An assessment of long-term changes in mortalities due to extreme weather events in India: A study of 50 years' data, 1970-2019

In the Indian subcontinent, the annual average extreme weather events (EWEs) are reported to be increasing during the last few decades. The impact of increased EWEs on mortality has become a key issue in terms of minimizing it, even with the increasing population. In the present study, based on 50 years' data (1970-2019) of India Meteorological Department, mortality rates of different EWEs viz., floods, tropical cyclones, heat waves, cold waves, lightning, etc. were analysed, both at the national and state level. The analysis was done based on different periods, i.e. annual, decadal and twenty-year slice periods. Various statistical analyses were carried out. Out of these EWEs, floods accounted for maximum mortality of 46.1%, followed by tropical cyclones with 28.6% mortality. Over the decades, despite a significant rise in EWEs (except for tropical cyclones), there has been a decrease in the mortality rate (mortalities per year per million population). The number of mortalities per event had a significant negative trend for heatwaves and floods, during the last 50 years. The total EWEs had a mortality rate of 3.86 during 1980-1999 and it reduced to 2.14 during 2000-2019. The mortality rate of tropical cyclones reduced by 94% in the past 20 years, whereas for heatwaves and lightning it increased by 62.2% and 52.8%, respectively. However, the change in mortality rate was not found to be statistically significant due to high year to year variability in mortality associated with floods, lightning, and tropical cyclones in the last two decades as compared to earlier decades. In India, among the major states, Odisha, Andhra Pradesh, Assam, Bihar, Kerala, and Maharashtra were found to be having maximum mortality rates due to EWEs in the last two decades and thus there is a need to consider these states with priority for developing disaster management action plans.

Automated summary

The study in the Indian subcontinent shows that annual average extreme weather events (EWEs) have been increasing in the last few decades, with floods and tropical cyclones causing the highest mortality rates. Despite the rise in EWEs, the mortality rate has decreased, except for tropical cyclones. The mortality rate has significant negative trends for heatwaves and floods over the past 50 years.