Rift Propagation for Ice Sheet Models

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Modelled projections of the contribution of the Antarctic ice sheets to sea level rise over this century vary from a few centimetres to more than one metre - a huge uncertainty which undermines the credibility of sea level rise projections. The reasons for this uncertainty lie in the treatment of ice shelves - the floating extensions of ice sheets which constrain the flow of ice from the interior to the ocean. Assuming that ice shelves will disintegrate leads to a much higher estimate of ice discharge than assuming they remain in place. No forecast so far, however, has included the processes of ice fracture and rift propagation that lead to ice shelf disintegration. These processes disrupt the normal assumptions of continuity inherent in ice sheet models and are highly dependent on the heterogeneous nature of ice shelves. We will overcome this fundamental limitation in sea level rise projections by explicitly representing heterogeneity in ice shelves and pioneering the inclusion of rift processes in an ice sheet model. We will meet these challenges by collecting new field and satellite data to quantify ice shelf heterogeneity and developing a fracture physics approach to simulate rift propagation. RIPFISH will enable a new generation of ice sheet models to achieve a step-change improvement in quantifying and reducing uncertainties in sea level rise projections.