Southern High Latitude Vegetation Response to Rapid Climate Change at the Cenozoic Greenhouse to Icehouse Transition

PROJECT SUMMARY As a result of continuous burning of fossil fuel, the global environment is facing a crisis stemming from rapidly rising concentrations of carbon dioxide and other greenhouse gases in our atmosphere. Assuming greenhouse gas emissions at or above current rates, carbon dioxide will reach nearly triple the pre-industrial concentrations by the end of this century. This is expected to raise global mean temperatures to a level not seen for more than 32 million years. According to the latest assessment of the Intergovernmental Panel on Climate Change, the high latitudes will experience the largest temperature increases, resulting in a rapid melting of polar ice-sheets and global sea level rise. For a further understanding of potential changes that our world may undergo in the future, it is vital to study environmental changes during past warm periods and across major climatic thresholds. The proposed research project will reconstruct past vegetation of Antarctica and southern Australasia during the Eocene (ca 55-34 million years ago). The Eocene is a geological time period of exceptional warmth, with atmospheric CO2 concentrations exceeding triple the pre-industrial levels. The project will reconstruct past vegetation by analysing pollen in sediments deposited during Eocene times. Vegetation provides detailed information on a number of important environmental parameters, such as annual temperature and precipitation, length of growing season, minimum and maximum temperatures, and soils. Of particular interest for this study are very short-lived time intervals during the early and late Eocene, during which carbon dioxide concentration and temperatures changed rapidly. For a full understanding of their climate forcings and mechanisms, the analysed sediments must have a high time resolution and unambiguous dating control, in order to relate them to respective past climate events. The marine cores 1171 and 1171, taken offshore Tasmania as part of the International Ocean Deep Drilling Programme Leg 189, as well as Eocene rock outcrops at Cape Foulwind in New Zealand, have been chosen for the proposed study, as they provide an unprecedented opportunity to produce high resolution pollen records for Antarctica and adjacent sub-polar regions. The data will be interpreted in a global context and related to Arctic palaeoenvironmental reconstructions by integrating them into the global GIS database TEVIS (Tertiary Environment and Vegetation Information System). The TEVIS dataset will be compared with a number of simulations using the cutting edge Hadley Centre climate model (used within the climate assessment reports of the Intergovernmental Panel of Climate Change IPCC). By combining regional high-resolution pollen analyses with global data-model comparison, this proposed study will foster a deeper understanding of how the terrestrial environments and polar ice sheets responded, and might respond in the future, to rapid changes in temperatures and atmospheric CO2 concentration. By indicating weakness and strength, the data-model comparison will also contribute to the improvement of climate models that we rely upon for simulating future climate change.