The Cryosphere Discussions www.the-cryosphere-discuss.net 1994-0432 1994-0440 3 3 2009 10.5194/tcd-3-947-2009 http://www.the-cryosphere-discuss.net/3/947/2009/ http://www.the-cryosphere-discuss.net/3/947/2009/tcd-3-947-2009.html http://www.the-cryosphere-discuss.net/3/947/2009/tcd-3-947-2009.pdf 947 993 2009-11-13 Response of the ice cap Hardangerjøkulen in southern Norway to the 20th and 21st century climates R. H. Giesen r.h.giesen@uu.nl J. Oerlemans Institute for Marine and Atmospheric research Utrecht, Utrecht University, P.O. Box 80005, 3508 TA Utrecht, The Netherlands Glacier mass balance changes lead to geometry changes and vice versa. To include this interdependence in the response of glaciers to climate change, models should include an interactive scheme coupling mass balance and ice dynamics. In this study, we couple a spatially distributed mass balance model to a two-dimensional ice-flow model and apply this coupled model to the ice cap Hardangerjøkulen in southern Norway. The available glacio-meteorological records, mass balance and glacier length change measurements were utilized for model calibration and validation. Driven with meteorological data from nearby synoptic weather stations, the coupled model realistically simulated the observed mass balance and glacier length changes during the 20th century. The mean climate for the period 1961–1990, computed from local meteorological data, was used as a basis to prescribe climate projections for the 21st century at Hardangerjøkulen. For a projected temperature increase of 3°C from 1961–1990 to 2071–2100, the modelled net mass balance soon becomes negative at all altitudes and Hardangerjøkulen disappears around the year 2100. The projected changes in the other meteorological variables could at most partly compensate for the effect of the projected warming. 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