Spatiotemporal Assessment of Urban Thermal Discomfort in Kolkata, India: Insights From Cloud-Based Remote Sensing

Urbanization and climate change are intricately linked, significantly influencing local and regional thermal environments. Kolkata, a rapidly expanding metropolitan city in India, has witnessed substantial shifts in urban thermal dynamics due to increasing land surface temperatures (LST), the urban heat island (UHI) effect, and heightened thermal discomfort. This article integrates high-resolution remote sensing data and a cloud-based platform via Google Earth Engine to assess spatiotemporal changes in thermal discomfort in Kolkata. The article employs the urban thermal field variance index (UTFVI) to estimate the urban thermal discomfort, while the Sen’s slope estimator and the modified Mann–Kendall tests are applied to assess long-term spatiotemporal trends in urban thermal conditions. Findings reveal that LST, UHI, and UTFVI are significantly increasing at the rates of 0.149 °C/year, 0.041 °C/year, and 0.0041 °C/year, respectively. The results further reveal that those areas with low vegetation cover experience extreme thermal stress, highlighting the critical role of urban greenery in mitigating heat-related discomfort. The article offers data-driven insights into Kolkata’s urban thermal landscape, with guidance for policymakers in developing sustainable urban planning and climate adaptation strategies, such as expanding green spaces, implementing cool roof technologies, and enhancing urban ventilation. By leveraging cloud-based remote sensing, this article provides a scalable framework for assessing and addressing urban thermal discomfort in other rapidly urbanizing cities worldwide.