EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Attribution of excess heat-related death toll during 2009 heat wave in Victoria, Australia

Philipp Aglas-Leitner1,2,3, Sarah Perkins-Kirkpatrick3, Nina Lansbury4, Linda Selvey4, Nicholas Osborne5,6,7, and Daithi Stone8
Philipp Aglas-Leitner et al.
  • 1Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria (
  • 2Climate Change Research Center, UNSW, Sydney, Australia
  • 3School of Science, UNSW Canberra, Canberra, Australia
  • 4School of Public Health, University of Queensland, Brisbane, Australia
  • 5School of Public Health, Faculty of Medicine, University of Queensland, Brisbane, Australia
  • 6School of Population Health, University of New South Wales, Sydney, Australia
  • 7European Centre for Environment and Human Health (ECEHH), University of Exeter Medical School, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall, United Kingdom
  • 8NIWA, Wellington, Aotearoa, New Zealand

In recent decades, anthropogenic climate change has led to significant increases in heat wave length and intensity. Many of these heat waves have resulted in substantial impacts on human health. In 2009, the state of Victoria, Australia, experienced several days with maximum temperatures rising 12-15°C above the climatological mean and a marked rise in the human death toll. This study attempts to directly quantify the heat-related human fatalities of the 2009 heatwave attributable to anthropogenic climate change.

We focus on changes in return values of heat wave-related mortality. Furthermore, we combine two types of modeling tools. The first is a set of large initial-condition ensembles of simulations from atmosphere-only models from the weather@home/ANZ and C202C+ D&A projects, and large initial-condition ensembles of simulations from atmosphere-ocean models from CMIP6.  We compare factual outcomes from year-2009 era periods from historical simulations against counterfactual outcomes from either naturalised (non-anthropogenic) simulations or pre-industrial times. The second tool is an empirical model linking heat-related mortality to exceedance of temperature percentile thresholds from daily climate simulation output. This mortality model categorizes heat waves based on three consecutive percentile windows starting at the 95th, 97.5th, and the 99th percentile.

Our analysis shows considerable agreement among the climate-mortality model combinations indicating significant increases in human fatalities during conditions comparable to the 2009 Victoria heat wave under anthropogenic climate change. Most models attribute approximately one third to one half of excess heat-related deaths to anthropogenic greenhouse gas emissions. These findings demonstrate that unless significant climate change mitigation and adaptation efforts are undertaken, further increases in heat-related mortality risk can be expected.

How to cite: Aglas-Leitner, P., Perkins-Kirkpatrick, S., Lansbury, N., Selvey, L., Osborne, N., and Stone, D.: Attribution of excess heat-related death toll during 2009 heat wave in Victoria, Australia, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-6412,, 2023.