Under many projected emissions scenarios, atmospheric CO2 levels will exceed 500ppmv by the middle of this century and ~700 ppmv by 2100. Such atmospheric CO2 concentrations last occurred during “greenhouse” climates of the Cenozoic, for example during the Pliocene, mid-Miocene and early Eocene. The early Eocene was the warmest of these periods, characterised by polar regions far warmer than pre-industrial, reduced latitudinal temperature gradients, very small planetary ice volumes and much higher sea-levels than present.
Since participating on Integrated Ocean Drilling Expedition 318 I have worked on projects which: a) produced seasonal temperature reconstructions from the early Eocene greenhouse world on Antarctica and; b) linked Eocene cooling on the Antarctic to the initiation of ocean current flow across the Tasmanian Gateway. I am now working with colleagues in Birmingham, New Zealand, China and internationally, to improve our understanding of how Earth system processes operate under acute climatic warmth. We are addressing critical data-gaps on the availability and accuracy of pCO2 and temperature (SST) estimates. Uncertainty in these estimates stems from both the variable preservation quality of substrates used for geochemical analysis (calcareous shell material; organic biomarkers) andthe assumptions of individual proxy methodologies.
James Bendle 