Population Exposure to Compound Precipitation-Temperature Extremes in the Past and Future Climate across India

Abstract This study explores the population exposure to an increasing number of hydroclimatic extreme events owing to the warming climate. It is well-agreed that the extreme events are increasing in terms of frequency as well as intensity due to climate change and that the exposure to compound extreme events (concurrent occurrence of two or more extreme phenomena) affects population, ecosystems, and a variety of socioeconomic aspects more adversely. Specifically, the compound precipitation-temperature extremes (hot-dry and hot-wet) are considered, and the entire Indian mainland is regarded as the study region that spans over a wide variety of climatic regimes and wide variation of population density. The developed copula-based statistical method evaluates the change in population exposure to the compound extremes across the past (1981-2020) and future (near future: 2021-2060 and far future: 2061-2100) due to climate change. The results indicate an increase of more than 10 million person-year exposure from the compound extremes across many regions of the country, considering both near and far future periods. Densely populated regions have experienced more significant changes in hot-wet extremes as compared to the hot-dry extremes in the past, and the same is projected to continue in the future. The increase is as much as six-fold in many parts of the country, including Indo-Gangetic plains and southern-most coastal regions, identified as the future hotspots with the maximum increase in exposure under all the projected warming and population scenarios. The study helps to identify the regions that may need greater attention based on the risks of population exposure to compound extremes in a warmer future.