Relative importance of glacier contributions to streamflow in a changing climate

The role of glaciers and snow in climate change-affected runoff is evaluated by taking into account the carryover of runoff and of unmelted snow from one hydrological year to another. This water balance is computed for the present climate and for future climates with changed temperatures and precipitation. With this procedure, the contribution of glaciers to the total runoff and the yearly loss of glacier ice in a warmer climate can be more accurately determined than by just considering the overall increase of annual runoff volume. The Illecillewaet Basin in British Columbia, Canada (1155 km2, 509–3150 m a.s.l.) was selected for this study because of a significant glacial melt component in the runoff. For a temperature increase of 4°C, an additional 134.2•106m3 of today’s glaciers (in terms of water) in this basin would be melted in a year. This amount would be reduced as the glacier area gradually diminishes in the next decades.