The chronology of northern hemisphere ice-sheet extent during the last deglaciation is now fairly well known from glacial-geological observations. The thickness and volume of the ice sheets is however much harder to reconstruct from the geomorphological evidence and generally needs to be inferred from indirect evidence and modelling. One approach consists of glacio-isostatic modelling of relative sea-level changes in regions far away and in the vicinity of the former ice sheets to both determine the time-dependent change in global ice volume and the source contributions from individual ice sheets from some inverse modeling scheme. One problem is however that the resulting ice-sheet geometries are often at odds with the conventional understanding of ice dynamics. Here we report on another approach that aims to produce a glaciologically, climatologically, and geomorphologically consistent ice-loading history on the continents of the northern hemisphere since the LGM. We use a 3-D thermomechanical ice-sheet model applied to a northern hemisphere domain, which was upgraded from earlier versions to include more sophisticated mass-balance and glacial-isostatic components and a new treatment for marine calving. The climatic forcing was derived from a time-dependent experiment with the atmosphere/ocean/sea-ice model of intermediate complexity ECBILT/CLIO, which is fast enough to be able to model the period from LGM to present-day in a logistically reasonable period of time. Boundary conditions imposed on ECBILT/CLIO consist of changes in ice sheet area (albedo), ice sheet elevation, solar insolation and greenhouse gas concentrations. We expect that using the resulting ice loading histories as input in visco-elastic earth models may put better constraints on postglacial rebound and current rates of land uplift.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > MAR2-Palaeo Climate Mechanisms and Variability