The impacts are there already. These are representative images from Central Ladakh from ‘69, ‘79, ’89; they show the cover of snow and, in fact, glacier ice. The reason why that’s important is that during the dry season something like 80% of the flow of the rivers of the great north Indian plain, the Indus, the Ganges, the Brahmaputra, about eighty per cent of that dry season flow comes from snow and melting glaciers. Already in the last fifteen years we’ve seen dramatic reductions in dry season flow. Calculations by glaciologists now suggest that by 2050 most of the Himalayan glaciers will have gone and the impact on dry season flow of those great rivers will be dramatic in the extreme. They could be reduced between twenty and thirty per cent of their current dry season flow with devastating impacts on agriculture in both India and Pakistan and indeed, in Western China.
In his Oct 29, 2009 presentation, Boulton said that the 2050 forecast was for a 60-70% reduction in dry season flow of Ganges. A dig-here.