Modeling of Pleistocene European Ice Sheets: Some Experiments with Simple Mass-Balance Parameterizations

Abstract

A vertically integrated ice-flow model suitable for use in climate studies is formulated. Large continental ice sheets may be characterized by two fundamental quantities: the height-to-width ratio, and the steepness of the edge. So it is natural to develop a model containing two parameters that can be chosen to give the right values of those characteristic quantities. The result is a model that is close to M. A. W. Mahaffy’s (Journal of Geophysical Research 81, 1059-1066 (1976)). The model is used to study glaciation in Europe. Dropping the level of zero mass balance creates small stable ice caps in the Alps and the Scandinavian mountains. If the drop exceeds 600 m (with respect to present-day conditions), the feedback between ice-sheet height and mass balance becomes dominating and the Fennoscandian Ice Sheet keeps growing. It does not reach an equilibrium state within 60,008 yr. An experiment simulating rapid onset of a glacial cycle shows that the growth of ice volume in Europe is smaller than that in northern America (J. T. Andrews and M. A. W. Mahaffy, Quaternary Research 6, 167-183 (1976)). After 10,000 yr, the volume of the Fennoscandian Ice Sheet (2 x lOI m”) is about half the volume of the Laurentide Ice Sheet. This leaves the “observed” sea-level lowering in the period 125,000-115,000 yr B.P. (estimates center around 50 m) unexplained.