A new study has, for the first time in the world, quantitatively projected how climate change will affect mental health at a multi-country level. Applying future climate change scenarios, a KAIST research team found that temperature-related suicide mortality is expected to rise overall, with the scale of the increase varying by region.

KAIST (President Choongsik Bae) announced on the 10th of July that a joint research team led by Professor Yeonseung Chung from the Department of Mathematical Sciences and Professor Yoonhee Kim from the Department of Global Environmental Health, Graduate School of Medicine, at the University of Tokyo in Japan, analyzed daily suicide mortality and temperature data from 751 locations across 26 countries, and applied the latest climate change scenarios to project future temperature-related suicide mortality. The team found that temperature-related suicide mortality is expected to increase due to climate change, with the scale of the increase varying by region.

Climate change is increasing extreme weather events such as heat waves, floods, and wildfires, and is having a wide-ranging impact on human health. Recent studies have consistently reported that climate change affects not only physical health but also mental health, including depression, anxiety, and sleep disorders. In particular, the tendency for suicide risk to rise with increasing temperatures has been repeatedly confirmed across many countries, but few studies have quantitatively projected how future climate change will affect temperature-related suicide mortality.

The team explained that these regional differences are determined not only by the magnitude of future temperature increases, but also by each region's temperature–suicide relationship — how suicide risk changes with temperature. In East Asia, suicide risk was found to increase with rising temperatures, but the increase slowed at high temperatures, so the region's future rise in temperature-related suicide mortality is projected to be relatively small. Central and South America and Southeast Asia, by contrast, are projected to see relatively large future increases, driven by both greater projected temperature rises and a pattern in which suicide risk continues to climb steadily as temperatures rise.

The team pointed to a range of physiological and psychological changes — including sleep disturbances, increased stress, and impaired emotional regulation — as factors linking high temperatures to increased suicide risk. In particular, they explained that high temperatures can affect serotonin regulation and stress hormone secretion in the brain, potentially heightening depressive feelings and impulsivity, changes that may in turn contribute to increased suicide risk.

This study is significant as the first large-scale, multi-country quantitative projection of climate change's future impact on mental health. The findings show that climate change should not solely be considered an environmental issue but it should also be viewed from a mental health perspective, and they are expected to provide important scientific evidence for developing mental health policy and suicide prevention strategies in the era of climate change.

The team emphasized that reducing the future mental health burden of climate change will require strengthening heat wave response systems alongside expanded mental health services, protection for vulnerable populations, and suicide prevention policies tailored to regional climate characteristics. The team also said that it plans to conduct more refined future projection studies that account for demographic change, adaptation to high temperatures, and improvements in mental health services.

"We hope this research will be used to help prepare for the mental health burden of the era of climate change," said Professor Yeonseung Chung.

The study, with Hyeyeong Ro, a master's student in KAIST's Graduate School of Data Science, as first author, and Professor Yeonseung Chung from KAIST's Department of Mathematical Sciences and Professor Yoonhee Kim from the University of Tokyo as co-corresponding authors, was published on the 30th of June in the international mental health journal Nature Mental Health.

※ Paper title: "Multi-country projections of temperature-related suicide mortality"

※ DOI: https://doi.org/10.1038/s44220-026-00674-w