Impact of Global Warming on Water Cycle Changes in the Western Himalaya: A Review

The Western Himalaya, often termed the "Water Tower of Asia," is experiencing critical hydrological changes due to global warming. This review synthesizes current scientific knowledge on climate-driven alterations in the region’s water cycle, assessing impacts on ecosystems, agriculture, energy security, and local livelihoods. We conducted a systematic literature review of peer-reviewed studies (2000–2024) from Scopus, Web of Science, and regional databases, supplemented by case studies and observational/modeling data. Key themes include cryospheric loss, shifting precipitation, river flow variability, and hydrological extremes. Key findings indicate that (1) temperature increases (0.2–0.5°C/decade) have accelerated glacier retreat (up to 20–30% mass loss in some basins) and reduced snow cover (5–15% decline since 2000); (2) altered precipitation patterns have increased rainfall dominance, elevating flood risks while reducing groundwater recharge in arid zones; and (3) river discharge shows declining dry-season flows but higher peak flows, threatening water security for over 200 million downstream inhabitants. These findings underscore the urgent need for integrated, cross-scale strategies combining scientific innovation, indigenous knowledge, and adaptive policies to enhance resilience. We highlight critical gaps in high-altitude monitoring and call for transboundary cooperation to mitigate escalating climate risks. This systematic review uniquely contrasts Western Himalayan hydrology with that of the Central and Eastern regions and benchmarks policy gaps, offering a roadmap for climate-resilient water governance.