Landscapes and seascapes

Australia has diverse landscapes and seascapes, from our desert interior to our farming lands, beaches, coral and temperate reefs, open oceans, wetlands and rainforests. This state of the environment report assesses these various aspects of our environment, along with the ecosystems and biodiversity they support.

Assessment Landscapes and seascapes

2021

Assessments of state range from very poor to very good
Assessments of trend range from deteriorating to stable

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Assessment Land and soil

2021

Soil and land condition is generally poor as a result of high overall loss of soil organic carbon. The trend in condition is deteriorating as a result of land clearing, unsustainable agricultural practices and erosion, and climate change, although there are some recent improvements in soil under forests.
Assessments of state range from poor to good
Assessments of trend are deteriorating
Related to United Nations Sustainable Development Goal targets 2.4, 12.4, 13.2, 15.3

Assessment Inland water

2021

Low levels of rainfall in southern Australia, combined with demand for town water and irrigation, have reduced both groundwater and surface water levels, particularly in the south-east. Similarly, in northern Australia, water resources were reduced by the late onset of the monsoon seasons in 2017–19, with associated poor rainfall during the wet season over consecutive years.
Assessments of state are poor
Assessments of trend are deteriorating
Related to United Nations Sustainable Development Goal targets 6.1, 6.5, 6.6

Assessment Coasts

2021

Waterways, beaches and shorelines are generally in poor condition in areas near urban centres, due to coastal development and climate change, but in good condition in more remote areas. Rocky shorelines, mudflats and sandbars are vulnerable to ongoing pressures.
Assessments of state range from poor to good
Assessments of trend range from deteriorating to stable
Related to United Nations Sustainable Development Goal target 14.2

Assessment Marine

2021

The marine environment is predominantly in good condition overall, but nearshore reefs are in poor condition and deteriorating as a result of the effects of climate change and cumulative pressures. Also, many habitats and communities that are in good condition overall are highly impacted in some locations. Climate change continues to warm and acidify the ocean, and we have experienced several major marine heatwaves over the past 5 years, resulting in an overall deteriorating trend.
Assessments of state range from very poor to good
Assessments of trend range from deteriorating to improving
Related to United Nations Sustainable Development Goal targets 14.1, 14.2, 14.4, 14.5

Assessment Air

2021

Air quality in Australian cities is generally within national standards, although particulate matter and ozone are increasing in several capital cities. Measurements are taken only at a limited number of places. There were substantial impacts from bushfires in 2019–20.
Assessments of state range from good to very good
Assessments of trend range from deteriorating to stable
Related to United Nations Sustainable Development Goal targets 3.9, 11.6, 12.4

Assessment Urban

2021

Australia’s urban environments are in good, livable condition; however, housing affordability and accessibility of services are an issue in some areas. Livability is lower in smaller urban communities than in larger cities. Continuing urban growth, climate change and waste processing are ongoing challenges.
Assessments of state are good
Assessments of trend are stable
Related to United Nations Sustainable Development Goal targets 9.4, 11.1, 11.2, 11.3

Assessment Antarctica

2021

Although the state of Antarctica is generally good, signals of change and variability are continuing to emerge. Most significantly, the ice sheet is providing an increasing contribution to global sea level rise; sea ice is showing large regional variability; and changes are occurring in the acidity, salinity and temperature of the Southern Ocean.
Assessments of state range from poor to good
Assessments of trend range from deteriorating to unclear
Related to United Nations Sustainable Development Goal targets 11.4, 12.4, 12.5, 13.2, 14.2, 14.a, 14.c

Land

Australia’s land cover is constantly changing in response to both natural processes and human activities. Land use in Australia continues to intensify. Almost half of Australia is used for grazing. The land areas committed to forestry, irrigated cropping and dryland cropping have increased.

Many parts of Australia are becoming highly degraded, and all remaining native vegetation has been modified to some extent. For example, in 2013, averaged across New South Wales the capacity for habitat to support native species and ecosystem was only 33% of the original capacity. In 2018, the New South Wales Government reported that only 15% of remnant native vegetation was in near-natural condition. Following the millennium drought (2000–10), periods of drought in the past 5 years have further degraded the condition of the land, particularly in the Murray–Darling Basin (see Terrestrial ecosystems and native vegetation). In addition, in the summer of 2019–20, bushfires burned more than 8 million hectares of native vegetation across 11 terrestrial bioregions, and 17 major vegetation types were severely burned. In an analysis of the current state and recent trajectories of 19 ecosystems, spanning Australia’s lands, seas and terrestrial Antarctica territory, 10 of the 18 ecosystems at risk of collapse are terrestrial (Bergstrom et al. 2021).

Soils underpin the productivity of the land. They were formed over very long time periods from the weathering of rocks, transport of sediments and interactions with living organisms. A decline in the amount and health of soil directly affects its ability to provide important ecosystem services that support our natural environment and agricultural industries. The ecosystem services that soils deliver are valued at an estimated $930 billion per year, making soils Australia’s most valuable natural asset (Soil Science Australia 2019).

Soil stores 3 times more carbon than either the atmosphere or terrestrial vegetation, and depleted soils can potentially contribute to reductions in atmospheric carbon (see Greenhouse gas emissions). Higher levels of organic carbon in soil increase land productivity through enhanced fertility and water-holding capacity. As a result of changed land use over the past 2 centuries, Australia has the third highest amount of soil organic carbon loss in the world, behind China and the United States (Sanderman et al. 2017). Ongoing clearing and unsustainable agricultural practices continue to impact the health of soils in Australia; however, in recent years, slight increases in below-ground carbon stocks have been detected where land use is stable under forests (DISER 2021h).

Between 2010 and 2019, the net carbon budget associated with land-use change in Australia reversed so that land-use change became a ‘sink’, with 15 million tonnes of carbon dioxide (CO₂) sequestered per year on average (Canadell 2021). Overall, net ecosystem productivity (above and below ground) sequestered 746 million tonnes of CO₂ per year over the same period. However, the extensive 2019–20 bushfires across eastern Australia caused major losses, releasing 670–830 million tonnes of CO₂ to the atmosphere. Moreover, the sinks from the land sector are still not enough to balance Australia’s carbon budget with industry sources, resulting in a net release of 23 million tonnes of CO₂ to the atmosphere on average each year over that decade (Canadell 2021).

Inland water

Water availability and quality are vital to the wellbeing of Australia’s people, ecosystems and economy. Our freshwater resources and river flows are driven by highly variable rainfall and climate. Since 2016, Australia has experienced both years of higher-than-average rainfall and the driest 24-month period on record. The state and trends of surface waters, groundwater, water quality, ecological processes and species populations deteriorated across many parts of the country, largely due to the extreme climatic conditions and ongoing pressures from water resource development, land use, salinity, bushfire and introduced pests. Northern freshwater systems have generally been subject to fewer pressures and are in a much better state than those in the south.

Rainfall and streamflow

In many parts of Australia, our highly variable rainfall has a significant impact on the availability of water resources (Gill 2011). Australia’s streamflow is the third most variable in the world, and its variability is double that of most other countries. Australia has a mean annual rainfall of 457 millimetres (1900–2020). The mean rainfall for 2016–17 was 580 millimetres; this was the tenth wettest year on record measured across the whole of Australia, although the east coast and much of the south-west were drier (BOM 2018). The calendar year 2019 was Australia’s driest on record, with 276 millimetres of rainfall, and the 24 months from July 2018 to June 2020 were also the driest on record (BOM 2020a). Drought conditions across south-eastern Australia intensified in 2018–19, particularly in the northern parts of the Murray–Darling Basin. North-western Australia was also dry, with a delayed monsoon onset contributing to a below-average wet season (BOM 2020b).

Northern Queensland was an exception in 2018–19, with higher-than-average flows and annual streamflows in several rivers the highest on record. Heavy rainfall in early 2019 produced extensive flooding in Townsville, major flooding in the Burdekin River and high flows into Kati Thanda–Lake Eyre, which resulted in an explosion of biodiversity, including a significant increase in waterbird abundance in the Lake Eyre Basin (BOM 2019).

Dry conditions during the latter half of 2019 contributed to generally below-average streamflow across the whole country. Low rainfall, streamflows and storage levels resulted in pressure on water-dependent ecosystems (see Freshwater ecosystems) and industries, with low allocations to water licence holders. Recovery commenced in 2020, with flows occurring in all the major rivers within the Murray–Darling Basin. Flow in the lower Darling River reconnected with the Murray River in mid-April 2020 for the first time since January 2018. In February 2020, the first major flows in 8 years occurred from the lower Balonne River into the Ramsar-listed Narran Lakes wetland system (see Wetlands) (BOM 2021a).

Water storage and use

In Australia, only 9% of rainfall becomes run-off, on average, and approximately 2% percolates through the soil to recharge groundwater. The rest evaporates back into the atmosphere, mainly through vegetation (Davis 2007). The level of run-off produced by rainfall depends not only on rainfall levels, but also on temperature and catchment condition. Run-off levels may take a considerable time to recover after drought conditions improve.

Australia’s high variation in rainfall and streamflow, and high temperatures, have meant that large reservoirs have been built to ensure reliable supply (McMahon et al. 2007a, McMahon et al. 2007b, McMahon et al. 2007c). Australia has more than 500 major surface-water storages, several thousand small storages and more than 2 million farm dams.

After reaching full capacity in April 2011 following the end of the millennium drought, the accessible storage volume of water across Australia has varied but has generally been well below full capacity due to lower-than-average rainfall across much of the country (see Figure 1).

Groundwater

Groundwater supports a range of different ecosystems, including wetlands and rivers (see Wetlands), terrestrial ecosystems relying on subsurface groundwater (see Terrestrial ecosystems and native vegetation), and cave and aquifer ecosystems (see Groundwater species).

Groundwater also supplies a significant amount of water for human use, although less than surface water. In many regions, groundwater is the only reliable water source for agriculture, mining and urban use. Groundwater for urban water supply is particularly important for Western Australia, where the Gnangara groundwater system is Perth’s lowest-cost and largest source of good-quality water (DWER 2021).

Drought conditions and the resulting decrease in surface water availability increased dependency on groundwater across much of the country over the past 5 years; on average, groundwater comprised 20% of water supply in 2019–20 compared with 14% in 2016–17. Groundwater responds more slowly to climatic conditions, and many aquifers have not yet returned to pre–millennium drought levels. The lower-than-average groundwater levels experienced in 2018–19 in many parts of Australia persisted in 2019–20 for all aquifer groups. The majority of bores in the middle and lower aquifers, where most extraction occurs, had below-average groundwater levels (56% and 54%, respectively), with generally stable or declining 5-yearly trends (BOM 2021a).

The Murray–Darling Basin and south-eastern Queensland have low groundwater levels because there has been limited aquifer recharge due to the low rainfall experienced across the region over the previous 3 years, coupled with an increase in the volume of allocated groundwater taken. When rainfall conditions and surface water availability started to improve in early 2020, groundwater extraction decreased. But despite the rainfall and reduced extraction, groundwater levels did not recover completely.

Similarly, bores in the Darwin and Daly–Roper water control districts in the Northern Territory had declining trends across 2015–20 because the normal increase in groundwater levels during the wet season did not occur as a result of 2 poor wet-season rainfalls (BOM 2021a). Aquifer discharge into parts of the Daly River system provides dry-season flow, which makes it one of the few perennial river systems in northern Australia with consequently high cultural and environmental values (BOM 2021c).

In south-west Western Australia, groundwater levels have generally been declining for the past 40 years as a result of decreasing rainfall (BOM 2018) coupled with increasing groundwater demand. Measures to reduce and redistribute groundwater extraction have been undertaken to slow the rate of decline in groundwater levels, and groundwater trends in the previous 5 years have been mostly stable.

Salinity

In many parts of Australia, soils, surface water and groundwater have a high salt content due to the dry climate and highly weathered landscape. Many Western Australian streams are naturally more saline than streams in northern Australia and along the eastern divide, where greater rainfall dilutes salt concentrations (BOM 2021a). Clearing of deep-rooted native vegetation for irrigated or dryland crops and pastures has changed water balances in many catchments, mobilising highly soluble salts that rise to the surface and eventually discharge into waterways. In 2019–20, 61% of Australia’s river and stream sites were on average fresh and suitable for drinking, 13% were marginal, and the remaining 26% were brackish or saline. For the previous year, 73% sites were fresh, 9% were marginal, and the remaining 18% were brackish or saline (BOM 2021a).

Dryland salinity adversely impacts agriculture and available water resources, as well as biodiversity, particularly in wetland areas in many parts of southern Australia. South-western Australia is particularly affected. A review found that government agencies have focused on protecting individual, high-value assets, and have not met wider legislated responsibilities to prevent and mitigate land degradation, and protect water resources and biodiversity throughout the south-west (OAGWA 2018).

Environmental water

In all states and territories, areas of intensive water use are subject to water planning processes to manage levels of extraction and to safeguard water to sustain the environment. Water for the environment is provided through rules-based ‘planned’ water (allocation limits and access rules) or, much less commonly, ‘held’ environmental water entitlements.

Overallocation of water resources and environmental degradation have been particularly pronounced in the Murray–Darling Basin, driving the 2012 Basin Plan initiative to rebalance environmental and consumptive use, and recover water for the environment (see Murray–Darling Basin). The allocation of water to all entitlement holders in the Murray–Darling Basin was low in 2018–19 and 2019–20, and this included allocations to held environmental water entitlements. A review of 3 major fish deaths in the lower Darling River in 2018–19, by the Australian Academy of Science, found that ‘the root cause of the fish kills is that there is not enough water in the Darling system to avoid catastrophic decline of condition through dry periods’ (AAS 2019).

Nonetheless, assessments have found that environmental watering has started to achieve local benefits. Without it, ecosystem decline over the recent drought period would have been even more severe (Productivity Commission 2021a).

Environmental water also provides other cultural, social and economic benefits. In particular, the delivery of watering events is increasingly integrating Indigenous knowledge to improve environmental outcomes, and achieve distinct cultural and spiritual outcomes. However, existing laws for water management are inadequate to achieve these outcomes. Indigenous people call for greater recognition of Indigenous water rights, and to enable Traditional Owners to give effect to their laws and customs for management of water on Country. This includes increasing use of existing water rights (O’Donnell et al. 2021). The National Cultural Flows Research Project identified 3 levels of Traditional Owner participation needed for cultural water: water rights, more influence in water landscapes, and transforming foundations (see Indigenous management).

Coasts

The productive shallow waters and fertile soils of Australia’s much-loved 33,000 kilometres of coastline give rise to a huge number of species and a proliferation of life. However, with some 87% of Australians living within 50 kilometres of the shoreline, the diverse pressures on coastal environments are intense. As the pressures of climate change have accelerated over the past 5 years, human populations have simultaneously increased, and industry and urbanisation have expanded into new areas, leading to reductions in available natural habitat, and degradation of some ecosystems.

Overall, Australia’s coastal land and waters are in poor condition. Of 19 major stressors on our coasts assessed in this report, only 2 (nutrient pollution and aquatic invasive species) have improved since 2016; 10 have deteriorated, and 7 are stable. This highlights the inadequacy of conservation and restoration efforts over the period. At the same time, the balance of climate versus population and industry-driven pressures has shifted. Extreme climatic events, including heatwaves, droughts, bushfires and floods, have become the increasingly dominant pressure, dwarfing some of the population-driven impacts, and making coastal protection and restoration more complex and challenging.

Recent bushfires caused staggering losses to coastal biodiversity and the ecosystem services on which human wellbeing depends (see Bushfires). The high loads of sediment and ash that flowed into waterways when above-average rains followed the 2019–20 bushfires exacerbated the impacts on burnt catchments. Substantial deaths were recorded for 11 species that live only in coastal estuaries; this is the first global record of bushfire impacts on water quality extending into estuaries (Silva et al. 2020). Bushfire run-off into estuaries and bays is likely to have also led to reduced oxygen levels and algal blooms, affecting the diverse, abundant invertebrates that play a critical role in local ecosystems (Joehnk et al. 2020) (see Marine and coastal ecosystems).

Overall, water quality in coastal regions is good, but conditions are variable, and multiple pressures persist. Although improved land management practices have somewhat reduced the levels of pollutants in the waters of the Great Barrier Reef, the overall estuarine condition remained poor in the 2019 Reef report card (DES 2021). Harmful algal blooms generally have a low impact across Australia; however, in southern Australia, river flows have declined significantly in the past 15 years following extended drought, so water quality has declined in the riverine portions of estuaries, causing periodic algal blooms and occasional fish deaths. By contrast, New South Wales statewide monitoring found that 75% of estuaries had low algal abundance between 2017 and 2019, up from 57%, indicating potential improvement. But the monitoring also found that the temperature and acidity of estuaries were increasing in response to climate change at a much faster rate than ocean modelling predicts (Scanes et al. 2020).

Coastal areas

Australia’s thousands of ocean beaches, loved for their exceptional aesthetic value and opportunities for recreation, are generally in good condition. Dune vegetation, however, has continued to decline nationwide, and beaches in coastal estuaries and bays, also valuable natural assets for recreation, are in poor condition and deteriorating.

The rocky shorelines that provide habitat for a highly diverse mix of species adapted to harsh conditions often support assemblages (collections of species) found only in the local region. Climate change–driven increases in air and sea temperatures stress many species such as rock oysters, and heatwaves can lead to large numbers of deaths, even in remote, pristine locations (Starko et al. 2019). As climate change pressures coincide with reduced water quality and continued urbanisation, rocky shorelines have deteriorated since 2016 and are in a poor state. Intertidal mudflats and sandbars support diverse communities of invertebrates, an important prey resource for fish and large, mobile invertebrates at high tide, and shorebirds at low tide. These habitats are currently in good condition but are also deteriorating.

Australia’s coastal waterways are the arteries of coasts, transporting food, nutrients and waste, and providing key habitat for aquatic species. These highly valued, productive and relatively sheltered places include a diverse range of wave- and tide-dominated estuaries, wetlands, bays, coastal lakes and lagoons, tidal creeks, deltas and stranded plains (Heap et al. 2001), all with unique traits. Their values also mean that they are exposed to numerous human pressures, including urbanisation, recreation, industry and trade (Hallett et al. 2016).

The environments of estuaries, and their wetlands and coastal bays include seagrasses, mangroves, shellfish reefs and rocky reefs, and a variety of sediment types. This diversity of habitat, and the variable estuarine environment where fresh river water meets the sea, mean that these systems support a unique and abundant mix of species.

Although the condition of these environments depends largely on their proximity to population centres, agriculture and industry, events since 2016 have highlighted the increasing threats of climate change and extreme conditions. The condition of estuaries, bays, and coastal lakes and lagoons is poor overall, despite many initiatives to remediate and restore catchments, and variations between locations. The poor condition of coastal waterways has stressed many important habitats (see Marine and coastal ecosystems).

This has negative consequences for human society. For coastal Indigenous people, the waterways that run through sea Country underpin all aspects of their living cultures and communities, and their connections to each other, to ancestors and to Country. Waterways are also a focal point for many cultural activities, including leisure and food (Stronach et al. 2019). Connections to these waterways are observed through many artworks, stories, dances and ceremonies.

Islands

Australia contains numerous diverse kinds of islands, such as equatorial tropical atolls (e.g. Cocos–Keeling); coral cays; tropical, subtropical and temperate continental islands; sea stacks; the world’s largest sand island (K’gari–Fraser Island); seamounts forming oceanic islands (e.g. Lord Howe and Norfolk islands); and subantarctic islands (e.g. Heard and Macquarie islands). Many of these islands provide ecosystem services that underpin the lifestyle, economic development and cultural practice for those who live there or have a connection with them. For Traditional Owners of islands, their entire Country, sense of connection and identity are attached to the health of their island home. Many islands are essential locations for a staggering amount of Australia’s biological diversity; islands support more than 35% of threatened species listed under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).

The overall state and trend of Australian islands are difficult to determine because we lack adequate ecosystem inventory information, and they are typically overlooked. Where information is available, the condition of islands varies enormously – from highly altered (e.g. some residential islands in south-east Queensland and north-eastern Australia) to largely unmodified (e.g. the Kimberley islands in north-western Australia) to almost pristine (e.g. subantarctic Heard Island). All are threatened by invasive non-native species and the effects of climate change, and many are threatened by overexploitation by people and industries. Larger islands are more resilient, but some have been badly affected by extreme events, such as the 2019–20 bushfires that devastated Kangaroo Island, South Australia.

Marine

As an island nation, Australia’s 13.86 million square kilometres of marine waters – including significant areas of 3 of the world’s 4 major oceans – are deeply connected to our modern national identity, and integral to our economy and way of life. Marine waters hold deep meaning for the Traditional Owners of sea Country. Since the 2016 state of the environment report, the major threat to the health and resilience of Australia’s marine environment has been climate change and associated weather extremes. Climate change is responsible for warming water temperatures, increasing acidification and salinity, changes in ocean circulation, and declines in the availability of nutrients and dissolved oxygen, all of which negatively impact vulnerable habitats and ecosystems (see Marine and coastal ecosystems).

The key processes that underpin the state of marine ecosystems are generally in good condition. Australia’s oceans are among the clearest in the world (Doblin et al. 2021), enabling relatively deep light penetration. This facilitates photosynthesis in microalgae or phytoplankton, which are the primary producers that form the foundation of the marine food web. Increases in the biomass of both phytoplankton (van Ruth & Matear 2021) and zooplankton have been reported since 2016 (Richardson et al. 2021b). However, changes in ocean currents and the distribution of habitats, communities and species in response to climate change – as well as other major disturbances such as historical declines in large predators, and the historical or current exploitation of various commercially valuable fish and other species – are disrupting the connectivity of ecosystems and the structure of food webs (Condie et al. 2021).

Demand for food, energy and other resources from the marine environment is growing, resulting in the rapid development of our blue economy, which is increasing at 2–3 times the rate of the rest of Australia’s gross domestic product (AIMS 2021). Consequently, Australia’s seascapes are becoming increasingly crowded and noisy. These changes, in combination with pollution (e.g. plastics, marine debris, petrochemicals, excess nutrients, sediments, pesticides) are challenging the management of marine ecosystems and the protection of the many ecosystem services they provide (Costanza et al. 2014, Beaumont et al. 2019, Smale et al. 2019).

However, the sustainability of the commercial harvesting of Australia’s diverse wild-caught marine fisheries has improved over the past 5 years, with 86% of stock assessed in 2020 classified as not overfished. These fisheries catch scallops, prawns, crabs, squid, rock lobster, abalone, coastal fish such as whiting and flathead, reef fish such as coral trout, shelf and deepwater fish such as ling and blue-eye trevally, and oceanic tuna and billfish, contributing some $1.79 billion to the economy in 2017–18 (ABARES 2020a). The risks associated with oil and gas exploration and extraction activities – with an estimated combined value of $36.3 billion in 2017–18 (AIMS 2021) – are being effectively managed and having a low impact on environmental condition.

Air

Australia generally enjoys good air quality; however, bushfires, drought, high winds, industrial fires and thunderstorms over the past 5 years have intensified extremes and highlighted the pressures on future air quality as the population grows and the climate changes (Figure 2). For the first time, the unprecedented bushfires that burned across 6 states over 6 months in 2019–20 made fires (including bushfires and prescribed burns) the single greatest pressure on Australia’s air quality.

The extreme impacts on air quality began when Melbourne experienced the world’s most severe thunderstorm asthma episode in 2016, causing acute breathing difficulties in thousands of people sensitive to pollen and resulting in 10 deaths. Then, following a prolonged period of drought and high temperatures associated with changing weather patterns, the summer 2019–20 bushfires created high levels of smoke for many weeks, with concentrations of PM_2.5 (particulate matter with a diameter of 2.5 micrometres or less) well above recommended air quality limits; for example, in Canberra, daily PM_2.5 concentrations on 1 January 2020 were 38.5 times the 24-hour National Environment Protection Measure (NEPM) standard. During this same extended dry period, New South Wales experienced the dustiest month (November 2019) since records began. In March 2020, the COVID-19 pandemic then triggered a dramatic shift in human activity patterns with the first of Australia’s urban ‘lockdowns’. The result was visibly improved air quality and a glimpse into a cleaner world.

Business-as-usual periods, outside these extremes, were just as important. Fine particulate matter (PM_2.5) is one of the pollutants of most concern in terms of human health, linked to 2,616 deaths in Australia each year between 2006 and 2016, or 2% of all deaths (Hanigan et al. 2021). Although all cities have maintained a ‘very good’ assessment for PM_2.5 since 2016, peak PM_2.5 levels remained above NEPM levels in all capital cities in Australia every year (Figure 3). PM_2.5 levels were stable in Darwin, Hobart and Melbourne, but deteriorated elsewhere.

For concentrations of coarser particulate matter, PM₁₀, most capital cities maintained their ‘very good’ assessment grade of 2016, and Adelaide and Darwin fell just short, moving to ‘good’. Mean PM₁₀ concentrations decreased on average. The 5-year trend in PM₁₀ assessments improved in Brisbane, Hobart, Melbourne and Perth; Canberra and Darwin were stable; and PM₁₀ levels increased in Sydney.

Indigenous communities and other vulnerable subpopulations are inequitably exposed to poorer air quality (Clifford et al. 2015). While it is well known that marked health disparities are prevalent between Indigenous and non-Indigenous Australians, understandings of environmental factors that may significantly compound health problems are under-recognised, with a recent study stating:

Socio-economic disadvantage, existing chronic cardiovascular and respiratory disease, and diabetes have all been shown to modify the effect of particulate air pollution on health outcomes. Aboriginal Australians have a high prevalence of these health risks and have been recognised as more likely to be at greater risk from poor air quality than other Australians.

Australia’s cities are hotspots for ozone, a secondary pollutant formed by chemical interactions between volatile organic compounds and nitrogen oxides (from sources such as motor vehicles, industry, stove tops and gas heaters). With the exception of Brisbane, all capital and regional cities assessed have experienced worsening levels of ozone pollution since 2016. In the 2016 assessments, Darwin, Melbourne, Perth and Sydney were ‘very good’ for ozone but were downgraded to ‘good’ in this report. Although the assessment grades in most cities remained ‘good’ and are below the air quality NEPMs, the increasing trend suggests that it will be harder to maintain this ‘good’ assessment in future.

Lead exposure has decreased in Australia in recent decades as a result of national initiatives that have restricted the addition of lead to paint and petrol, and the use of lead in consumer goods. Australia’s industrial emissions are generally well controlled, and emissions of hazardous substances such as lead and mercury have decreased. However, the National Pollutant Inventory showed that industrial emissions of many pollutants such as PM₁₀, sulfur dioxide, volatile organic compounds and mercury that had decreased since 2009 increased again in 2019, despite attempts to control them.

Urban

Australia is a highly urbanised country. As at 30 June 2021, Australia has more than 1,853 urban environments, 96% of the Australian population (around 24.5 million people) live in cities and towns, and 68% of Australians live within the greater metropolitan areas of Australia’s 8 capital cities (see also Livability). Over the past few decades, the population of major Australian cities has increased, whereas the population in remote and very remote areas has decreased. Australia’s Indigenous people make up 3.3% of the population, and many Indigenous people live in urban areas; 37.4% of Indigenous people live in capital and major cities (ABS 2017b).

The COVID-19 pandemic has substantially impacted urban environments, reducing population growth and travel, and changing lifestyles. Working from home has increased rates of walking, cycling and digital interactions (through online shopping), and travel patterns have changed. Green spaces and the desire for larger homes have also increased the demand for more suburban, urban fringe and regional development. Population growth rates are expected to return to pre-pandemic rates, along with other pressures such as consumption, pollution, congestion and waste. New technological innovations are required to move us towards a zero carbon and circular economy.

In 2020, Australia’s population density was only 3.3 people per square kilometre (people/km²), with Greater Sydney and Melbourne having the highest population densities of all Australian capital cities (estimated at 433 people/km² in Sydney and 516 people/km² in Melbourne). Australian homes are among the largest in the world; the average size increased by 6% between 2008 and 2018, from 234 to 248 square metres. The average number of occupants within an Australian home has remained relatively constant over the decade, at 2.6 people per dwelling (ABS 2019).

Indigenous communities, knowledge and aspirations are rarely reflected in the built environment, but this is changing as urban planning professionals and government planning authorities are increasing efforts to meaningfully partner with Indigenous communities to empower their rights and interests in urban settings (Parris et al. 2020). The Planning Institute of Australia developed accreditation in 2016 for ensuring Indigenous knowledge is part of planning qualifications, but, although these moves towards recognition are growing, they remain limited.

Recognising Indigenous perspective in the built environment gives back to Indigenous people, and in turn benefits all aspects of management through deeply expanded understandings of the cultural significance of waterways, past uses of Country and management practices, and sacred sites. Key to the wellbeing of Indigenous people in cities is ensuring that Traditional Owner groups are empowered to speak for Country. Connections to land and waters continue in urban areas, including in big cities (see Connection to Country).

Urban areas support critical components of biodiversity, including providing habitat for endangered species. Around 25% of all nationally listed threatened plants and 46% of nationally listed threatened animals are found in Australia’s cities and towns (ACF 2020). Indeed, 39 EPBC Act–listed species (37 plants and 2 animals) are thought to have their entire remaining distribution within only 1 or 2 cities or towns (Soanes & Lentini 2019).

Recent shifts in policy towards more green cover are countering some of the losses that occurred before 2016, yet the extent and quality of green cover in urban areas are still declining as urban areas expand. Green cover will become even more important under climate change (see Livability). Increasingly, state and local governments, communities, Indigenous people, and nongovernment organisations are playing a key role in managing and improving the green and blue networks in our urban environments by working collaboratively to reintroduce native species and plants, create urban forests and living shorelines, and instil principles of biodiversity-sensitive urban design into the design phase of urban infrastructure.

During La Niña years (see Climate), rainfall is higher than the long-term average, and in the north we experience earlier onset of the monsoon and a greater likelihood of cyclones earlier in the season. This results in increased likelihood of major damage and flooding related to strong winds, high seas and heavy rains for most of our urban environments that are located along the eastern seaboard, as experienced along the east coast of Australia in 2021. Flooding particularly affects areas built close to waterways, in low-lying areas and where there is a large amount of impervious groundcover (e.g. concrete pavements, bitumen roads). For example, Western Sydney has a high probability of flooding owing to its topography and infrastructure.

Flooding is also a challenge for many Indigenous communities, whose urban environments have been pushed to urban outskirts or land that was not claimed by others because it was prone to flooding. Many Indigenous communities may experience multiple evacuations over the course of a year, disrupting employment and education routines that are often already inconsistent. Many lower socio-economic urban areas may also be at greater risk because they may have less green cover where water can be absorbed by the soil.

Antarctica

The Antarctic region is widely regarded as of special significance because of its key role in the global climate system, its importance in oceanic food production, and its wilderness and aesthetic values. Since 2016, the overall state of the Antarctic environment has remained good, but the trend is deteriorating. Changes have continued in the range and abundance of iconic species, regional patterns in sea ice formation have shown increased variability, and the rate of melt of glaciers and ice sheets has increased. At the same time, the Antarctic region has demonstrated the effectiveness of concerted, long-term global action, with the annual hole in the ozone layer showing slow but continued evidence of shrinking following international restrictions on the use of ozone-destroying chlorofluorocarbons (Kramarova et al. 2020).

Climate change poses the most serious threat to Antarctica, the Southern Ocean and the subantarctic islands. The most important factors contributing to physical changes in the Antarctic region are the warming of the upper ocean and the lower atmosphere, and changes in atmospheric circulation, as global concentrations of greenhouse gases increase. Some aspects of surface changes have been mitigated by alteration of winds during summer through effects from the stratospheric ozone hole.

Since the 2016 state of the environment report, signals of significant change in the physical environment of the Antarctic region have been evident. Regional patterns in sea ice cover have increased in variability, and the Antarctic ice sheet and glaciers have increased their contribution to sea level rise. Additionally, important changes have continued in the state of the Southern Ocean with general freshening and warming of surface waters. Ocean acidification is of particular concern, as it threatens the long-term viability of some soft-shelled organisms that play a critical role in food webs (see Other climate-related changes).

Particular extremes of variability were apparent over the past 5 years. In 2016, Antarctic sea ice experienced a sudden and rapid decline in its seasonal cycle. By 2021, overall sea ice coverage had increased, but remained mostly below average (Figure 4). Understanding of physical processes in the Antarctic region remains incomplete, and the precise cause of this variability is still under investigation. In the 2019–20 summer, surface temperatures spiked during a record-breaking heatwave across parts of the Antarctic continent. In this case, it is apparent that large-scale climate modes played a role in the extremes, which had other widespread effects across the Southern Hemisphere, particularly in Australia.

The current rate of change in the physical environment of the Antarctic region appears to be faster than the rate at which organisms can adapt, especially those of a higher order (e.g. fish, birds). The Antarctic species most at risk are those that have adapted over millennia to a very specific and narrow range of environmental conditions, such as emperor penguins (Aptenodytes forsteri), as well as species that grow and develop slowly, or have limited capacity to move as conditions change. The potential for substantial and abrupt ecosystem shifts as a result of changing sea ice cover has been identified for nearshore Antarctic marine invertebrate-dominated communities (Clark et al. 2015).

Moss and lichen beds that have adapted over millennia to a specific, narrow range of physical conditions are the forests of Antarctica (Kennedy 1993), occupying the most extensive vegetated areas, and offering vital habitats for terrestrial invertebrates and microorganisms. But species composition is changing. In some areas, the abundance of mosses is declining, reducing habitat for associated micro-invertebrates. During the 2019–20 summer, the heatwave in parts of coastal Antarctica (Robinson et al. 2020) raised concerns about impacts on the oases of terrestrial biodiversity that inhabit the fragmented mosaic of ice-free areas, which make up just 0.44% of Antarctica’s land surface (Brooks et al. 2019).

Species adapted to warmer conditions and historically not found in the Southern Ocean are moving south and may displace subantarctic and Antarctic species through competition for food or breeding habitat. Australia’s subantarctic islands (Macquarie Island, and Heard Island and McDonald Islands) are at risk of climate-driven invasions of non-native species, particularly as increasing temperatures allow a wider range of plant species to establish themselves and may enhance plant growth. However, Macquarie Island has remained free from non-native invasive rabbits and rodents since their eradication in 2011.

Direct human impacts on Antarctica are also increasing. Before the COVID-19 pandemic, more ships and aircraft were visiting Antarctica than ever before, increasing risks of pollution with hydrocarbons (fuel, oil) through leakage and spills (Polmear et al. 2015); wildlife disturbance, including through visits to breeding areas; and noise pollution from aircrafts, ships and machinery. Just walking can cause compaction that alters the surface structure and nutrient cycles of soil and plant communities (Tejedo et al. 2014). However, management plans are in place for all protected sites in Antarctica and the subantarctic areas under Australian management.

Australia maintains 3 permanent continental Antarctic research stations (Casey, Davis and Mawson), and 1 station at subantarctic Macquarie Island. Remote field bases operate during the summer, including Wilkins Aerodrome 70 kilometres inland from Casey Station. Station populations range from 40 to 100 expeditioners over summer, and 15 to 20 over winter; some 500 expeditioners visit each season with the Australian Antarctic Program. In 2017, 29 nations collectively occupied 40 Antarctic stations year-round, and another 36 facilities operated from October to March (COMNAP 2017). Around Antarctica, the environmental footprint of stations has increased since 2016, mainly through redevelopment and expansion of existing stations.