Response to ‘Thinking clearly about climate change and mental health’

Dear Editor,

It is disappointing that Australasian Psychiatry has published an article by its deputy editor without disclosing any conflict of interest, particularly as the article insinuates biased presentation of evidence in the RANZCP statement on climate change.^1,2

Amos’ article examined two of the 35 publications referenced in the RANZCP position statement ‘Mental health impacts of climate change’ and concluded that they were inadequate to support the statement. ¹ He noted that although 16 of 17 observational studies found positive relationships between higher temperatures and increased rates of suicide, observational research cannot prove that climate change increases suicide rates. ¹ However, the studies clearly demonstrate trends and provide adequate evidence for Thompson et al to support the assertion that rates of suicide are likely to increase in line with climate projections. The most recent data reviewed by Thompson et al is from 2012, and climate change and understanding of its impacts have accelerated since then. There is growing knowledge of the sociological, biological and psychological mechanisms by which climate change increases suicides. Thompson et al propose that public health authorities account for higher temperatures when they update suicide prevention strategies. ³ Similarly, the RANZCP statement notes that suicide, the most common cause of death of young Australians, is increasing, and action is needed. ²

Amos re-analysed data published by Burke et al that investigated associations between temperatures and suicide across the USA, ⁴ although they did not provide access to their statistical analysis. ¹ Amos used whole states rather than suburbs, and years rather than months as units of analysis, and this aggregated data showed an inverse relationship between temperatures and suicide rates. ¹ Aggregation masks the effects of extreme weather events that contribute to worsened health outcomes, and Amos’ finding does not undermine the evidence that climate change is increasing suicide rates. ⁴

Policy recommendations require critical analysis of evidence, and the RANZCP statement is based on peer-reviewed literature. Connections between climate change and mental health are complex, and on-going research is needed to understand causal relationships and reduce risk. However, the evidence is already sufficient for RANZCP to advocate for reducing its own contribution to climate change, and educating psychiatrists and the community. ²

Besides increasing suicide rates, climate change may also increase anxiety, depression, post-traumatic stress disorder, substance misuse and other mental health disorders. Addressing climate change, developing community resilience and supporting healthcare services to prepare for the increasing burdens of disease that climate change brings are urgent. ²