Sector-specific clean water scarcity and competition under global change.

While the impact of future climate change on physical water availability has been extensively studied, the interplay with water quality and the associated impact on water scarcity-particularly the ensuing competition among sectors (domestic, irrigation, livestock, manufacturing, and energy) for clean water-is less well understood. Here we employed a globally applicable modelling framework to assess future cross-sectoral clean water gaps arising from competition for limited clean water resources, explicitly accounting for sector-specific water quantity and quality requirements under global change. Our results show that deteriorating water quality and insufficient water quantity will severely exacerbate future water gaps, exposing nearly 67% of the world's population to severe clean water gaps by 2100. As a result, cross-sectoral competition for clean water will greatly intensify, with disproportional impacts on the manufacturing and thermoelectric sectors, each facing a 20% increase in water gaps relative to their demands, primarily related to rising water temperatures. Overall, our findings underscore the need for integrated water management strategies that address both water quantity and quality to mitigate growing competition for clean water.