Assessment of biophilic conditions through geo-statistical approaches for urban growth and vegetation loss in Kolkata Metropolitan Area

• Built-up areas in KMA increased from 21.97% in 1991 to 50.46% in 2025 and are projected to reach 65.41% by 2050, while vegetation declined from 26.08% to 6.33%. • Regression analyses confirm that urban expansion occurs at the cost of green cover, with R² values ranging from 0.30 to 0.48. • A core-to-periphery diffusion pattern is evident, with early-industrialised municipalities experiencing near-total vegetation depletion before 2000, while peri-urban zones underwent accelerated loss post-2001. • Per capita green space fell below the WHO's recommended minimum of 9 m² in most municipalities, signifying a metropolitan-scale biophilic deficit. • The findings underscore the need for nature-based solutions, blue-green infrastructure networks, and biophilic urban planning to restore ecological balance in the expanding KMA. The Kolkata Metropolitan Area (KMA) has experienced rapid urban expansion and ecological degradation over the past few decades, raising concerns about long-term urban sustainability. This study quantified land-use transitions, examined the relationships between urban growth and vegetation loss, and assessed the spatial gradients of ecological decline across the KMA using multi-temporal satellite data from 1991 to 2025, with land-use projections extended to 2050. The results indicate that built-up areas expanded from 21.97% in 1991 to 50.46% in 2025 and are projected to reach 65.41% by 2050, whereas vegetation cover declined sharply from 26.08% to 6.33% by 2050. Regression analysis revealed a consistent inverse relationship between urban expansion and vegetation loss (R² = 0.30–0.48), indicating that built-up growth explains a substantial, though not exclusive, portion of the decline in green cover, reflecting the influence of additional socio-spatial drivers. Spectral indices further corroborated this transition, with the Normalised Difference Built-up Index (NDBI) increasing from 0.26 to 0.55 and the Normalised Difference Vegetation Index (NDVI) declining from 0.68 to 0.43, indicating a shift from vegetated to impervious landscapes. The per-capita green space has fallen below the World Health Organisation recommended minimum of 9 m² in most municipalities. These trends indicate the emergence of a metropolitan scale biophilic deficit, characterised by ecological fragmentation, reduced ecosystem services, and declining resilience. These findings provide actionable insights for urban planners and policymakers, underscoring the urgency of integrating nature-based solutions, blue–green infrastructure (BGI) networks, and biophilic planning strategies to guide sustainable and climate-resilient urban development in the KMA.