Beyond national averages: a multi-method assessment of sub-national environmental sustainability and inequality in India

India’s rapid economic growth regularly jeopardizes its environmental foundation, although important sub-national differences were typically hidden by national-level evaluations. For all 37 Indian states and union territories (UTs), this study creates the Composite index of Environmental Sustainability (CoES), a comprehensive multi-dimensional framework that integrates 36 indicators across 4 sub-indices: climate-energy, terrestrial-biodiversity, waste-pollution, and water-sanitation sectors. We employ an innovative multi-method approach, including correlation analysis, network analysis, hierarchical clustering, inequality metrics, spatial additive decomposition, and hierarchical clustering. Results reveal a distinct ‘prosperity-pollution’ paradox, where high agricultural yields in the northern plains were statistically tied to extreme groundwater depletion and land degradation. Industrial wastewater compliance emerged as a ‘master connector’, bridging terrestrial health with sanitation infrastructure. While the Northeast leads in biodiversity wealth, significant infrastructure deficits in waste processing offset these ecological gains. Although Chandigarh emerges as the national standard for sub-national sustainability, inequality indices reveal a large disparity in forest cover and renewable energy infrastructure. We conclude that without density-focused management, increasing the area of forests is not enough to mitigate climate change. We offer context-specific policy recommendations that integrate climate-energy, biodiversity, waste-pollution, and water-sanitation concerns based on our empirical findings.