Antarctic ice and sediment flux in the Oligocene simulated by a climate–ice sheet–sediment model

Abstract A model of deforming sediment is added to a climate–ice sheet model, and applied to the Eocene–Oligocene transition in Antarctic ice volume around 34 Ma. The coupling between the global climate and ice sheet models is asynchronous, with a climate simulation performed once every 10 000 years, and only for the first 40 000 years. These global climate model solutions are re-used to perform runs of 400 000 years in length, with orbital forcing and different levels of CO2. The sediment model includes bulk transport under ice, generation of sub-ice till, and river transport, and predicts the continental-scale evolution of sediment thickness and coastal discharge. For the first few 10 000’s of years after the onset of substantial ice (triggered by CO2 falling below ∼3× pre-industrial level), sediment discharge to the ocean is relatively uniform around the coast, derived from nearby pre-existing regolith. After that, most discharge is concentrated into ∼4 sites at the mouths of major trough systems, with orbitally paced pulses on 104-yr scales. These sites and the average magnitudes of the fluxes agree generally with those deduced from offshore seismic and core data, although longer (10 my) integrations are needed to model the real sediment evolution.