Attention is now focused on the frequency and intensity of extreme weather events. Hub researchers Dr Savin Chand and Dr Hamish Ramsay explore the debate on what the data says about tropical cyclones.
We often hear general statements that climate change will increase the frequency and intensity of extreme weather events, but for tropical cyclones, the story is more complex.
Data shows that the number of tropical cyclones occurring globally every year has decreased by approximately 13 per cent from 1900 to 2000 compared with the period between 1850 and 1900. Our study published in Nature Climate Change reveals that Australia has experienced an even greater decline since the 1950s, when global warming began to accelerate.
But in robust scientific tradition, not all agree and trends in the frequency of tropical cyclones are currently being debated within the scientific community.
Professor Kerry Emanuel from Massachusetts Institute of Technology argues in Matters Arising in Nature Climate Change, (Emanuel 2023) that the century-scale historical climate datasets we have considered are inadequate for assessing long-term trends in cyclone numbers. In reply, we contend Chand et al., (2023) that Emanuel’s methodology is not suitable for determining tropical cyclone trends, as it detects too many circulations that are too weak, too small, too dry and/or too short-lived to be tropical cyclones. This highlights the need for ongoing research and testing of approaches to give us confidence in the projections so we can better understand the risk of tropical cyclones in the future.
What is clear is that, despite a likely decrease in the number of tropical cyclones due to global warming, especially in the Southern Hemisphere, the risk posed by individual tropical cyclones is expected to increase in the future due to higher sea levels, increased rainfall intensity and higher peak wind speeds, on average.
Effective climate change adaptation requires a better understanding of the future impacts of tropical cyclones at regional and local scales. Key questions we are trying to answer include:
- Will we have more tropical cyclones making landfall?
- Will landfalling tropical cyclones bring more intense rainfall and stronger winds, increasing the risk of flash flooding and damage?
- Will tropical cyclones move further south, increasing the risk to places like South-East Queensland, Northern New South Wales and South-West Western Australia?
Hub researchers, from the project Regional climate change guidance for local action, are working with stakeholders to try and answer these questions. To stay updated or find out how you can be involved, subscribe to our hub newsletter.
Dr Savin S. Chand is a Senior Lecturer in Applied Mathematics and Statistics at the Institute of Innovation, Science and Sustainability, Federation University
Dr Hamish Ramsay is Team Leader of Extreme Weather and Climate Processes, CSIRO