Climate change has potentially serious implications for Australia's heritage.35 Heritage managers cannot alter climate change itself, but must respond to the symptoms or pressures that arise. In particular, opportunities should be embraced to facilitate appropriate adaptation and increase resilience as a proactive response (see Section 5).
Rising temperatures will alter ecosystems, with potentially devastating effects on niche-adapted rare and endangered species. Changes include the arrival or range expansion of other native species that are likely to have negative effects on local species.
Higher air temperatures will cause deterioration of external finishes and building fabric, as well as changes to lifestyles and cultural practices. More frequent extreme temperature events may affect the population in some areas, leading to increased human pressure on heritage sites and places, including the negative effect of abandonment.36
Higher rainfall in northern Australia may result in flooding and erosion of heritage places and archaeological sites, and possible destabilisation of historic buildings. Lower rainfall elsewhere in Australia will inevitably change vegetation communities and increase erosion, leading to destabilisation of structures and archaeological sites. It will also reduce economic viability as rural communities are abandoned because of drought.
Rising sea levels are expected to place major pressure on Australia's coastal heritage, not only on natural heritage places, but also on cultural sites such as Aboriginal middens, sea-cave deposits, archaeological sites, rock art and cave art sites. All of these are highly dependent on the maintenance and protection of their underlying landforms. Indirect pressures will arise from changes to settlement patterns, including loss of viability for some coastal areas. Changes to hydrology, soil migration and damage from storm washes may also affect historic coastal sites, such as the Sydney Opera House, as well as smaller coastal historic heritage places.36
Fire presents a major threat to reserved lands and their constituent species and ecosystems, but also to a wide variety of cultural heritage assets. Wildfire science is complex, and the pressures and impacts depend on a combination of management regimes and the responses of different plant groups.37 These factors will be affected by climate change, which will change the nature, intensity and frequency of fires.
Climate change can lead to broadscale changes in vegetation. For example, a number of eucalypt species in the Greater Blue Mountains are adapted and specialised for different climate and habitat niches.37-38 The silvertop ash (Eucalyptus sieberi) grows at altitudes from sea level to more than 1000 metres, as a tall forest tree on protected slopes or a short multistemmed tree on exposed ridges.37, 39 The wide distribution of the species makes it resilient to wildfire impact. In contrast, eucalypts that have highly restricted distributions, such as the Faulconbridge mallee ash (Eucalyptus burgessiana), are more vulnerable.
Fire management regimes and emergency response procedures have become increasingly sophisticated and responsive to the complex issues involved. While focus understandably remains on protecting people and property, natural and cultural heritage values are increasingly recognised. Wildfire abatement programs arguably reduce pressure on biodiversity, and Indigenous and historic values. In western Arnhem Land, there is mounting evidence that patchy, more traditional fire regimes are likely to have far less impact on biodiversity—particularly for long-lived, obligate seeding plants that require fire to germinate and mature rapidly following a fire, such as cypress pine (Callitris intratropica)—than the frequent intense wildfires experienced in recent decades. It is recognised that reducing the frequency of wildfires in western Arnhem Land will also better protect globally significant rock art and bush food resources.40
Climate change is likely to increase the frequency of damaging extreme climatic events such as tropical cyclones, and affect droughts and floods by changing the intensity of El niña (a periodic warming climate pattern). All these events will cause direct damage to natural and cultural heritage places. Damage and destruction may also result from rescue and clean-up activities. Some places will suffer further deterioration with a loss of economic viability, and some places and communities may be abandoned.