Rising temperatures and suicidal behaviour in children and adolescents

To the Editor

Suicide is the leading cause of death in 15- to 24-year olds in Australia (www.aihw.gov.au/reports/life-expectancy-death/deaths-in-australia/contents/leading-causes-of-death) and self-harm requiring hospitalisation is both indicative of significant mental distress and a risk factor for future completed suicide (Christiansen and Jensen, 2007). Rates of self-harm requiring hospitalisation in children and adolescents have risen most years and overall for the past decade in New South Wales (NSW), Australia (www.healthstats.nsw.gov.au/Indicator/men_suihos/men_suihos_comparison). The Intergovernmental Panel on Climate Change describes children as particularly vulnerable to impacts of anthropogenic climate change, including on mental health.

Cumulative evidence of associations between higher air temperature and suicidal behaviour has recently been published (Charlson et al., 2021; Lawrance et al., 2021). Air temperatures have risen in NSW over the past decade, and across Australia, maximum summer temperatures rose 1.54°C from 2000 to 2020, compared with 1981–2010 as a baseline (Zhang et al., 2020). Further rises in temperature over the next 30 years are now unavoidable (https://naturaldisaster.royalcommission.gov.au/).

Studies show a positive correlation between ambient temperature and number of emergency presentations for self-harm, strengthened at more extreme high temperatures, especially when adjusted for humidity to find the apparent temperature (Basu et al., 2017). Rates of hospitalisation for intentional self-harm in NSW appear to be rising more steeply in coastal regions of NSW, and higher humidity may be contributing.

Indeed, there are increased mental health admissions to hospital during heatwaves (Lee et al. 2018; Williams et al., 2012). Moreover, suicide deaths are significantly elevated in weeks with anomalously high temperatures (Parks et al., 2020) and across populations (Burke et al., 2018; Dixon et al., 2014).

In context of escalating presentations of children and adolescents to emergency departments with suicidal behaviour, the association of elevated temperatures with suicidal behaviour in children and adolescents requires dispassionate but urgent evaluation. Public policy to mitigate against rising temperatures due to anthropogenic climate change may be important in suicide prevention. At the same time, given the temperature rises expected over the next 30 years, we submit that clinical services ready themselves to respond to further increases in suicidal behaviour during spring, summer and heatwaves.