Ä¢¹½´«Ã½

This study presents the first attribution assessment of the mortality burden of an Australian heatwave to climate change. It examines excess heatwave-related mortality, as defined by climatological criteria, in the state of Victoria during the 2009 Southeast Australian heatwave. An epidemiological model, derived from well-established methods that define the relationship between observed heatwave temperatures (95th, 97.5th, and 99th percentiles) and mortality, is applied to heatwaves in simulations that either include or exclude anthropogenic climate forcing from eight climate models.

Across all models, the frequency of a heatwave-related mortality event similar to the 2009 Victorian event has, on average, doubled under factual conditions compared to counterfactual conditions. Furthermore, an average of approximately 6 ± 3–4 additional deaths out of 31 (a 20% increase) is attributed to extreme temperatures resulting from anthropogenic climate influence. Despite the relatively small total number of attributable deaths according to the epidemiological model, six out of eight climate models predict a statistically significant anthropogenic influence, indicating that climate change increased the heatwave-related mortality impact of this event. In alignment with previous Australian-based studies, it is emphasized that focusing on mortality relative to the top 5% of temperatures logically results in a smaller mortality signal compared to the top 50% of temperatures, as would be identified using a broader temperature-related epidemiological model. As research, planning, and policy interest in the role of climate change in health burdens—and other adverse impacts of weather and climate extremes—continues to grow, fostering interdisciplinary collaborations remains essential to ensuring that the resulting science maintains high-quality rigor and policy relevance.