Disappearance of an Alpine glacier over the 21st Century simulated from modeling its future surface mass balance

Abstract : A spatially-distributed snow/ice model is used to simulate the surface mass balance of the Saint Sorlin Glacier (French Alps) over the 1981–2004 period. The modeled mass balance globally reproduces field data except over places where, because of the scarcity of measurements, small-scale features as proposed by the model are smoothed out by the data interpolation. Both measured and simulated mass balance fields are then used to force a 2-D ice flow model and comparison of respective results show similar large-scale glacier flow dynamics. On the other hand, at a smaller scale, the present-day ice distribution computed from the modeled mass balance field sometimes deviates from that obtained with the interpolated field mass balance. It particularly offers a better match to observations by succeeding in reproducing a specific deglaciation pattern in the upper part of the glacier. These preliminary results led us to consider the possibility of substituting modeled mass balance series to measured ones, especially when modeling the future of the glacier. This latter approach is thus applied to simulate the glacier response under the IPCC SRESB1 scenario. Results show a rapid decay leading to a total disappearance of the glacier by the year 2070.