Improved Outlook for Himalayan Water Supply
Ars Technica’s Scott K. Johnson reports that the effects of retreating Himalayan glaciers on China’s rivers this century may be fairly limited, offering some rare respite from a stream of bad news about the country’s water security.
Contrary to their earlier results, the researchers found no decrease in total water supplied to either of the [Indus or Ganges] rivers before the end of the 21st century. The glaciers retreated plenty (up to 60 percent of ice volume was lost by 2100), but the amount of glacial meltwater didn’t peak until roughly 2060 or so, after which it began a slow decline. Increasing precipitation, however, made up for some of that drop, preventing the total contribution to the rivers from decreasing.
[…] While the study only attempts to characterize the Indus and Ganges Rivers, there’s a good chance that its conclusions could extend to the Yellow and Yangtze Rivers as well. Although glacial melt provides a smaller portion of the rivers’ flow, precipitation is projected to increase over those glaciers, as well. Walter Immerzeel, a researcher at Utrecht University in the Netherlands involved in this study, told Ars that “a conclusive answer would require a similar modelling approach as [our study], as the runoff change also depends on intra-annual changes in precipitation and temperature and on changes in evapotranspiration.” [Source]