Linking climate change to self-harm: A global study of over 200 countries from 1990 to 2020

Climate change significantly affects both environmental and human health. A recent, comprehensive global overview of its impacts on mental health and self-harming behaviours is lacking, as well as detailed insights into the effects of potential confounders, including gender, age, socioeconomic factors and their potential interactions. Using a cutting-edge generalized additive model (GAM) framework, we analyzed multiple global datasets covering between 175 to 201 countries from 1990 to 2020. We found robust associations between self-harm incidence rates and major climate change parameters, including greenhouse gas emission and temperature change, as well as air pollutant particulate matter 2.5 (PM2.5) exposure, a critical contributor to climate change. Importantly, detailed analyses suggested that self-harm in young males had stronger links to climate change parameters than in young females, while the opposite gender associations were found later in life. Our global analyses provide important evidence on mental health consequences of climate change, instructive for developing appropriate population-based mental health strategies and climate policies and enhancing mental health services. This will contribute to improving human and planetary health.