Light-absorbing impurities in snow and ice increase the absorption of solar radiation and thus enhance melting. We investigated the effect of Saharan dust and black carbon on the mass balance of an Alpine glacier over 1914-2014. Snow impurities increased melt by 15-19% depending on the location on the glacier. From the accumulation area towards the equilibrium line, the effect of impurities increased as more frequent years with negative mass balance led to a re-exposure of dust-enriched layers.