With the rise in global temperatures due to climate change, heatwaves are predicted to become more frequent, prolonged, and intense. Safeguarding people's health, well-being, and quality of life from the effects of climate change and its extremes is now a priority for policymakers and international and national governments. High-risk areas, zones, districts, and communities must be recognized ahead of time to better guide planning and preparedness. This study focused on assessing the heatwave occurrence and developing a heatwave health risk index (HHRI) at the district level in Karnataka.

A comprehensive framework by the Intergovernmental Panel on Climate Change on a climate change risk assessment methodology incorporating hazard, exposure, and vulnerability was employed to develop the HHRI under the current climate change scenario. Among the crucial determinants influencing the HHRI, 11 indicators were selected, encompassing heatwave occurrence, diurnal temperature ranges, population density, outdoor labor population, population commuting on foot, number of medical institutions, green cover, elderly population, people with disabilities, multidimensional poverty index, and health index.

The districts with higher hazard, exposure, and vulnerability were identified and mapped along with their risk driving key factors. Among the 31 districts examined in our study, Bidar, Kalaburagi, Gadag, and Dharwad districts were classified in the very high-risk category, whereas 9 were classified in the high-risk category.

The study findings on the variations in heatwave health risks among districts will enable policymakers to prioritize and execute targeted strategies to successfully reduce climate impacts.