Climate change

Climate change is affecting and threatening Australia’s heritage. Climate change effects already being seen include (see the Climate and Extreme events chapters):

  • increased temperatures
  • more frequent, intense and extensive bushfires
  • increased drought conditions
  • inundation from rising sea levels
  • more localised, but still damaging, impacts such as coastal erosion from rising sea levels and extreme weather events.

These effects are having diverse impacts across Australia and in its oceans (see the Biodiversity, Coasts, Inland water, Land and Marine chapters). Climate change effects have been noted as a potential pressure on heritage since 2009–11 (ANU 2009, SoE 2011 Committee 2011).

The International Union for Conservation of Nature (IUCN) considers that, in Oceania, climate change is one of the 2 most prevalent current threats to natural World Heritage properties (the other is invasive species). The IUCN considers that these 2 threats affect a disproportionately large number of natural World Heritage properties (Osipova et al. 2020). Expert assessment considered the threat to natural heritage of the different climate change pressures to be greatest from (McConnell 2021a):

  • rising temperatures (major threat)
  • extreme events (major threat)
  • fire (major threat)
  • sea level rise (major threat)
  • increased rainfall (moderate threat).

For geoheritage, climate change was seen as a low to moderate threat, with extreme events having the greatest impact and increased rainfall a minimal impact (McConnell 2021a) (Figures 23 and 24).

The potential impacts of climate change on cultural heritage are complex (see tables 4–5 in ICOMOS Climate Change and Cultural Heritage Working Group 2019). Very little information is available on existing impacts to cultural heritage. Expert assessment ranks climate change as the second most significant threat to Australia’s historic heritage overall, although, for Indigenous heritage, climate change is generally viewed as a moderate threat (McConnell 2021a). For historic heritage, climate change threats are seen as relatively low, except for extreme weather events (considered to be a major threat) (Figures 23 and 24) (McConnell 2021a). This view, however, does not fully reflect the situation for underwater cultural heritage, which is more threatened by rising sea levels, changes in coastal geomorphology and extreme weather events.

Although perceived as a moderate threat, climate change has caused destruction of Indigenous heritage, with lasting impacts on native species and Indigenous sites, stories, totems and traditional resources, requiring changes in cultural practices (Sheldon 2019). Some of these impacts are due to ecological shifts and seasonal changes associated with gradual climate change. The occurrence of widespread and devastating bushfires due to climate change (Fletcher et al. 2021) has a significant detrimental impact on Indigenous sites, rockshelters and rock art sites. Rock art is also damaged by emissions and pollution (Bennett 2017), and inundation has affected access to sites. Species, totems and dreaming stories are also disrupted when salt water enters freshwater habitats (see the Coasts chapter).

Figure 23 Climate change pressures considered to have the highest impact on Australia’s heritage, 2020

Figure 24 Pressures considered to have the greatest impact on Australian heritage, 2020

Assessment Climate change– driven pressures on heritage
2021 Assessment graphic showing that pressures are high, meaning they moderately degrade the state of the environment, over a moderate extent and/or with moderate severity. The situation is deteriorating.
Somewhat adequate confidence
Assessment graphic from 2011 or 2016 showing that pressures were high, meaning they moderately degrade the state of the environment, over a moderate extent and/or with moderate severity. The trend was unclear.

Climate change–driven pressures have the second greatest impact on heritage overall. Impacts are likely to worsen with increasing climate change, and because there is little effective mitigation and risk preparedness or adaptation management.
Climate change is the greatest pressure on natural heritage and the second most significant threat to Australia’s historic heritage; it is a less significant pressure on geoheritage. It is having a particularly evident and serious impact on Australia’s World Heritage.
Related to United Nations Sustainable Development Goal targets 11.4, 13.1, 13.2

Assessment Climate change impacts on Indigenous heritage
2021 Assessment graphic showing that pressures are very high, meaning they strongly degrade the state of the environment, over a large extent and with a high degree of severity. The situation is deteriorating.
Somewhat adequate confidence

Indigenous people’s heritage sites and practices are impacted by many factors, including seasonal changes, rising sea levels, drought, bushfire and invasive species.

Assessment Climate change impacts on natural heritage
2021 Assessment graphic showing that pressures are very high, meaning they strongly degrade the state of the environment, over a large extent and with a high degree of severity. The situation is deteriorating.
Somewhat adequate confidence

Increasing temperatures, marine heatwaves and other extreme events, and more intense and widespread bushfires have significantly adversely affected Australia’s natural heritage.

Assessment Climate change impacts on geoheritage
2021 Assessment graphic showing that pressures are high, meaning they moderately degrade the state of the environment, over a moderate extent and/or with moderate severity. The situation is deteriorating.
Limited confidence

Impacts on geoheritage from climate change pressures are being increasingly noticed. Documented impacts are mainly from rainfall changes and the increased incidence of bushfires. Impacts from extreme weather events and sea level rise are also of concern. Impacts on limestone and karst geoheritage are the most noticeable.

Assessment Climate change impacts on historic heritage
2021 Assessment graphic showing that pressures are high, meaning they moderately degrade the state of the environment, over a moderate extent and/or with moderate severity. The situation is deteriorating.
Somewhat adequate confidence

Extreme events and bushfires, which are increasing in severity and extent, are damaging and destroying historic heritage sites and landscape. Storm surges are also damaging coastal historic heritage. Gradual-onset changes will have a significant impact in the long term.

Assessment Climate change impacts on World Heritage
2021 Assessment graphic showing that pressures are very high, meaning they strongly degrade the state of the environment, over a large extent and with a high degree of severity. The situation is deteriorating.
Somewhat adequate confidence

Australian World Heritage has been significantly impacted by climate change. Impacts include extensive bushfire damage, extensive seagrass loss and marine species drift, and significant coral bleaching of the Great Barrier Reef.

Assessment Climate change impacts on National Heritage
2021 Assessment graphic showing that pressures are high, meaning they moderately degrade the state of the environment, over a moderate extent and/or with moderate severity. The situation is deteriorating.
Somewhat adequate confidence

Climate change impacts on Australia’s National Heritage are similar to those experienced by Australia’s World Heritage.

Extreme events

Changing fire regimes

Fire is becoming increasingly common and widespread in Australia due to climate change (Climate Council 2019). Climate-induced fire regime changes include increasing fire intensity and frequency, and changed seasonality.

Bushfires can have an adverse impact on Australia’s natural terrestrial heritage. They can impact large areas of significant plant communities and fauna habitat, and significantly reduce and displace local fauna populations. Burnt areas will recover in most areas of Australia, but some species, habitats and communities that are fire sensitive (e.g. the Gondwanan rainforests, snow gums, Tasmania’s ancient pencil pines) may never fully recover (see the Extreme events and Land chapters).

Geoheritage is less vulnerable to bushfires than are the living aspects of natural heritage. Certain types of geoheritage features may be damaged by fires, but this is usually localised, small-scale damage (e.g. spalling of exposed rock surfaces, cracking of rocks). The more significant impacts on geoheritage are likely to be from indirect effects of the fire, such as erosion resulting from vegetation loss or burial of significant landscape features. Karst (soluble rock such as limestone) landscapes are particularly sensitive to this type of impact.

Bushfires have high potential to adversely affect cultural heritage. Bushfires can damage structures, archaeological sites, landscapes, landscape features and traditional resources. Built heritage and cultural landscapes will be the most vulnerable to bushfires, as they are susceptible to intense fire if not defended. The scale and intensity of present-day bushfires mean that it will be impossible to protect against the loss of any but the most highly significant timber heritage buildings. Other timber features such as fences will be at most risk, as will fire-sensitive elements of heritage landscapes and settings.

Bushfires can also damage archaeological sites and culturally significant landscape features. Fire damage to archaeological sites will largely be superficial (e.g. accelerated decay, spalling and cracking of stone), as such sites rarely contain significant amounts of combustible material. Rock art sites are likely to be more vulnerable, as fire can spall peckings or engravings and burn pigments, and cause general damage to the rocks on which the art occurs. Archaeological heritage may be further degraded by accelerated erosion after bushfires.

Proactive fire control activities (e.g. fuel reduction burning), although designed to protect values, can have similar, albeit more localised, impacts on heritage if carried out in areas of heritage (e.g. Binskin et al. 2020). In areas subject to frequent controlled burning, the cumulative effects may be more severe.

Indigenous communities have been demonstrated to have been disproportionately affected by extreme fire events. Bhiamie Eckford-Williamson, an Euahlayi man and academic from the Australian National University, told the 2020 Royal Commission into National Natural Disaster Arrangements that 96,000 Indigenous people, including 35,000 children, were affected by the fires that burned in Queensland, New South Wales, the Australian Capital Territory and South Australia in the 2019–20 summer (Weir et al. 2020).

Historically, Indigenous people have been largely ignored in subsequent fact-finding and policy-making forums (Williamson et al. 2020). However, the effect of the 2019–20 bushfires on cultural heritage was acknowledged with some funding and support. For example, in October 2020, the Victorian Government announced that more than $4 million in grants tailored to support Indigenous cultures and healing would become available.

Other extreme events

Other extreme events such as major storms, strong winds, cyclones and floods can damage both natural and cultural heritage. However, they tend to be short-term events that cause localised damage. For natural heritage, extreme events generally have less impact overall than gradual climatic changes. However, these extreme events can still have significant impacts on heritage – for example, they can remove or damage areas of significant flora, damage small areas of habitat for important species, and damage geoheritage features though direct impacts, such as flood scour and other erosion, landslips or rockfalls. These events are likely to have limited impact in the marine environment, except in coastal areas and from marine heatwaves.

Storm-related extreme events are more likely to damage or destroy built heritage, plantings, traditional resources and some cultural landscapes, particularly where these are already in poor condition. This can be by direct impact (e.g. rain, storm damage) or indirect impacts (e.g. tree fall, accelerated erosion). Heavy rainfall promotes flooding, and accelerated soil and sediment erosion will affect a range of cultural heritage. Lightning damage is possible, but unlikely to affect a significant amount of cultural heritage.

Cyclone and tsunami events will affect marine and coastal underwater cultural heritage. These potentially cause damage through coastal erosion, ocean floor scouring, and vibration or shifting.

Sea level rise and associated marine changes

Coastal change effects will primarily be increased coastal erosion and inundation, and these will be most severe where high sea levels and storm surges occur in tandem.

Inundation due to sea level rise will be a major impact in low-lying areas – for example, the Torres Strait Islands – and will potentially affect both tangible and intangible heritage (e.g. the traditional use of coastal resources by Indigenous communities). This damage is likely to be permanent and irreversible for geoheritage values, and may be permanent or difficult to reverse for biological values (see the Marine chapter). Inundation is likely to have a higher impact on coastal built heritage than erosion, as repeated or permanent inundation can cause building flooding, fabric decay through rising damp and salting, and loss of significant gardens and plantings. Most of these impacts do not require actual inundation but may occur through higher watertables and groundwater salination.

Coastal erosion will also impact Indigenous and historic heritage, given the focus of human occupation on the Australian coast historically. It will also impact coastal maritime heritage located in areas of erosion. It is likely that these impacts will be less severe in urban areas where the coastlines have been hardened, even though there may be more historic heritage in these areas (e.g. McConnell & Evans 2017).

Long-term gradual-onset effects

Australia’s natural heritage, particularly its biological values, appears to be most vulnerable to long-term, more gradual climate changes. In Australia, these are primarily increased temperatures on land and in the ocean, ocean acidification and increased drying in some areas (see the Climate chapter). It is these changes that are causing massive coral reef bleaching, ecosystem collapse, major habitat change leading to biodiversity loss, shifts in geographical location and reductions in area of significant flora and fauna communities, and increases in invasive species and diseases.

The impact on geoheritage is likely to be significantly less than for biological values and slower to occur. However, geosystems can change over a prolonged period, resulting in widespread landscape process changes (Crofts et al. 2015). Indirect impacts are also likely (e.g. increased erosion of significant aeolian dunes and dune fields, with increased drying leading to loss of stabilising vegetation). Karst terrain is likely to be more vulnerable to climate changes and in a shorter timeframe, since small changes in temperature and moisture conditions can significantly alter karst processes.

For cultural heritage, impacts on archaeological heritage are likely to be limited, essentially to minor increased fabric deterioration. Built heritage and underwater cultural heritage are likely to be more affected, because of fabric deterioration caused by increased biodeterioration and corrosion. Some structural damage of built heritage due to changed foundation conditions can also be expected. At the landscape level, the living elements and landforms of cultural landscapes will be impacted similarly to natural heritage, while inland underwater cultural heritage can also be impacted by exposure and drying due to diminished water levels.

Case Study Climate change and the Shark Bay World Heritage Area

Sources: Professor Di Walker and Cheryl Cowell, Western Australia

Shark Bay, on the coast of Western Australia, is a 2.2 million hectare marine and terrestrial biodiverse region of ecological, geological and hydrological significance, as well as a region of exceptional beauty. Shark Bay is a World Heritage Area, with its exceptional marine environment featuring more than 120 islands.

The Outstanding Universal Values that make this a World Heritage Area include:

  • extensive seagrass beds, which are the largest (4,800 square kilometres (km2)) and the most diverse in the world
  • hypersaline environments and extreme salinity gradients
  • stromatolites, which are microbial colonies that occur as intertidal dome-shaped or mat-like deposits and are among the oldest life forms on earth; the Hamelin Pool stromatolites are the most diverse in the world
  • one of the world’s most significant and secure strongholds for the protection of dugong and many other species assemblages, including some that are found nowhere else in the wild.

However, these values are highly vulnerable to climate change, and the Shark Bay World Heritage Area has been assessed as having a low system capacity to adapt to climate change. Climate impacts are expected to threaten the resilience of areas in Shark Bay and to increasingly affect the attributes that collectively contribute to the Outstanding Universal Values. The key climate stressors identified for Shark Bay are air temperature change, storm intensity and frequency, and extreme marine heat events.

The impact of climate change is already being experienced at Shark Bay. Tropical marine life is starting to move south due to increased sea temperatures, and tiger sharks are more likely to hunt in the area. A marine heatwave in 2011 is now known to have caused a 25% loss of seagrass habitat, equivalent to a loss of 1,000 km2 of meadow. As a result, dolphin birth rates decreased, and crab, prawn and scallop populations declined. Mobile species moved into deeper water outside the protected area and were fished.

In addition, Shark Bay was subject to cyclone Seroja in 2021, which caused a storm surge in the Hamelin Pool area. This resulted in widespread flooding, which introduced terrestrial sediments. These affected the Holocene carbonate environments, which are the basis for some of the area’s Outstanding Universal Values. The cyclone also destroyed infrastructure in the area, including the viewing boardwalk located over the fragile 1,300-year-old stromatolites, with debris being spread across the stromatolites and adjacent algal mats.

These types of impact have been predicted by modelling as part of the Climate Change Vulnerability Index processes for Shark Bay. This example demonstrates the complex and cascading effects of climate change, including in tandem with existing climate-related events (e.g. cyclones). The identified and experienced high levels of vulnerability emphasise the importance of developing effective strategies for climate change adaptation at Shark Bay. This includes developing adaptation measures (which need to be based on good condition data and monitoring), underpinned by strategic adaptation and management planning.

Strategic planning is also required to balance the use of the area and protect its values. This is illustrated by the recent history of recreational fishing at Shark Bay, when areas were closed off to fishing to ameliorate pressures after the 2011 heatwave declines in some populations. These areas were recently reopened because fish populations had recovered well but, because of unusually high fish catch levels due to large domestic visitor numbers following COVID-19 pandemic lockdowns, catch limits needed to be changed to allow more recovery.

Figure 25 Stromatolites, Hamelin Pool, Shark Bay

Photo: Western Australian Department of Biodiversity, Conservation and Attractions