The Effect of Extreme Heat on Mental Health – Evidence from Australia.

Abstract

INTRODUCTION: Carbon emissions are warming our planet and harming human health. While assessments of warming effects on physical health are becoming well-established, there are few quantitative analyses of impacts on mental health – a core aspect of human wellbeing and, by 2030, the world’s leading cause of burden of disease. Our goals were to accurately quantify the causal effects of extreme heat on individual-level mental health and wellbeing in Australia, which has the world’s most variable climate, with a view to providing input data for climate change impact scenario modelling. METHODS: Matching the data for four domains of mental wellbeing – mental health, vitality, social functioning and role-emotional – from waves 9 and 10 of the Household, Income and Labour Dynamics in Australia (HILDA) Survey, with temperature from Gridded Daily Temperature Data from the Australian Government Bureau of Meteorology forms a two-wave unbalanced panel dataset (12,891 participants aged 15 and over; 22,476 observations). Fixed effects models were employed to quantify the impacts of heat on mental health correcting for potential bias caused by unobserved individual-level adaptive capacity. We also controlled for a wide range of confounders. RESULTS: Same-day extreme heat (defined as over 308C) led to a 0.086 (95% CI 0.138, 0.034, P<0.001) standard-deviation deterioration in mental wellbeing (a combined score for four domains) equivalent to the negative association between unemployment and mental wellbeing. The cumulative effects of heat remained significant up to three months. Heat effects were gendered (mainly affecting men’s vitality and women’s emotional roles); women were more vulnerable overall to heat impacts than were men. CONCLUSIONS: This study suggests extreme heat can be harmful to multiple aspects of mental health and wellbeing, particularly for women. It is essential to consider mental health when proposing adaptation strategies in response to climate change impacts. i64