Outlook Australian environments have evolved within the context of, and sometimes in response to, extraordinary weather events that drive significant change in short periods of time. Tropical cyclones, hailstorms, flooding rains, storm tides, heatwaves, bushfires, blizzards and other natural phenomena are events that last hours or days, but can change landscapes, their productivity and the species that live in them for years or decades, and sometimes have irreversible impacts. Whenever these natural events intersect with people, and their livelihoods and infrastructure, they pose a hazard to life, property and regular functioning of our society and economy. When these events cause significant disruption, they are termed ‘natural disasters’. This is really a misnomer – although these hazards naturally occur, as a society, we have the capacity to alter our vulnerability to these events. Additionally, climate change caused by humans is affecting the scale, frequency and distribution of these events. Events often occur together or in close succession, magnifying or complicating their effects – for example, debris from treefalls may increase the risk of bushfires in following dry seasons. Coincident, consecutive and compounding impacts of natural processes may mean that the level of risk posed to environments, communities, infrastructure and industries is also complicated and increased, requiring more complex responses to reduce impacts or build resilience to them. Climate variability means that the effects of such short-term events may be magnified by the existing conditions. The summer of 2019–20 was notable for its bushfires, but these were especially fierce because the drought conditions that preceded them meant that the amount, availability and condition of bushfire fuels was also at an extreme level. Similarly, rainfall over weeks or months before a short-duration storm may cause more flooding because the ground is already saturated and the waterways are already full (as with the 2016 Tasmanian floods). Extreme events are defined by the Intergovernmental Panel on Climate Change as weather or climate variables that fall near the ends of the range of observed values (Seneviratne et al. 2012), whether they be at the upper end (such as very high wind speeds) or at the lower end (such as very cold temperatures). Climate change is likely to impose on us weather patterns and conditions that we have not experienced before and that fall outside the range of observed variables – we are beginning to experience ‘extreme extremes’ (see the Climate chapter). Climate change is thus predicted to exacerbate many of these events and their impacts. Tropical cyclones, particularly non-severe cyclones, are likely to become less frequent, so on average tropical cyclones may become more intense and deliver more extreme rainfall. Summer storms are likely to deliver their rainfall in shorter but more intense bursts, and high-fire-danger days are likely to become more frequent and more dangerous. The outlook for drought is that climate change will result in more frequent, more widespread, more severe and more prolonged droughts in some regions of Australia, with follow-on impacts for acute extreme weather events. Parts of northern Australia are projected to see a decrease in drought. The Climate Commission (Steffen et al. 2013) referred to the 2020s as the ‘Critical Decade’, during which strong preventive action is required to address the causes and consequences of climate change. From an economic perspective, Deloitte Access Economics suggests that 30% of employed Australians and more than 30% of national income is exposed to disruption from climate change and unplanned economic transition, with a loss of $3.4 trillion in gross domestic product and 880,000 jobs over the next 50 years if we do not act (Deloitte 2020). In contrast, they propose that growth to support a transition to net zero emissions of greenhouse gases by 2050 could grow the economy by 6% and jobs by 250,000 by 2070. The Royal Commission into National Natural Disaster Arrangements (Binskin et al. 2020) made recommendations about how to better prepare Australia for climate-related extreme events. The Australian Government broadly accepted all recommendations, and a series of policy proposals is addressing the integration and coordination of government responses. Inquiries into natural disasters by state and territory governments over the past few years are similarly driving policy responses. At the same time, industries, communities and nongovernment organisations are also starting to address the question of how to enhance community, business and environmental resilience. Impacts Increasing frequency, intensity and sometimes duration of extreme events will result in range of impacts on Australia’s environment, infrastructure, businesses and communities. Many communities are already experiencing these increases. Impacts on the environment Environmentally, many of Australia’s most valued and iconic ecosystems are at risk. The Great Barrier Reef is already facing unprecedented marine heatwaves, bleaching events and threats to coral recruitment. The Kakadu wetlands are at risk from saline intrusion due to sea level rise. Mangrove communities across northern Australia are dying from the effects of a combination of climate-driven factors, and bushfires have ravaged much of Australia in the past few years, burning into ecosystems that are typically resistant to fire. Impacts on human systems Buildings and infrastructure are at risk. Severe tropical cyclone Seroja crossed the Western Australian coast on 11 April 2021 as a category 3 cyclone, causing damage to 70% of buildings in Kalbarri and Northampton, and widespread power outages (BOM 2021e). This is unusually far south for a cyclone of this intensity, and thus the minimum building standards required for buildings and infrastructure were lower than for areas more usually exposed to such cyclones (Standards Australia 2002). Note that there were a few Seroja-type events in the first half of the 20th century, but none since 1956; detailed analysis of tropical cyclones started in the 1970s. Agriculture also faces significant effects, from the damage to tree crops caused by storms and cyclones to the effects of heat stress on domestic animals. More insidious impacts include disruption of the lifecycles of pollinators and beneficial predatory insects. Impacts on Indigenous culture and wellbeing Extreme and uncontrolled fire and flooding have resulted in damage to cultural sites, particularly in New South Wales and Victoria. This means that some traditional mapping points and boundaries between Countries that have been used by Indigenous Australians for millennia are gone, and that these cultural heritage sites and places that are also linked to storytelling are disappearing (Murawin 2021). Assessment Impacts of extreme events on wellbeing 2021 Adequate confidence The impacts of extreme events on the Australian environment are mixed: climate change and floods are having a negative impact, but other aspects are good or stable. However, the impacts of all extreme events are getting worse as they become more frequent and severe with climate change. Related to United Nations Sustainable Development Goal targets 1.5, 2.4, 11.5, 13.3 Legend How was this assessment made Share on Twitter Share on Facebook Share on Linkedin Share this link Assessment Climate change 2021 Adequate confidence Climate change is increasingly impacting human wellbeing, but currently we can engineer solutions and enhance community resilience to various aspects of climate change. We will increasingly need to see behavioural change rather than technical mitigation. Assessment Cyclones and storms 2021 Adequate confidence Better forecasting means that communities are typically aware of approaching storms in sufficient time to take appropriate action. Loss of life to cyclones has significantly decreased over the past century. Rapid response helps mitigate impacts. Increasing speed of intensification and unpredictable storm behaviour are likely to limit our capacity for planned response. Assessment Floods 2021 Adequate confidence Forecasting means that communities are, with notable exceptions, forewarned of potential flood and inundation events. Increasing frequency of heavy rain may increase unpredictability, limiting our capacity to respond in a timely manner. Assessment Heatwaves 2021 Adequate confidence We are typically able to engineer solutions to manage wellbeing impacts of short-term heatwaves, although marginalised individuals and communities remain at risk. Heatwaves are the single biggest climate-related cause of human mortality in Australia. Longer periods of high temperature are likely to exacerbate impacts. Assessment Bushfires 2021 Adequate confidence Technology to predict bushfire behaviour and enhance infrastructure resilience is improving. Community preference for living in bushland settings is increasing potential exposure. Climate change is likely to increase bushfire risk, but ongoing investment in improving protection of communities could mitigate some risks.