Attribution of the health outcomes of heatwave to climate change

Heatwaves have adverse impacts on human health. These include increased ambulance callouts, exacerbation of underlying diseases, heat stroke, and in severe cases, death. The old, sick, or young are adversely affected by heatwaves, however fit and healthy people exposed to extreme heat over lengthy periods are also at risk.

Event attribution has demonstrated that the overwhelming majority of recently occurring heatwaves have a detectable anthropogenic signal behind their frequency and/or intensity. While the strength of the detected signal depends on the event in question and the underpinning methods, it is clear that heatwaves are more severe and occurring more often due to anthropogenic climate change.

A question being asked by climate scientists and health experts is whether health outcomes of heatwaves can be linked to climate change (Ebi et al. 2017).An example of how such assessments could be undertaken was performed on mortality rates during the 2003 European heatwave for London and Paris (Mitchell et al. 2016). However, the detail behind such approaches is often not clear to those outside of climate science or event attribution. Moreover, different approaches - from both climate and human health sides - may be required depending on the particular heatwave and health outcomes of interest.

Using case studies of Australian heatwaves, this talk will investigate what must be considered when designing attribution assessments on extreme events and impacts. We will discuss that while the framing of the attribution question is a fundamental step, constant liaising between the climate and human health communities is central. Moreover, we will discuss how the readily used fraction of attributable risk (FAR) methodology may not always be the most appropriate approach when determining how climate change has influenced the impacts of climate extremes.

Ebi, K.L., Ogden, N.H., Semenza, J.C. and Woodward, A., 2017. Detecting and attributing health burdens to climate change. Environmental health perspectives, 125(8), p.085004.

Mitchell, D., Heaviside, C., Vardoulakis, S., Huntingford, C., Masato, G., Guillod, B.P., Frumhoff, P., Bowery, A., Wallom, D. and Allen, M., 2016. Attributing human mortality during extreme heat waves to anthropogenic climate change. Environmental Research Letters, 11(7), p.074006.