Understanding the heat-induced discomforts associated with changing local climate zones in indian cities

Rapid urbanization is making city residents increasingly vulnerable to heat-related discomfort due to the intensification of the Urban Heat Island (UHI) effect. The Local Climate Zone (LCZ) framework offers a more nuanced way to understand how different urban forms influence thermal conditions. In this study, geospatial techniques were used to map LCZs at a fine scale, assess their morphological characteristics using Sky View Factor (SVF), examine their spatio-temporal and directional changes in the Kolkata Metropolitan Area (KMA) from 2010 to 2023, and explore how residents experience heat exposure within these zones. Sixteen LCZ types were identified, grouped into building and land-cover categories. The findings show a clear shift toward denser built-up forms, particularly compact mid-rise (LCZ 2) and compact low-rise (LCZ 3), alongside a noticeable reduction in vegetated areas (LCZ A–D). Urban expansion has been most prominent in the south-central part of KMA, gradually extending northward and northeastward. Over time, mean land surface temperatures (LST) have increased, with particularly intense conditions observed in lightweight low-rise (LCZ 7) and heavy industrial areas (LCZ 10). Analysis of survey responses revealed that heat-related discomfort varies not only by temperature intensity but also by duration of exposure, highlighting the complex relationship between urban form and human thermal experience. Together, these findings suggest that ongoing changes in urban structure are contributing to rising thermal stress, especially in dense urban cores. The steady loss of vegetation reduces the city’s natural cooling capacity, potentially increasing health risks and deepening socio-spatial inequalities. Understanding how urban morphology shapes everyday heat exposure is essential for designing cities that are not only climatically resilient but also more liveable for their residents.