What do we know about the mental health effects of chronic, slow-onset climate change?

By Tarun Sai LomteReviewed by Danielle Ellis, B.Sc.Jan 23 2024

In a recent study published in Nature Mental Health, researchers assessed the effects of chronic climate change on mental health.

Background

The global concern about climate change and its impact on mental health is informed by years of research into the relationship between exposure to environmental disasters and mental health outcomes. Acute climate events have been linked to increased symptoms and cases of psychiatric disorders, negative emotions, behavioral indicators of poor mental health, non-specific psychological distress, and utilization of mental health services.

Climate change causes long-term changes in weather patterns, and communities are exposed to slow-onset conditions that evolve gradually from incremental changes over the years. These chronic climate conditions or slow-onset events include long-term changes in precipitation and temperature, soil degradation, and chronic drought. Their impact on mental health is less well characterized.

The distinction between slow- and acute-onset events is obscure. For instance, excessive precipitation could result in more acute flooding events involving both chronic and acute exposures. Despite the complexities, differentiating between the types of events is essential to conceptualize and study associations of climate change with health, as the effects of slow- and sudden-onset events will differ.

About the study

In the present study, researchers systematically reviewed the associations between slow, long-term climate change indicators and mental health outcomes. Studies discussing the association between chronic climate change and mental health outcomes were identified from Web of Science, Medline, PsycINFO, Global Health, Global Index Medicus, and CAB abstracts.

Qualitative, quantitative, and mixed-method studies were selected. Double-blind abstract screening was performed, followed by a full-text review. Included studies empirically assessed the association of mental health disorders and well-being with exposure to specific slow-onset, chronic climatic, and meteorological hazards associated with global warming and anthropogenic climate change.

The team considered three categories of mental health outcomes – 1) symptoms and cases of psychiatric disorders, 2) psychological indicators of mental distress and well-being, and 3) behavioral indicators linked to poor mental health. Studies on acute weather-related exposures, commentaries, reviews, animal studies, and gray literature were excluded. Five team members extracted data on key themes from each paper.

The risk of bias was assessed using several appraisal tools. The team classified an association as “positive” if slow-onset climate change was associated with a higher risk of adverse mental health outcomes, “negative” if the risk was reduced, “null” if findings were non-statistically significant, and “mixed” if positive, negative, or null associations were found or if the effects were heterogeneous.

Findings

The team initially identified 14,502 records, including 11,342 unique articles. Full texts of 603 articles were screened, and 57 studies were included in this review. Among these, there were 17 qualitative studies, 30 quantitative studies, and 10 mixed-methods studies. Most studies were conducted in North America, Europe, and Australia. Over one-third of studies were performed in Australia.

Eight studies were conducted in Canada and six in the United States. Five studies focused on Africa, and only one on South America. Among quantitative studies, over half of the associations were mixed or null, implying that although there was a positive association, the evidence was inconclusive, warranting additional investigation.

The team tabulated mental health terms identified in extracted themes from qualitative studies and noted two patterns. First, participants described diverse experiences and mental health conditions, such as negative emotions (worry, anxiety, grief, frustration, sadness, and concern). Further, participants also identified the targets or domains of the mental health conditions. The most frequent targets were concerns about the future, family, and community.

Conclusions

The researchers identified 57 studies assessing the relationship between mental health and chronic climate change. Findings revealed a small body of literature on chronic climate change compared to immense research on acute climate change. The most frequently assessed conditions were symptoms and cases of depression and anxiety, non-specific psychological distress, suicide, and negative emotions.

Although there was evidence linking chronic climate changes to adverse outcomes, numerous studies had mixed or null findings. Taken together, the findings highlight the need for more research on chronic climate change. Future quantitative research should examine (associations of chronic climate change with) the most frequent indicators identified in qualitative literature, i.e., negative emotions. Furthermore, studies are needed in understudied, at-risk areas, such as West Africa, South and Central America, and Southeast Asia.