate and paleoecological reconstructions. Together, we aim to build a comprehensive, cross-environmental perspective on past climate transitions—to stimulate the dialogue and future collaborations across various research fields in Earth Sciences studying greenhouse to icehouse transitions.