Insights into the warm interval of the mid-Pliocene from geodynamic and climate modelling

The mid-Pliocene warm period, roughly 3--3.3 million years ago (Mya), was the most recent time period during which the global temperature was higher than present day for an interval of time longer than any of the Pleistocene interglacials. This thesis reports on an extensive analysis of diverse attributes of the mid-Pliocene based on numerical geodynamic and climate modelling. On the basis of geodynamic modelling we infer that the globally averaged sea level during this time period was $15\pm7$ m higher that present day. In the most likely scenario, $\sim\!7$ m originated from the ice contained in the Greenland ice sheet which is known to have been absent at this time, $\sim\!5$ m from the West Antarctic ice sheet which is very susceptible to a runaway instability and likely had disintegrated under the warm mid-Pliocene climate and the remaining coming from coastal subglacial basins in East Antarctica. Furthermore, informed by the ESL estimate, we provide a reconstruction of the orography and the bathymetry of the mid-Pliocene. The climate modelling investigation has focused on understanding the characteristics of the $\sim\!400$ ppmv climate, the mechanisms and feedback processes supporting the warming, and on the comparison of modelled results with proxy inferences. It is found that with the latest constraints on the boundary conditions for the mid-Pliocene the fidelity of simulated climate to those proxies has been significantly improved. Our analysis suggests the mid-Pliocene warming was strongly enhanced by feedback processes operating over the long interval of relatively stable climate.Ph.D