Water stress evolution and redistribution pathways under global inequality in consumption.

Global water stress is intensifying alongside the expansion of goods and services consumption. Based on consumption-based water footprint (CWF) accounting for 188 countries from 1990 to 2020, this study reveals a persistent strong coupling between water consumption and economic growth. Global income inequality further exacerbates structural imbalances in water consumption and reshapes the spatial distribution of water stress through trade networks: while high-income countries reduce local stress, low-income countries are increasingly trapped in the dual challenges of water depletion and persistent poverty. Machine learning projections indicate that by 2090, global water demand will rise to 5868-10,653 km3, and the deficit will widen to 2108-5887 km3. Under the medium scenario, >53 % of the global population, mainly in low-income countries across Asia and Africa, will face high water stress. Based on the weighted transfer contribution ratio (WTCR) and the consumption-based water stress index (CWSI) dual indicator framework, this study comprehensively identifies future water risk and redistribution potential. Results show that although surplus water from redistributive contributing zones may be sufficient to offset shortages in systemic collapse zones before 2070, redistribution capacity declines significantly by 2090, threatening the structural stability of the global water security system. Effective global water governance must therefore promote equitable burden sharing and trade restructuring. In particular, high-income countries should assume greater environmental responsibility to support the integrated achievement of the Sustainable Development Goals (SDGs).