Abstract
The mountainous Third Pole is a critical source of freshwater for water resource management across Asia, yet the historical and future dynamics of per-capita freshwater supply in this region remain poorly constrained by observations from a coherent, pan-regional perspective. Here, we show that by the end of the 21st century, mountain runoff in the Third Pole’s monsoon domain will increase substantially, whereas runoff in the westerlies domain will experience a non-significant decline. This finding challenges the prevailing paradigm that future runoff across the entire Third Pole will follow a unidirectional increasing trend as future precipitation. Regarding long-term freshwater availability till the end-of-21-century (1960‒2100), although mountain runoff shows a contrasting pattern with increase (decrease) at first and then decrease (increase) in the westerlies (monsoon) domain, the per-capita freshwater supply (for mountain basins and their downstream dependent regions) drops a lot in both westerlies and monsoon domains from the past (1960‒1970) to the near future (2030‒2050) due to rapid population increase. These findings provide vital information to cope with fast-growing water demands and achieve Sustainable Development Goals.
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Data availability
The glacier datasets are available at https://www.glims.org/RGI. The ISIMIP3b data are available at https://data.isimip.org/. The historical and future population data are available at https://doi.org/10.7927/q7z9-9r69. Runoff observations are available from the hard copy of Chinese Hydrological Data Yearbook (that can be found National Library of China), Department of Hydrology and Meteorology in Nepal (DHM; http://dhm.gov.np), Pakistan Water & Power Development Authority (WAPDA; https://www.wapda.gov.pk), the Scientific-Information Center of the Interstate Commission for Water Coordination in Central Asia (http://isepei.org/organization/sic-icwc), as well as the Global Runoff Data Center (https://grdc.bafg.de).
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Acknowledgements
This research was supported by the Second Tibetan Plateau Scientific Expedition and Research Program (2024QZKK0400), the National Key R&D Program of China (2024YFF0808602), and Tsinghua University (100008001).
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L.W. designed the study and drafted the manuscript. L.W. and J.L. performed the data analysis. D.C., N.L., X.L., and T.Y. reviewed and contributed to the final form of the study.
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Author L.W. is Associate Editor and D.C. is Editorial Board Member of npj Climate and Atmospheric Science. Both L.W. and D.C. were not involved in the journal’s review of, or decisions related to, this manuscript.
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Wang, L., Long, J., Chen, D. et al. Divergent mountain runoff dynamics but declining per capita freshwater availability across the Third Pole by mid-21st century. npj Clim Atmos Sci (2026). https://doi.org/10.1038/s41612-025-01313-4
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DOI: https://doi.org/10.1038/s41612-025-01313-4
