Rising urban land surface thermal extremes in a rapidly evolving tropical Indian state

Abstract

India, as a developing country is undergoing accelerated urbanization. However, this rapid and often unplanned urban growth has become a major concern as it significantly alters land surface characteristics. This leads to increased land surface temperatures (LSTs) which contribute to deteriorating air quality, energy overconsumption, and adverse health conditions, posing substantial challenges to sustainable urban climate management. The current study focuses on the identification and analysis of the evolution of thermal hotspots across 30 districts of Odisha, a rapidly developing tropical Indian state utilizing 20 years of datasets from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua, and Sentinel-2 satellite missions for the pre-monsoon season from 2017 to 2023. The analysis revealed that built-up areas exhibited significantly higher hotspot intensities than non-built-up regions. Districts with rapid population and industrial growth with extensive impervious surfaces and reduced vegetation showed a marked increase in thermal hotspots (at a maximum rate of 9% per year) emphasizing the role of impervious surfaces in modulating surface temperatures. In contrast, the percentage of hotspot coverage was higher over non-built-up areas for predominantly agrarian and semi-arid districts, likely due to the progressive decrease in vegetation cover from anthropogenic activity and consequent exposure of bare land. Furthermore, analysis indicated an intense prevalence of hotspots in rapidly urbanizing coastal districts with a minimum (maximum) increase of 2% (9%) area of hotspots in just seven years. These findings highlight the critical need for targeted mitigation strategies in urban areas facing intensified thermal stress.