Background

Extreme heat events are increasing in severity, duration, and frequency due to anthropogenic climate change.^{Reference Masson-Delmotte, Zhai and Pörtner1} This trend is expected to continue even in a best-case scenario of emissions reductions, but if emissions continue to rise in line with current trends, unusually extreme heat events will become a yearly phenomenon.

The impact of extreme heat events on health is well-documented across a range of settings. In Australia, heatwaves are responsible for more deaths than all other climate-related disasters combined.^{Reference Coates, Haynes and O’Brien2} Extreme heat events are associated with increased health service utilization, including emergency department visits, hospital in-patient admissions, and urban ambulance call-outs.^{Reference Gronlund, Zanobetti and Schwartz3–Reference Zhan, Yu and Qian8}

There is no consensus definition of an extreme heat event. The Australian Bureau of Meteorology (BoM; Melbourne, Victoria, Australia) defines a heatwave as a three-day period where both maximum and minimum temperatures are unusually hot compared to the normal local climatic conditions.⁹ However, in many parts of Australia, particularly northern Australia, heat is seasonal and extreme temperatures can last months.

Severe heat exposure can cause morbidity and mortality directly via heat-related illness, or more commonly indirectly through exacerbation of underlying chronic disease. Those with medical comorbidities, particularly cardiorespiratory,^{Reference Cheng, Xu and Bambrick10} renal,^{Reference Wang, Liu and Ye11} and mental illness,^{Reference Thompson, Hornigold and Page12} are at increased risk of morbidity and mortality during extreme heat events. Therefore, there is an imperative for health services to urgently undertake further research on how heatwaves will impact on service delivery.

Natural tolerance for environmental heat falls within a narrow temperature range. Adaptive responses to heat include physiological, behavioral, and sociocultural interventions including infrastructure such as the provision of environmentally cool spaces. Due to poor quality housing and energy insecurity, environmental cooling is not an option for everyone, contributing to the disproportionate effect of extreme heat events on people suffering socioeconomic disadvantage.^{Reference Benmarhnia, Deguen and Kaufman13}

Most literature addressing the links between heat and health is focused on urban environments. Rural and remote environments present different challenges in a number of ways. Firstly, rural and remote communities frequently have increased rates of chronic disease and socioeconomic disadvantage compared to their urban counterparts, making these populations potentially more vulnerable to extreme heat events. Secondly, rural and remote health systems often have limited resources, and thus may be overwhelmed by even a small increase in demand during heat events. Lastly, the impact of extreme heat events shows geographical and climatic variation^{Reference van der Linden, Longden and Richards14} with higher health burdens experienced in hotter climates where there is greater extent of hot weather.^{Reference Longden15} While there is a recognized “urban heat island effect” which tends to make densely populated urban areas warmer than the surrounding countryside, many major urban centers in Australia are located in temperate, coastal regions. Rural and remote regions are spread across the full range of climatic zones in Australia, including hot arid and tropical areas where baseline temperatures already approach the limits of human physiological adaptation, meaning that small increases may be more keenly felt.