Climate change is usually discussed through visible disasters such as heatwaves, wildfires, droughts and floods. A new international study warns that one of its deadliest effects may be much harder to see: a gradual rise in suicide deaths associated with increasing temperatures.
Researchers analyzed daily temperature and suicide data from 751 locations across 26 countries, then combined those relationships with future climate projections. Their results indicate that temperature-related suicide mortality could increase in every region studied by the 2050s, with the largest rises expected in warmer parts of Central and South America, southern Europe, Southeast Asia and South Africa. The full peer-reviewed research is available through Nature Mental Health.
The findings do not mean heat is the sole cause of suicide, nor do they predict the exact number of future deaths. Suicide results from a complex interaction of psychological, biological, social, economic and environmental factors. The study instead suggests that rising temperatures may become an additional pressure acting on already vulnerable people and communities.
Researchers Examined 751 Locations Across 26 Countries
The study represents one of the largest international attempts to project how climate warming may affect suicide mortality.
Researchers used historical daily records of temperature and suicide deaths from locations across North America, Central and South America, Europe, East and Southeast Asia, Australia and South Africa. They then estimated how local temperature–suicide relationships might change under three future emissions pathways.
The projections compared conditions during the 2050s with a baseline from the 2010s. According to the University of Tokyo’s research summary, the analysis was performed separately for each of the 751 locations before the findings were combined into broader regional estimates.
The result was consistent in direction: temperature-associated suicide mortality increased in every region under every modeled climate scenario.
The size of that increase differed considerably, however. Geography, existing climate conditions, socioeconomic vulnerability and the local relationship between heat and suicide all affected the projected burden.
The Largest Increases Could Occur in Warmer Regions
Central America experienced the strongest projected rise under the highest-emissions scenario.
By the 2050s, the proportion of suicide deaths attributable to temperature was projected to increase by approximately 6.4 percent in Central America compared with the 2010s. Across all regions, the highest-emissions scenario produced increases ranging from about 1.2 percent in northern Europe to 6.4 percent in Central America.
South America, southern Europe, Southeast Asia and South Africa were also among the regions projected to experience relatively large increases.
These areas did not necessarily experience the greatest absolute temperature rise. Instead, their existing temperature–suicide relationships appeared more sensitive to additional heat.
Warmer regions may also have fewer resources available for adaptation. Limited access to mental-health services, unstable employment, agricultural losses, weak housing and inadequate cooling can all intensify the effects of extreme temperatures.
The study’s authors noted that several of the regions facing the largest projected increases also contain lower-income countries with more limited social and healthcare infrastructure.
Colder Regions Are Not Protected
The projected increases were smaller in northern Europe, North America, East Asia and Australia, but they were still meaningful.
Under the highest-emissions scenario, East Asia showed an estimated 2 percent increase in temperature-attributable suicide mortality by the 2050s compared with the 2010s. Northern Europe showed the smallest regional increase at approximately 1.2 percent.
Some colder regions are expected to warm more rapidly than tropical areas. North America and northern Europe, for example, were projected to experience temperature increases exceeding 2°C under the most severe scenario.
Their smaller suicide projections appear to reflect differences in how suicide risk responds to temperature rather than an absence of warming.
In several East Asian locations, risk increased as temperatures rose but later levelled off or declined slightly at the most extreme temperatures. Researchers suggested that populations accustomed to hot and humid summers may have developed some physiological, behavioural or social adaptation.
That possibility remains uncertain and requires further investigation. The University of Tokyo researchers emphasized that adaptation patterns could vary according to housing, culture, public-health systems and historical exposure to heat.
Why Higher Temperatures May Affect Suicide Risk
The study did not attempt to identify one single biological explanation.
Previous research has connected high temperatures with disrupted sleep, irritability, psychological distress and worsening symptoms among people with existing mental-health conditions. Heat can also place stress on the body, reduce concentration and interfere with emotional regulation.
The World Health Organization’s heat and health guidance states that heat extremes can worsen mental-health conditions in addition to increasing cardiovascular, respiratory and kidney-related risks.
Sleep disruption may be particularly important. Hot nights can prevent the body from recovering after daytime heat exposure, while repeated poor sleep can worsen depression, anxiety, impulsivity and emotional instability.
Temperature may also interact with medications. Some psychiatric drugs affect sweating, hydration or the body’s ability to regulate heat, potentially increasing vulnerability during extreme conditions.
These mechanisms remain under study. The association between heat and suicide should not be interpreted as proof that temperature directly causes an individual death.
Climate Change Can Increase Risk Through Social Pressures
Temperature is only one pathway connecting climate change and mental health.
Drought can destroy crops and household income. Floods can displace families, damage homes and separate people from community support. Wildfires may produce trauma, financial loss and long-term uncertainty.
Climate-related events can also increase food prices, unemployment, migration and conflict. Those stresses may worsen depression, anxiety, grief and feelings of hopelessness, particularly when people already lack access to support.
The WHO’s overview of climate change and mental health identifies emotional distress, anxiety, depression, grief and suicidal behaviour among the potential consequences of a changing climate.
The new study focused specifically on short-term temperature associations rather than the wider effects of disasters, displacement or economic disruption. Its estimates may therefore represent only one part of climate change’s possible influence on suicide.
The Study Used Important Simplifying Assumptions
The projections should not be read as exact forecasts.
Researchers assumed that populations would not adapt physiologically or behaviourally to higher temperatures. They also assumed no changes in population structure and no changes in baseline suicide rates through the 2050s.
Those conditions will not remain perfectly fixed.
Countries may expand mental-health services, improve cooling access, change urban design or introduce heat-warning programs. Suicide rates may rise or fall for reasons unrelated to climate. Populations will also age, migrate and change in size.
These factors could make future mortality lower or higher than projected.
The study also excluded large parts of Africa and the Middle East because reliable suicide data were unavailable. Even in countries with established reporting systems, deaths may be misclassified or underreported because of social stigma and legal restrictions.
The World Health Organization’s suicide data similarly warns that underreporting and misclassification are especially serious for suicide compared with many other causes of death.
Suicide Is Already a Major Global Public-Health Crisis
More than 720,000 people die by suicide every year, according to the World Health Organization.
Suicide was the third leading cause of death among people aged 15 to 29 in 2021, and approximately 73 percent of global suicides occurred in low- and middle-income countries.
Climate-related increases would therefore be added to an already substantial burden.
Even a relatively small percentage rise could represent thousands of additional deaths when applied across large populations. The effect may be especially serious in places where counselling, emergency services and psychiatric care are already limited.
The study’s reference to a “hidden” rise is important because these deaths may not be recorded as climate-related. A heatwave death involving heatstroke can sometimes be identified directly. A suicide occurring during or after a period of extreme heat is far more difficult to attribute.
As a result, climate change’s mental-health effects may remain less visible than its physical health consequences.
Heat Plans Should Include Mental-Health Protection
Public-health responses to heat often focus on older adults, outdoor workers and people with cardiovascular or respiratory illnesses.
The new findings suggest that mental-health risk should also be included.
Heat-warning systems could alert psychiatric services, crisis lines, community health workers and caregivers when temperatures reach dangerous levels. Hospitals and clinics could identify patients whose conditions or medications make them particularly vulnerable.
Cooling centres should be designed to support people experiencing psychological distress as well as physical heat illness. Affordable cooling, shaded public spaces and better-insulated housing may also reduce exposure.
Mental-health services should remain available during floods, fires and power outages, when climate disasters can interrupt transport, communication and medication access.
Climate mitigation also matters. The projected suicide burden increased as emissions and warming increased, meaning stronger reductions in greenhouse-gas emissions could lower future risk.
Climate Policy Is Also Mental-Health Policy
The study does not claim that climate change determines individual behaviour.
It shows that population-level suicide risk appears sensitive to temperature and that this burden may rise as the planet warms.
The largest increases are expected in warmer and often less-resourced regions, but no studied region was entirely protected. Even places with stronger healthcare systems could experience additional deaths unless prevention programs adapt to changing conditions.
Suicide prevention traditionally focuses on healthcare access, crisis support, social connection and restricting access to lethal means. Those measures remain essential.
The emerging evidence suggests that heat preparedness, housing, labour protections, disaster recovery and emissions reduction should also be considered part of suicide prevention.
Climate change affects lives in ways that are not always immediately visible. A gradual increase in temperature-related suicide deaths may be one of its most serious hidden costs.
