Climate Change and an Aging Society: The Rapid Increase of Heatstroke Deaths in Japan (1972-2022)

Kaoru Kakinuma, Shanghai University
Nozomu INOUE

As global temperatures rise, heatstroke mortality is becoming a major public health concern, particularly in aging societies. Japan, with one of the most rapidly aging populations and its detailed heatstroke mortality data, can provide crucial insights into how demographic and environmental factors increase vulnerability to heatstroke death. This study used individual-level death data (1972–2022), including age, gender, and location of death, from Japan's vital statistics to perform both individual- and municipal-level analyses. At the municipal level, we integrated heatstroke death counts, summer temperature anomalies, and the proportion of elderly residents to explore how demographic factors and climate conditions intersect. Results showed a significant increase in heatstroke deaths, rising from 42 in 1972 to 1,617 in 2022. When comparing deaths using the same ICD-10 code (T67), heatstroke deaths rose from 337 in 1995 to 1,617 in 2022. Additionally, spatio-temporal patterns in heatstroke mortality were identified. Japan’s experience provides valuable empirical evidence of the increase in heatstroke deaths, offering clear insights into how climate change directly affects mortality. This study highlights the importance of integrating the spatio-temporal distribution of elderly populations with regional temperature patterns to mitigate future heatstroke mortality risks.

Keywords: Population Ageing, Health and Morbidity, Spatial Demography, Population, Environment, and Climate Change

See extended abstract.