DOES CLIMATE CHANGE AFFECT SUICIDE RATES?

(Image by Sol Haro Rivas)

Weather conditions and climate affect our mental health and also influence the population’s suicide risk

This summer, various media outlets published alarming headlines: that the summer of 2024 has been the hottest on record worldwide; that storms have fiercely battered different parts of the planet; that in August alone, ocean warming and the loss of sea ice at the poles increased; and that wildfires have intensified. New terms like anthropogenic climate change (climate change caused by human activities), eco-anxiety (an emotion associated with a changing and uncertain environment), ecological grief (the sorrow caused by ecological loss), and solastalgia (feeling homesick when witnessing distressing changes in one’s environment) are starting to be used, as all these extreme changes in weather patterns, along with air pollution, are not isolated or anecdotal incidents. Predictions suggest that climate change will worsen the situation in the coming years (WHO, 2022). Moreover, these events pose a significant threat to our physical health, increasing the risk of infectious, allergic, metabolic, neoplastic, respiratory, and cardiovascular diseases (Abbasi et al., 2023). Climate change is expected to cause many more heat-related deaths in Europe than those prevented by a reduction in cold (van Daalen et al., 2022).

But how might climate change affect mental health? A very recent scientific review conducted by researchers at Barcelona's Hospital Clínic and IDIBAPS analyzed 285 studies from around the world and found recurring patterns and associations: pollution impacts mental health (Radua et al., 2024).

And what about suicide? Suicide is a complex, multifaceted, and devastating phenomenon. Science has already shown that personal, social, and cultural factors play a role, but there is now new evidence that daily changes in weather conditions, especially temperature, influence suicide risk and attempts (Frangione et al., 2022). These authors conducted a systematic review and meta-analysis of studies examining daily or weekly variations in various weather variables related to suicide deaths or attempts and found a general increased relative risk of suicide deaths/attempts with a rise of just one degree in ambient temperature. The strongest associations were found in the East Asia and Pacific region, with men being at higher risk.

These findings are consistent with those of the Hospital Clínic researchers: there is a mild association between exposure to rising temperatures, suicidal behavior, suicide mortality, and emergency room visits (Radua et al., 2024).

What are the biological mechanisms behind this link between suicide and temperature? Some evidence suggests that high temperatures can directly affect brain function, altering proper oxygenation and the permeability of the blood-brain barrier. Other studies consider the alteration of neurotransmitters, or that higher temperatures may worsen mood, leading people to feel more irritable and stressed, amplifying symptoms of mental disorders (Radua et al., 2024; Aguglia et al., 2021). Furthermore, heat can lead to functional hypothyroidism, manifesting as decreased energy, dysphoria, cognitive impairment, difficulty concentrating, and irritability (Crane et al., 2022).

Additionally, other studies indicate that airborne particles such as ozone, sulfur dioxide, and nitrogen oxide are linked to a direct risk of suicide, with the proposed physiological mechanism being neuroinflammatory (Crane et al., 2022).

The increase in disasters associated with climate change, along with the consequences for human populations (migration, poverty, deaths…), also indirectly fuel the phenomenon of suicide (Crane et al., 2022).

Global warming adds yet another layer to the complexity behind a death by suicide. As a society, we will need to prepare for these circumstances that will shape a new reality. Governments will need to act to address this public health emergency, and scientific knowledge must outline the pathways for understanding the mediators and mechanisms of interaction between climate, mental health, and suicide.

References:

World Health Organization. Mental health and climate change: policy brief. Geneva: World Health Organization, 2022.

Abbasi, K., Ali, P., Barbour, V., Benfield, T., Bibbins-Domingo, K., Hancocks, S., ... & Zielinski, C. (2023). Time to treat the climate and nature crisis as one indivisible global health emergency. The Lancet, 402(10413), 1603-1606.

Radua, J., De Prisco, M., Oliva, V., Fico, G., Vieta, E., & Fusar‐Poli, P. (2024). Impact of air pollution and climate change on mental health outcomes: an umbrella review of global evidence. World Psychiatry, 23(2), 244-256.

Frangione, B., Villamizar, L. A. R., Lang, J. J., Colman, I., Lavigne, E., Peters, C., ... & Villeneuve, P. J. (2022). Short-term changes in meteorological conditions and suicide: A systematic review and meta-analysis. Environmental research, 207, 112230.

van Daalen, K. R., Romanello, M., Rocklöv, J., Semenza, J. C., Tonne, C., Markandya, A., ... & Lowe, R. (2022). The 2022 Europe report of the Lancet Countdown on health and climate change: towards a climate resilient future. The Lancet Public Health, 7(11), e942-e965.

Aguglia, A., Giacomini, G., Montagna, E., Amerio, A., Escelsior, A., Capello, M., ... & Amore, M. (2021). Meteorological variables and suicidal behavior: air pollution and apparent temperature are associated with high-lethality suicide attempts and male gender. Frontiers in psychiatry, 12, 653390.

Crane, K., Li, L., Subramanian, P., Rovit, E., & Liu, J. (2022). Climate change and mental health: A review of empirical evidence, mechanisms and implications. Atmosphere, 13(12), 2096.