Changing Glaciers and Hydrology in Asia - Environmental Health at ...

EXECUTIVE SUMMARYThe United States Agency for International Development’s (USAID’s) Asia Bureau, with supportfrom the Global Health Bureau, conducted a series of stakeholder and expert dialogues in 2009with the Woodrow Wilson International Center for Scholars entitled “Asia’s Future: CriticalThinking for a Changing Environment.” The dialogues identified and explored issues that willshape conditions in Asia during the 21 st century. One of the issues identified was climate change,and Asia’s high-mountain glaciers were a focal point of discussions. The Asia Bureau realized aneed to understand better the science and implications of glacier retreat and to assist Missionsin planning and programming new funding that is targeted to address the impacts of glacier meltin the high mountains of Asia. USAID initiated a project, led and managed by CDM International,Inc., that undertook the following tasks:Review the science concerning glacier melt in Asia.Identify key glacier melt vulnerabilities in the Asia region.Identify organizations contributing to addressing glacier melt and its impacts in Asia.Develop strategic cross-sectoral responses to these vulnerabilities, including responsesthat provide multiple benefits.The geographic focus of this study is on the region of “High Asia” (see the map on the cover),sometimes referred to as the Greater Himalayan region, and the countries whose river watersflow from High Asia. High Asia includes the Himalaya, Hindu Kush, Karakoram, Pamir, and TienShan mountain ranges, where current glacier coverage exists.The Scientific PerspectiveAlthough the world’s glaciers have been retreating slowly since the Little Ice Age (approximately1650 to 1850), recent climate warming has accelerated the rate of retreat. However, glaciersystems at the highest elevations, 4000-7000 m – like those in High Asia – have not respondedto recent climate warming in the same way as lower elevation glaciers, simply because higherelevationglaciers currently remain below freezing during much of the year, even in the presenceof a warmer climate.Long-term, comprehensive data for the remote glacierized areas of the Himalaya do not exist,so rates of retreat are not known over the whole region. Field measurements are often, bynecessity, limited to a few local measurements on easily accessible glaciers, typically at the lowerelevations. More recently, measurements over larger areas are becoming available utilizingsatellite remote sensing—but often lacking historical baselines. Historical glacier data from theHimalaya and adjacent mountain ranges are limited mostly to terminus location measurements.These are problematic because they only show that the ice at the terminus is melting faster thanthe rate at which ice is being supplied to that location by movement (dynamics) of ice fromfurther upslope in the system. A glacier might gain total mass from one year to the next (fromincreasing amounts of snow arriving at the higher elevations), while the terminus, at the lowest1