The increasing risk of heatwaves to vulnerable populations in eastern Australia

Abstract Heatwaves have caused more fatalities in Australia than any other natural hazard, and their frequency is expected to increase due to anthropogenic climate change. This growing risk underscores the urgent need to evaluate and enhance adaptation strategies for heatwaves to protect vulnerable community members. This study investigates historical trends in heatwave characteristics across New South Wales (NSW), identifies regions with increasing exposure in recent decades, and assesses risks to vulnerable populations using a combined heatwave risk framework. Using 5 km gridded temperature data, the Excess Heat Factor (EHF) was calculated to assess heatwave duration, intensity, frequency, and seasonality of heatwaves annually from 1910 to 2020. The Mann-Kendall trend test was applied to detect spatiotemporal patterns and highlight “hot spots” of intensified heatwave activity. Heatwave hazard was integrated with population exposure and demographic vulnerability to construct a Combined Heatwave Risk Index at the Local Government Area (LGA) scale. Vulnerability was quantified using NSW Census data, focusing on LGAs with higher concentrations of older adults living alone and on low incomes, groups known to be particularly susceptible to extreme heat. Results reveal a significant increase in heatwave exposure along the eastern seaboard, southeast, central, northern, and far-west NSW over the past two decades (2003–2022). Emerging heatwave risks were particularly evident for vulnerable communities in the far-west Local Government Areas (LGAs), northern and western Sydney, the Central Coast, and Lake Macquarie. This analysis contributes to Sustainable Development Goal (SDG) 13, “Climate Action,” by providing critical insights into climate change-driven heatwave impacts. It also supports SDG 3, “Good Health and Well-being,” by informing strategies to adapt to heatwaves and safeguard vulnerable populations during these extreme events.