Human Vulnerability to Heatwave in Australia: A country-wide Suburb level Longitudinal Study

BACKGROUND AND AIM: There is evidence of increasing heatwave-associated deaths and hospitalizations in Australia, particularly among older people. However, there is a lack of longitudinal studies investigating heatwave vulnerability in the context of Australia. Using longitudinal study design, we examined heatwave vulnerability at Statistical Area Level 2 geographical unit (referred to as suburbs) in Australia and identified the influential factors contributing to this vulnerability. METHODS: We obtained socioeconomic, demographic, and chronic disease variables from 5-year national Census estimates (2011, 2016, and 2021) provided by the Australian Bureau of Statistics. We included landcover (2003-2020) data from the Australian Bureau of Agriculture, Resource Economics and Sciences (ABARES), and heatwave data (2001-2020) from the Bureau of Meteorology into the analysis. We applied principal component analysis, ordinal logistic regression, and geospatial modelling techniques to develop the heatwave vulnerability index and determined influential factors of heatwave vulnerability. RESULTS: We found variability in heatwave-health vulnerability both spatially and temporally across Australia, with higher vulnerability particularly in the Northwest, and the lowest in Southeast Australia. The suburbs within greater cities had greater temporal changes in heatwave-health vulnerability. Clusters of high vulnerability were evident in Northern and Southern Australia during 2011-2016 but reduced in 2021. In greater cities, high clusters of vulnerability were apparent within Northern Adelaide and Western Melbourne for all the years. Among the heatwave types (low-intensity, severe, extreme), extreme heatwave days showed a positive association with heatwave-health vulnerability during all five consecutive years. The elderly people (65 years and over) and social isolation had a higher risk of heatwave-health vulnerability in 2011. For the remaining five consecutive years, the heatwave vulnerability was associated with low education, low income, high diabetes prevalence, and lower healthcare professionals across the suburbs. CONCLUSIONS: The findings suggest that future Australian heatwave mitigation strategies, such as heat health plans and adaptation programs, can be tailored to address these underlying drivers of heatwave vulnerability.