Enhanced heatwaves exacerbate survival risks for vulnerable populations

Abstract

Extreme heat events are increasing under climate change and have been linked to adverse mental-health outcomes. However, evidence connecting heat exposure with suicide is largely based on short-term studies within individual countries, limiting understanding of global patterns and social disparities. This study examined associations between heatwave temperature anomalies and suicide mortality across countries with different socioeconomic contexts. We conducted a country-level panel analysis using harmonized suicide mortality records from the World Health Organization for 99 countries from 2000 to 2019, combined with gridded climate reanalysis data. Population-weighted country-year indicators of heatwave apparent temperature anomalies were linked to national suicide rates. Heatwave temperature anomaly is defined as the deviation of heatwave-day apparent temperature from the long-term (1990–2019) local climatological mean, capturing the intensity of extreme heat relative to local climate conditions. Poisson fixed-effects models estimated associations while accounting for country characteristics and long-term trends. Stratified analyses assessed heterogeneity by gender, age group, and socioeconomic vulnerability, and exploratory analyses examined national patterns of mental disorder burden. Higher heatwave apparent temperature anomalies were associated with increased female suicide mortality in middle-income countries. An 1 °C increase in apparent temperature during heatwaves corresponded to a 2.3% rise in female suicide rates. Associations were strongest among women aged 45–64 years and in countries with higher levels of vulnerable employment, representing approximately 0.33 billion and 0.24 billion people globally. National patterns of bipolar disorder burden were consistent with a potential mental-health pathway linking heat exposure and suicide vulnerability. These findings suggest that extreme heat may influence population-level suicide mortality, particularly in socially vulnerable settings, providing global empirical evidence supporting the association between heat exposure and suicide risk, and highlighting the need for integrated heat-adaptation and suicide-prevention strategies.