A One-Dimensional Model of Continental Ice Volume Fluctuations through the Pleistocene: Implications for the Origin of the Mid-Pleistocene Climate Transition

Abstract

Abstract A new one-dimensional, zonally averaged high resolution spherical model of the accumulation and flow of continental ice sheets in response to variations in insolation forcing has been constructed. The model includes a detailed representation of the influence of the isostatic adjustment of the earth under the weight of the ice at a rate determined by the viscosity of the planetary mantle. With this model we address the issue as to whether the combination of physical processes that it includes is sufficient to allow us to reconcile the variations of continental ice volume that are inferred to have dominated the Pleistocene epoch on the basis of the analysis of δ18O data from deep-sea sedimentary cores. We use high resolution data from the newly analyzed ODP site 677 and from DSDP site 607 as principal observational constraints. These datasets reveal a marked transition in climate to have occurred at mid-Pleistocene time about 900 000 years BP. In order to understand this transition, we find that we...