• Climate change impacts on the cryosphere will impact the hydrological cycle and overall water availability in the HKH.
  
• Total water availability at higher elevations will increase until mid-century, with changes in the amount and timing of water flows posing a serious threat to people’s livelihoods, before decreasing from mid-century on.
  
• Snowmelt is responsible for most river flow of western HKH rivers, including 79% of the Amu Darya. The amount and frequency of snow fall has changed considerably and water runoff from snow has already fallen between 1979 and 2019 and is set to fall further, jeopardising the livelihoods of 129 million farmers in the Indus, Ganges and Brahmaputra basins.
  
• More erratic monsoons, also driven by climate change, are accelerating communities’ dependence on meltwaters that are set to decline.
  
• Springs, the main source of water for mountain communities, are mostly (83%) replenished through snowmelt and glacier melt. Decreasing melt will have dire consequences for the 240 million who live in the mountains.
  
• Climate has been a key driver in many of the water- and cryosphere-related disasters have been recorded in recent years, through meltwater, larger and more potentially dangerous lakes, unstable slopes from thawing permafrost, and increasing sediment loads in rivers.
  

• The retreat of mountain glaciers has increased the size and number of glacial lakes, and a three-fold increase in GLOF risk across the HKH is projected by the end of the twenty-first century, and it’s predicted we’ll reach ‘peak GLOF risk’ by 2050.
  
• There are 2,000+ glacial lakes in the region, of which 200+ are dangerous. The growth in the number and size of glacial lakes is set to continue – creating new hotspots of potentially dangerous glacial lakes, with implications for glacial lake outburst flood (GLOF) hazards and risk.
  
• Large avalanches of rock and/or ice are expected to increase in frequency and magnitude under a warmer climate, with recent deglaciation and or degrading permafrost and often unusually warm/wet conditions preceding a disaster – such triggers are expected to become increasingly prevalent and relevant over the coming decades.
  
• As hydropower and road infrastructure are increasingly being constructed in the upstream areas of watersheds, the risk of exposure to mass flow events is increasing.
  

• Governments should build a detailed understanding of water sources’ contribution to river flows to anticipate future changes and possible hazards and downstream water use.
  
• Not enough is being done to prepare for climate-driven multi-hazards and cascading event chains.
  
• Rising frequency and intensity of floods and droughts will drive increased dependence on meltwater – but better modelling of supply and demand is needed.
  

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