Journal of Glaciology, Vol. 57, No. 206, 2011 1033 Modelling the retreat of Grosser Aletschgletscher, Switzerland, in a changing climate Guillaume JOUVET,1,2 Matthias HUSS,3 Martin FUNK,4 Heinz BLATTER5 1Mathematics Institute of Computational Science and Engineering, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland 2Department of Mathematics and Computer Science, Free University of Berlin, D-14195 Berlin Dahlem, Germany E-mail:
[email protected] 3Department of Geosciences, University of Fribourg, CH-1700 Fribourg, Switzerland 4Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Z¨urich, CH-8092 Z¨urich, Switzerland 5Institute for Atmospheric and Climate Science, Universitatsstrasse¨ 16, ETH Z¨urich, CH-8092 Z¨urich, Switzerland ABSTRACT. For more than a century Alpine glaciers have been retreating dramatically, and they are expected to shrink even more quickly over the coming decades. This study addresses the future evolution of Grosser Aletschgletscher, Switzerland, the largest glacier in the European Alps. A three-dimensional combined surface mass-balance and glacier dynamics model was applied. The ice flow was described with the full Stokes equations. The glacier surface evolution was obtained by solving a transport equation for the volume of fluid. Daily surface melt and accumulation were calculated on the basis of climate data. The combined model was validated against several types of measurements made throughout the 20th century. For future climate change, scenarios based on regional climate models in the ENSEMBLES project were used. According to the median climatic evolution, Aletschgletscher was expected to lose 90% of its ice volume by the end of 2100. Even when the model was driven using current climate conditions (the past two decades) the glacier tongue experienced a considerable retreat of 6 km, indicating its strong disequilibrium with the present climate.