Mountain glaciers and water supply:
In glaciers and snow cover, precipitation is stored over months or years. Although mountain glaciers comprise only 0.1 % (vol.) of the worlds freshwater distributed in climate regimes from Alaska to New Zealand, they have a considerable effect on a reliable water yield. In the past, glacier melt not only contributed to water supply in arid regions, but also in the Alps during summer, where the influence of glacier melt on runoff is demonstrated for the river Rhine and the Vernagtbach stream.
A further shrinkage of glaciers and the reduction of snow cover leads to stream flow being primarily driven by rainfall and less by melting, resulting in a higher temporal and quantitative variability in discharge. Water shortages from missing glacier runoff will influence the economy of numerous countries.