Australians are not evenly distributed across the continent – access to resources, services, employment opportunities and lifestyle means that we are clustered in some of the areas most exposed to risk of weather- and climate-driven extreme events: coasts, floodplains and open woodland systems on hillsides. Populations are increasing in exposed regions as the peri-urban population expands, and development continues on floodplains and coastlines. At the same time, for some weather types, the hazard-exposed regions are expanding towards some of Australia’s biggest population centres. For example, tropical cyclone risk is increasing in south-east Queensland, northern New South Wales and south-west Western Australia as sea surface temperatures increase (Buckley et al. 2019). The consequence is that a greater number of people are exposed to risks from extreme weather events, or the consequences of climate change as mediated through environmental change. The most impacted by the effects of extreme events will, in general, be the most vulnerable members of society. Extension of the risk of impacts from extreme events into poorer parts of large cities will significantly increase the number of individuals potentially seriously affected, with consequent pressures on planning and recovery operations. Urban expansion Population size is increasing in many at-risk landscapes, including in some areas on coastal floodplains and coastlines that are prone to erosion. Analyses of data from the Australian Bureau of Statistics suggest that about 85% of Australia’s population lives within 50 kilometres of the coast. The number of people living within 50 kilometres of the coast has increased during the past 10 years by 16%, against a national population increase of 15%. We have also seen increases in some areas in the number of people residing in peri-urban and rural bushland environments. In Victoria, the settlements most heavily affected by the Ash Wednesday (1983) and Black Saturday (2009) bushfires have retained their populations or increased in size in subsequent decades (McKenzie & Canterford 2018). This places more people in high-risk contexts, which may be exacerbated when the population demographics change – for example, to a more aged community. Legacy construction and planning Building codes have historically prioritised occupant health and safety over damage to property and resilience. Standards Australia is working with the building and construction industries, all levels of government, and researchers to update standards to ensure that new building work can resist probable weather extremes (see the Urban chapter). As the magnitude, direction, frequency and duration of these extremes change, there is a potential shortfall in the engineered capacity of a building or other structure to resist. Older structures may pose more of a liability if they were built before recent updates to standards. Both the Royal Commission into National Natural Disaster Arrangements (Binskin et al. 2020, chapter 19) and the final report of the Northern Australia Insurance Inquiry by the Australian Competition and Consumer Commission (ACCC 2020, chapter 13) noted that legacy issues in land-use planning and building contribute to increased risk for affected properties and communities. The report made recommendations to address these issues by improving land-use planning and building standards for future development. In addition to the standards to which buildings were built, there is also increasing evidence that maintenance to retain compliance standards is not routinely monitored, which leaves some communities and industries at greater risk than may be apparent (Department of Fire and Emergency Services, Western Australia, pers. comm.). Assessment Frequency and severity of extreme events 2021 Adequate confidence Bushfires and heatwaves are increasing in frequency and intensity. Although floods and storms are currently stable, it is expected that all extreme events are increasing with climate change. Related to United Nations Sustainable Development Goal target 13.1 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 apparent now in global, national and regional data. Modelling tells us that climate systems inertia will mean that change will increase for decades even if we do address the drivers of change. Assessment Cyclones and storms 2021 Adequate confidence Periods of increasing and decreasing storm activity are apparent in long-term historical and environmental records. Modelling suggests that storms and cyclones will become more intense, but not necessarily more frequent. Different models give different predictions for the extent to which tropical cyclones will track further south than they have tended to in the historical record. Assessment Floods 2021 Adequate confidence Modelling and recent experience suggest that rainfall will become more intense, even if total rainfall decreases or the dry periods between events increase. This is likely to increase the frequency of flood events and their unpredictability. Assessment Heatwaves 2021 Adequate confidence The intensity and duration of heatwave events are already exceeding historical records. Modelling suggests that this will get worse. Assessment Bushfires 2021 Adequate confidence Bushfires are a natural occurrence, but we have recorded unprecedented events recently. Modelling suggests that dangerous bushfire weather is likely to become more frequent, and the antecedent conditions for high-intensity bushfires are likely to become more common.