Sensitivity Experiments with a Model of the Ice Age Cycle: The Response to Milankovitch Forcing

Abstract

We address the question of the extent to which a simple one-dimensional time-dependent climate model is able to explain the fluctuations of continental ice volume which have occurred during the last quarter of the Pleistocene epoch. The model includes explicit ice physics based on the Glen flow law and explicit glacial isostatic adjustment based on a realistic viscoelastic field theory. When the model is forced by the Milankovitch variations of insulation it delivers ice volume fluctuations which are very similar to those implied by the specmap δ¹⁸O record. In particular, the model appears capable of explaining the observed correlation between eccentricity and ice volume variations, the dominance of the 10⁵ year period in the power spectrum of the ice volume time series, and the thickness and latitudinal extents of the continental ice sheets which existed at Würm–Wisconsin maximum 18 000 years ago.