A Weak Precipitation Sensitivity of Glacier Runoff

Abstract

A clear understanding of the influence of glaciers on the climate sensitivity of catchment runoff is critical to unravel the ongoing and future changes in runoff regimes of glacierized catchments in a warming climate. We demonstrate that irrespective of the climate setting, annual glacier runoff is relatively insensitive to the precipitation variability. A temperature-dependent runoff from the glaciers and a precipitation-dependent runoff from the non-glacierized parts determine the climate response of the runoff of glacierized catchments at different time scales. The buffering effect of glaciers against extreme droughts and the multidecadal runoff peak in catchments with shrinking glaciers, both follow from the above properties of glacier runoff. The empirically observed “glacier-compensation effect” is caused by an inhibited (amplified) response of the catchment runoff to the interannual precipitation (temperature) variability due to the glaciers present in the catchment.