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Article | WTW Research Network Newsletter

A storyline approach for navigating complex and compound climate risks in Australia

By Jessica Boyd , Dr Ben Rabb and Anna Haworth | October 14, 2024

Climate change will increase natural catastrophe risk in Australia, further complicating the business risk landscape. Storylines can help businesses understand and manage these complex, compound hazards.
Climate|Environmental Risks|ESG and Sustainability|Property Risk and Insurance Solutions|Risk and Analytics|Willis Research Network
Climate Risk and Resilience

Australia faced numerous natural catastrophe events in the first half of 2024 (Figure 1):

  • January 25: Tropical Cyclone Kirrily, a Category 2 storm on the Australian Bureau of Meteorology (BoM) scale, struck Queensland, bringing strong winds and heavy rainfall.
  • February 14: Valentine's Day convective storms caused Victoria’s largest blackout on record, affecting 530,000 homes and businesses, resulting in over AU $100 million (US $67 million) in insured losses.
  • February 19: Convective storms hit New South Wales, causing injuries, transport disruptions and flash flooding in Sydney.
  • March 18: Tropical Cyclone Megan made landfallas a Category 3 storm (BoM scale) in the Northern Territory, bringing strong winds, heavy rainfall and flooding.
  • Early April: Widespread flash flooding in New South Wales led to AU $176 million (US $117 million) in insured losses.
  • Throughout early 2024: Bushfires affected both Perth and Victoria, leading to the evacuation of tens of thousands of people.
Map of Australia showing all natural catastrophe events in first half of 2024.
Figure 1: Notable natural catastrophe events in Australia in the first half of 2024

Source : WTW Research Network

While these events did not result in significant economic damage, they have highlighted the natural catastrophe risks that Australia faces, which are expected to escalate with climate change. The Intergovernmental Panel on Climate Change (IPCC) projects that climate change will increase the frequency and/or intensity of extreme weather events in Australia, [2] such as bushfires, floods and tropical cyclones, leading to heavier rainfall, stronger winds and longer wildfire seasons (Table 1). For example, events such as the flash flooding in April — historically mostly confined to coastal regions — are becoming more common farther inland as global warming is influencing the climate drivers that determine the frequency and location of extreme precipitation.[1]

Table 1. Projected climate change impacts to major atmospheric perils in Australia according to the IPCC
Table 1. Projected climate change impacts to major atmospheric perils in Australia according to the IPCC
Peril Direction of change Projected impacts
Bushfires Increase in bushfires Increase (Purple arrow pointing top right) Bushfires in Australia are projected to increase in frequency, severity and duration, particularly in southern and eastern Australia. This is primarily due to increasing mean temperature and cool season rainfall decline.
Tropical cyclones Decrease in number of tropical cyclones
Increase in the proportion of severe tropical cyclones
Decrease, (arrows pointing down) Increase (Purple arrow pointing top right) Fewer tropical cyclones are expected, but a greater proportion of them will be severe.
Severe convective storms Changes uncertain Question marks Future projections for lightning, hail, tornadoes and extreme wind gusts are uncertain. Long-term highquality observations are lacking, and climate models are unable to simulate these small-scale phenomena.
Flooding Increase in flash flooding
Increase in river flooding
Increase (Purple arrow pointing top right) More intense extreme rainfall events are expected, leading to increased flash flooding, especially in northern Australia. Smaller increases may occur in southern Australia, where drier antecedent conditions may lead to less surface runoff. Rainfall totals from east coast lows and tropical systems are expected to increase, leading to increased flood risk in the larger river catchments.

Storylines for climate risk management

Natural catastrophes such as these can disrupt critical infrastructure and business value chains in a variety of complex and interconnected ways. Using “storylines” — physically consistent narratives of plausible future events — helps us understand and manage these complex risks in a warming world. For instance, a storyline could depict a future where prolonged droughts lead to severe water shortages, increasing business costs and downtime — underscoring the need for effective water management strategies. These narratives are oriented around events that people can easily understand and relate to and allow us to clearly communicate which aspects we are more or less confident in (known as “partitioning uncertainty”).

WTW works closely with companies in the region to translate the latest climate and impact science into information that can be used to make business decisions. This includes the use of storylines that integrate climate model outputs, observational data and expert judgment to create extreme but plausible scenarios. These can guide new or upgraded risk management controls — usually in the context of a wider Enterprise Risk Management (ERM) framework.

A storyline approach is particularly useful for two types of risks:

  • Complex business risks with large uncertainties
  • Compound physical climate risks

Complex business risks with large uncertainties

Consider road freight worker health and safety, an important issue for many companies. In Australia, strong winds and bushfires have contributed to serious incidents in the past.[3] [4] A company might want to understand future climate impacts on worker or contractor safety to improve controls or business continuity plans. Conventional climate models — even locally downscaled — cannot provide these answers directly, but storylines, based on diverse information sources, can.

Key information sources for assessing bushfire risks in this context include:

  • Precedent events: Analyzing past incidents from Australia and other regions (e.g., fires in Maui, Hawaii, in 2023[5] or Chile in 2024) to understand their causes and impacts. What happened there and could it happen here?
  • Vulnerability and exposure: Examining how many vehicles use specific roads and at what times. Are certain types of vehicles more susceptible to risks?
  • Current and future hazard: Reviewing historical data on where fires have occurred in Australia and projecting how bushfire hazards may change over time in terms of severity, frequency and distribution. How might these changes affect road freight operations in the future?

An expert panel can then deliberate on this information in a structured manner.[6] Scores can be considered around the likelihood of a scenario occurring (noting that a likelihood score is not always needed in a storylines approach). Importantly, a confidence score can be given, which reflects the experts’ level of agreement, together with the amount and quality of the available evidence.[7]

Compound physical climate risks

Traditional risk assessments track individual threats by identifying historical trends in the magnitude and frequency of single hazards; however, this approach does not capture the risk from interconnected and cascading hazards, which have the potential to amplify risks for a company’s value chain. The resulting compound risks differ significantly from independent risks, often with distinct likelihoods and impacts.[8] [9]

The floods, tropical cyclones, convective storms and bushfires experienced in Australia during the first half of 2024 exemplify how hazards can strike in quick succession, creating transport delays, power cuts and critical supply shortages as well as affecting worker availability and safety.

A storyline approach views risks through the lens of the entire value chain, identifying interactions and compounding effects, which add up to something greater. Analyzing factors that could produce a significant shock event can inform shorter-term business continuity plans and longer-term strategic decisions such as mergers and acquisitions.

In the face of global change, there has never been a more important time to consider complex and compounding risks and their impact on a company’s short-term performance and long-term prosperity.

References

  1. Speer, M., Leslie, L., Hartigan, J. & MacNamara, S. Changes in frequency and location of East Coast low pressure systems affecting Southeast Australia. Climate 9(3), 44 (2021). Return to article
  2. IPCC. Climate Change 2021: The Physical Science Basis. (2021) Return to article
  3. The Sydney Morning Herald. Three men died in WA bushfire. (2007). Return to article
  4. The West Australian. Wind gust causes bus crash. (2009). Return to article
  5. WTW. Natural Catastrophe Review July – December 2023. (2023). Return to article
  6. Hemming, V., et al. A practical guide to structured expert elicitation using the IDEA protocol. Methods Ecol Evol.; 9: 169–180. (2018). Return to article
  7. Mastrandrea, M.D., et al. Guidance Note for Lead Authors of the IPCC Fifth Assessment Report on Consistent Treatment of Uncertainties. Intergovernmental Panel on Climate Change (IPCC). (2010). Return to article
  8. Network for Greening the Financial System. Compound Risks: Implications for Physical Climate Scenario Analysis. (2023). Return to article
  9. Arribas, A., et al. Climate risk assessment needs urgent improvement. Nat Commun 13, 4326. (2022). Return to article

Authors


Modelling Research & Innovation Lead
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Associate Director, Physical Risk, Climate Practice, WTW
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Associate Director, Research Climate Practice, WTW
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