Does deglaciation mean less water available?
• The Himalayan glaciers provide the headwaters of ten major rivers in Asia. The glaciers store the water from the time of precipitation in the form of ice and release it slowly over time. The glacier contribution to river flow is most important in the dry season when there is no rainfall and in areas of generally low precipitation. The amount of meltwater depends on the mass of ice available for melting. In the early stages of deglaciation, more ice will melt and there will be more water in the rivers. As the glaciers reach a new equilibrium with a smaller overall mass, melting will be reduced. The timing and quantity of these changes is highly uncertain and needs more research. Changes in water availability will be most important in those river basins where the contribution of meltwater runoff is significant. • Changes in precipitation from snowfall to rainfall (as temperature increases) do not mean that there will be changes in overall (annual) water availability, rather that water
