Mountain glaciers are indispensable suppliers of freshwater for human sustenance in extensive cold and arid areas of the world. Under global environmental changes, linking climate-related glacio-hydrological changes to regional socioeconomic development is pivotal to sustainability. However, a global assessment of the opportunities and risks associated with glacial meltwater changes and population dynamics remains to be conducted. In this study, the importance of glacier water resources (GWR) is first regionalized in terms of supplying potential and corresponding human dependence. Then, opportunities and risks associated with glacial meltwater changes and population dynamics between 1980 and 2100 are analyzed. The results reveal that GWR plays an important role in 40 important glacier-fed basins (IGFBs) in which a total population of 1217.3 million lived in 2015, and nearly half of the population lived under highly or extremely highly water-stressed conditions, with a water availability per capita of less than 500 m³ yr⁻¹. Both the service potential of glacial meltwater (SPGM) and the population in the IGFBs under all RCPs (Representative Concentration Pathways) and SSPs (Shared Socioeconomic Pathways) but SSP3 are expected to continue to rise for a certain period of time until their maximums are reached, beyond which they will gradually decline. However, there is a mismatch in the peak times between the SPGM and population developments, which leads to opportunities or risks, depending on the basin and time. Both opportunities and risks are the greatest in the Indus River basin, which serves as an example illustrating the consequences of the mismatch between meltwater and population dynamics. The increase in glacial meltwater in this basin can seasonally satisfy the basic needs of an additional 83.7 million people from the 1990s to the 2040s, but 129.1 million more people would be exposed to severe water scarcity due to the projected decrease in glacial meltwater and the population increase after the 2040s. Following the sustainable pathway (SSP1) can significantly reduce the risk of water shortage in South and Central Asia, and South America.

glacial water resources,population dynamics,opportunity and risk,climate change,sustainability