Earth from base to top

Earth's climate has undergone many changes during the last billion years, including periods with extended ice caps at the poles ('icehouse') and periods when it was so hot that there was little or no ice ('greenhouse'). These variations are driven by changes in the configuration of continents and oceans due to plate tectonics, and by changes in the atmospheric CO2 content due to carbon exchange between Earth's interior and exterior: the long-term carbon cycle, which is again related to plate tectonics. In order to understand these variations, we will model the coupled Earth system from the base of the rocky mantle to the top of the atmosphere over the last 888 million years. Central to this modelling is the reconstruction of plate tectonics, that provides the link between Earth's interior and exterior. The project has four goals. First, we will constrain mantle dynamics over this long timescale (888 Ma) based on global mantle convection modelling coupled to the plate tectonics reconstruction. This allows in particular to track CO2 ingassing and outgassing. Second, we will better understand and quantify the evolution of the climate over geological time scales by determining and using palæo-elevation maps in global climate simulations. Third, we will constrain the palæogeographies of the Earth by integrating the feedbacks of mantle models and climate models. Finally, we will quantify the coupling between the different shells of the Earth from the base of the mantle to the top of the atmosphere. Such a coupled approach to the functioning of the whole Earth throughout such long timescales has never been attempted; this project creates a leading group on the topic in Switzerland, whose work will serve as a reference in many disciplines worldwide.