The Middle-to-late Eocene Greenhouse Climate, Simulated using CESM (speaker: Michiel Baatsen, IMAU, Utrecht University)

Speaker: Michiel Baatsen, IMAU, Utrecht University

One of the biggest challenges currently faced by humanity is anthropogenic climate change. As a result of greenhouse gas emissions and changes in land use, the earth’s climate is warming at an accelerating pace. Both the observed and predicted mass losses at most of the polar ice sheets are of major concern due to feedbacks related to ice melt and sea level rise. In contrast to the present so-called icehouse state, earth’s climate has seen much warmer intervals referred to as greenhouse states. Under such warm conditions, without the presence of any significant ice and altered feedback mechanisms that dictate the response to an external forcing, the climate system behaves quite differently. If current warming trends continue for much longer, polar ice sheets could disappear and the climate may end up in a greenhouse state. As comparable transitions have occurred in the geological past, it is crucial to understand how they take place and to what extent the resulting climate behaves differently to that of today.

 

This research focusses on the climate of the middle-to-late Eocene (∼42-34 million years ago), leading up to one of the major climatic transitions in the known record: the Eocene-Oligocene transition (EOT). Throughout the Eocene, polar regions were mainly ice free and most of the land surface was covered with either tropical or sub-tropical vegetation. The EOT is believed to coincide with the formation of a continental ice sheet on Antarctica marking the transition from a greenhouse into an icehouse state. In order to better understand this particular transition, it is crucial to have an accurate reconstruction of the climate leading to the event. This is achieved with new geographical boundary conditions and higher resolution climate model simulations presented here. The results of those simulations allow a better understanding the late Eocene climate and the changes leading up to the EOT.