Decadal changes in the snow regime of high mountain Asia 1987 2016 More than a billion people rely on water from rivers sourced in High Mountain Asia (HMA) a significant portion of which is derived from snow and glacier melt. Rural communities are heavily dependent on the consistency of runoff and are highly vulnerable to shifts in their local environment brought on by climate change. Despite this dependence the impacts of climate change in HMA remain poorly constrained due to poor process understanding complex terrain and insufficiently dense in situ measurements. HMAs glaciers contain more frozen water than any region outside of the poles. Their extensive retreat is a highly visible and much studied marker of regional and global climate change. However in many catchments snow and snowmelt represent a much larger fraction of the yearly water budget than glacial meltwaters. Despite their importance climate related changes in HMAs snow resources have not been well studied. Changes in the volume and distribution of snowpack have complex and extensive impacts on both local and global ...