A long-term view of tropical cyclone risk in Australia

Abstract

Natural hazard risk is assessed by leveraging, among other things, the historical record. However, if the record is short then there is the danger that risk models are not capturing the true envelope of natural variability. In the case of tropical cyclones in Australia, the most reliable observational record spans less than 50 years. Here, we use a much longer (ca. 6000-year) chronology of intense paleo-cyclones and, for the first time, blend this information with a catastrophe loss model to reassess tropical cyclone wind risk in Northeast Australia. Results suggests that the past several decades have been abnormally quiescent compared to the long-term mean (albeit with significant temporal variability). Category 5 cyclones made landfall within a section of the northeast coast of Australia almost five times more frequently, on average, over the late Holocene period than at present. If the physical environment were to revert to the long-term mean state, our modelling suggests that under the present-day exposure setting, insured losses in the area would rise by over 200%. While there remain limitations in incorporating paleoclimate data into a present-day view of risk, the value of paleoclimate data lies in contextualizing the present-day risk environment, rather than complementing it, and supporting worst-case disaster planning.

Investigation of the Development of Tropical Storm Nicholas based on Global and Regional Climate Data

“…The geographical static data provided by Mesoscale and Microscale Meteorology (MMM) Laboratory, the National Centre for Atmospheric Research (NCAR) was employed for the WRF simulation, consisting of topography, land use and soil type (Mortlock et al, 2023;Wang et al, 2019).…”

“…Moreover, Cyclone Nicholas, which occurred in Western Australia, also generated high wave phenomena and sea level anomalies on the western coast of Sumatra and the southern coast of Java and Bali (Anushka et al, 2018). The cyclone struck suddenly and posed a significant hazard as it fell on the mainland (Mortlock et al, 2023;Xi, et al 2023). According to the summary issued by the Australian government, Cyclone Nicholas was a severe typhoon with the wind speed increasing by around 10 to 13 km/h (Aragon et al, 2016).…”