The major current and emerging risks to the built environment are shown in the assessment summary at the end of this section. The assessment of risks to the built environment examined here follows the method and concepts applied in SoE 2011. That is, risks examined here relate to incidents occurring at 1 point in time, rather than the impacts of pressures that may occur across longer periods. In analysing risk, the effectiveness of management responses and the resilience of the system are considered. As for SoE 2011, the assessments were made using qualitative analysis based on expert opinion.

Extreme weather and natural events are considered the largest risks to the built environment. The likelihood of occurrence of these events is considered ‘almost certain’, with the impacts variable, depending on the risk.

Despite the assessment that the built environment is quite resilient to extreme weather events (across the longer term), both mega-storms and mega-fires are considered catastrophic because of the immediate consequences of these events for property and infrastructure, loss of amenity, and human casualties. Pressures on the built environment from the cost and impacts of extreme mega-weather events will continue to increase. Population growth is also bringing pressure for settlement in places that are at greater risk from climate events.

For example, the Insurance Council of Australia declared 4 catastrophes—3 bushfires and 1 tornado—during the 2016 summer. The damage bill for 3 bushfires in South Australia, Victoria and Western Australia, and a tornado in New South Wales was more than $550 million. Overall, in the past couple of years, insurance losses from natural disasters has ramped up to well over $3–4 billion.

In addition, localised floods, storms, bushfires and heatwaves are all extreme weather risks that are considered ‘almost certain’ to affect the built environment, with consequences ranging from moderate to major.

Although extreme heat events have perhaps less devastating effects on physical infrastructure than bushfires, they do cause stresses and failures for energy infrastructure. Local services are also increasingly affected, such as local public libraries acting as refuges from the heat. These events are also becoming more prolonged, so their economic impacts are more pronounced. More people die during extreme heat events than in bushfires, but their impacts are broader than just on health. The expert group recommended that this risk continue to be assessed as ‘almost certain’, but be classified as major rather than moderate impact.

As a major contamination of the water supply is likely to be episodic, the expert group recommended that this risk remain in the ‘possible’ category. The risks of both contamination and interruption to the water supply have the potential to cause great damage, and are therefore considered major. It is also acknowledged that contamination of water supplies is occurring in some remote Indigenous communities at present.