The Global Mental Health Burden of Historical Climate Change

Study Context

Nearly 80% of suicide deaths occur in low- and middle-income countries (World Health Organization et al., 2014). Despite the prevalence, the understanding of the many interacting drivers of suicide is relatively weak. Based on previous literature on a link between warming temperatures and rising suicide rates, the research team will use a newly-compiled, globally-comprehensive dataset to empirically quantify and separately identify both possible links between suicide and climate. Additionally, high-resolution climate model output from the “Detection and Attribution Model Intercomparison Project” (DAMIP) will be used to run counterfactual predictions in which the historical influence of anthropogenic emissions on global temperatures is removed. This project assembles, to our knowledge, the largest dataset of harmonized subnational suicide records ever compiled in order to: (i) comprehensively assess temperature’s influence on suicide at a global scale; (ii) identify the mechanisms linking changes in the climate to shifting patterns of self-harm; and (iii) quantify the effects of historic anthropogenic emissions on spatio-temporal patterns of suicide rates using an ensemble of climate models.

Study Design

Using annual national-level suicide records from the World Health Organization for 183 countries, this study will explain differences across populations in vulnerability to the mental health implications for climate change. It will also identify the channels through which higher temperatures may lead to suicide rate increases. Standard climate economic regression models will identify heterogeneity in the sensitivity of suicide rates to weather based on climate and socioeconomic conditions. Empirical results will be used to assess the spatially differentiated impact of anthropogenic climate change on suicide rates to date.

Results and Policy Lessons

The team’s empirical estimation uncovers a substantial positive impact of temperature on the rate of suicides that is robust across diverse global regions. These findings build on a few empirical studies similarly recovering suicide-temperature relationships in individual cities or countries. Specifically, the research team find that a one-degree Celsius rise in temperature increases the monthly suicide rate per 100,000 people by 0.005 to 0.012, depending on the country analyzed. These impacts represent a 0.6-1.3% increase in national average monthly suicide rates per 1 degree C, consistent with prior evidence from India, Mexico, and the United States. They find gender and age heterogeneities of responses, with male suicide rates exhibiting greater sensitivity to temperature variations compared to females. Furthermore, individuals aged 65 or older demonstrate a higher response rate. This pattern remains consistent and robust across multiple nations.