Heatwave defined as a heat impact event for all community and emergency sectors in Australia

This is a paper presented at the 2013 Bushfire CRC Research Forum.

Lack of agreement over a heatwave definition has impeded spatial and temporal analysis of events within Australia and with comparable locations internationally. Given that heatwaves impact all natural and human engineered systems in a similar manner it seems logical to derive a measure that permits this form of analysis so that heatwave mitigation best practices may be shared. As Australia is yet to develop a national heatwave warning system, features that have shaped heatwave warning systems in Europe and the USA are examined to inform how a domestic system may evolve. A heatwave definition that can serve an Australian heatwave warning system has been created through considering how systems respond under heat load. Systems susceptible to failure under thermal stress have natural or engineered design limitations. These limits are an adaptive response to commonly experienced rates of heat accumulation found over both the long (climate scale) and short (acclimatisation) term. When these limits are exceeded, systems begin to fail. The larger the thermal load, the greater is the impact and scale of failure. Short and long term heat anomalies are factored together to derive a measure of heatwave intensity. This heatwave intensity measure has been shown to be useful for charting Australia's heatwave climate history, forecasts, warnings and assessment of risk arising from climate change. A statistical interpretation of the climatology of heatwave intensity has then been developed to provide guidance on heatwave severity in chart form providing guidance on the level of impact anticipated due to the intensity of the heatwave (Nairn and Fawcett, 2013).