Climate-driven land transformation and fragmented urban greening in a coastal landscape

• Climate projections indicate warming-driven intensification of hydrological fluxes. • Built-up land expands continuously from 2000 to 2060 across the district. • Landscape metrics reveal increasing fragmentation of vegetation and cropland. • Reduced patch connectivity signals structural degradation of coastal landscapes. Coastal and near-coastal landscapes are increasingly shaped by the combined influences of climate change and anthropogenic pressures, yet their long-term structural implications remain insufficiently quantified for medium-sized districts. This study integrates climate projections, land use/land cover (LULC) modeling, NDVI trends, and landscape spatial metrics to assess multi-decadal landscape transformation in Pudukkottai District, Tamil Nadu, from 2000 to 2060. Climate scenarios indicate persistent warming, increasing rainfall and humidity, and modest rises in wind speed, collectively intensifying hydrological processes and altering land-use suitability. LULC projections reveal sustained expansion of built-up areas alongside contraction of agricultural land, grasslands, and wetlands, while tree cover and surface water bodies exhibit relative persistence. However, spatial metrics (patch density, mean patch size, effective mesh size, and landscape shape indices) demonstrate that gains in vegetation are largely fragmented, occurring through the proliferation of small, isolated patches rather than contiguous, well-connected green networks. Declining patch size and connectivity for tree cover and grasslands, combined with delayed but pronounced cropland fragmentation, indicate a qualitative degradation of landscape structure despite localized greening. Comparisons with Pacific and other coastal regions indicate that Pudukkottai follows a broader coastal trajectory characterized by incremental urbanization, fragmented greening, and increasing water-resource dependence. These findings emphasize that future sustainability hinges on spatial cohesion and functional connectivity rather than land-cover extent alone. Integrating climate-informed spatial planning is therefore critical for aligning regional development with ecosystem resilience and the Sustainable Development Goals.