Modelling the response of glaciers to a doubling in atmospheric CO2: a case study of Storglaciären, northern Sweden |
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| Authors: | C Schneeberger O Albrecht H Blatter M Wild R Hock |
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| Institution: | (1) Swiss Federal Institute of Technology, Institute for Climate Research, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland E-mail: blatter@geo.umnw.ethz.ch, CH;(2) Stockholm University, Department of Physical Geography, S-10691 Stockholm, Sweden, SE |
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| Abstract: | To predict the evolution of glaciers in an enhanced greenhouse climate, results from a global climate model, a glacier melt/accumulation model, and a glacier flow model were combined. The method was applied to Storglaciären, a small well-studied glacier in northern Sweden. The difference between the present climate and a 2 × CO2 climate around the year 2050 was extracted from a model experiment with the ECHAM4-T106 high resolution climate model for time slices at present and in 2050, using prescribed boundary conditions of sea surface temperature and sea-ice distribution, which are derived from a lower resolution transient run of the ECHAM4-T42/OPIC-coupled atmosphere ocean model between present and 2050. The local climatic conditions on the glacier for 2050 were obtained by adding the modelled local climate changes to the observed local present-day climate. The combination of the comprehensive models presented offers a tool to test and calibrate simplified models which are applicable to a much larger sample of glaciers. For the region of Storglaciären, the GCM projected temperature is found to increase most strongly during the winter months, but also shows a warming during the transition from spring to summer, and again between summer and fall, thus extending the melt season by three to four weeks. Precipitation, on the other hand, decreases by approximately 5% during May to September while there is a stronger increase of approximately 14% for the rest of the year. The consequent increase in winter accumulation on Storglaciären is more than compensated by the increase in ablation during the melt season. The glacier flow model predicts a 300 m retreat of the glacier terminus by the middle of the next century, and a loss of 30% of the present ice mass. |
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