TONIC (Solving the Oligocene Icehouse Conundrum; 2022-2026; co-PI)
The climate of the Oligocene is a major puzzle. Sea level estimates suggest that the Antarctic Ice Sheet waxed and waned from periods of expansive ice sheets to intervals with very little ice. Current ice sheet models indicate that these large variations would require dramatic changes in the concentration of CO2, dwarfing those associated with the Pleistocene ice ages, and requiring release and sequestration of unprecedentedly large quantities of carbon by the deep ocean.
However, existing Oligocene CO2 reconstructions lack the resolution required to capture such changes, and furthermore reveal another puzzle: falling long-term CO2 levels with no corresponding change in climate. Either reconstructions of Oligocene CO2 - or climate and sea level - are inaccurate, or our understanding of ice sheet stability, climate sensitivity, and the carbon cycle needs to be fundamentally revised. This is the "Oligocene icehouse conundrum" that this proposal aims to solve.
This is a NERC Large Grant involving partners from University College London (Prof. Bridget Wade; Lead PI), University of Bristol and University of St. Andrews.