Anthropogenic climate change worsened recent declines in freshwater availability in India

Abstract Despite formidable evidence of the role of anthropogenic greenhouse gas emissions in the Earth’s climate system, detection of anthropogenic climate change in Indian freshwater resources remains uncertain. This study investigated the link between the recent (1980–2020) decline in freshwater availability and anthropogenic climate change using formal detection and attribution analysis. Water availability, defined as the difference between precipitation ( P ) and evapotranspiration ( E ), is assessed using a simple yet efficient Budyko-based hydrological model. Using the Indian Institute of Tropical Meteorology Earth System Model which is tailored to perform well in simulating climate in this region, we demonstrate that observed water availability decline (−5.60 mm yr −1 , p < 0.001) falls decisively outside the range of natural climate variability (−0.50–0.48 mm yr −1 from 1000 control simulations). The spatial correlation between observations and historical simulations exceeds 99.7% of natural variability patterns, providing strong evidence for anthropogenic influence. States like Uttar Pradesh, Bihar, and West Bengal, home to one-third of the country’s population, show significant decreases in freshwater availability beyond those expected from natural climate variability alone and are consistent with anthropogenic climate change.