At a glance
The current pressures associated with human population, catchment land use, agriculture and resource extraction are growing and will be exacerbated by the increasing pressures of climate change. The most significant climate change pressures for the coast include sea level rise, and increased frequency of cyclones and severe rainfall events. Consequences of climate-related pressures include habitat loss, disruption of ecological processes, potential species extinctions, range expansions and risk of damage to the built environment.
It is critical that Australia prepares for the coming changes as best we can, to mitigate impacts. The success of our management will ultimately determine how pressures and changes will affect the Australian coast.
In the short term (i.e. the next 5 years), the outlook for coastal issues covered in this report is mixed. The state of most biological components is stable or worsening in response to ongoing local or regional pressures, which themselves are either stable or increasing.
Growth in coastal pressures around urban centres is strongly correlated with human population growth, which shows little sign of curbing. The short-term outlook for this urban pressure will depend on whether effective ICZM can be achieved, and the success of recent risk-based approaches. Apart from the increasing evidence of a range of climate change pressures, there have been few significant new pressures on urbanised coasts in the past 5 years—most are historical or ongoing pressures that are awaiting effective management.
Exceptions to this are emerging contaminants, such as microplastics and nanoparticles. These have only recently received public attention and are poorly understood in terms of their extent, impacts and options for management. They currently lack appropriate legislation and regulation. Given the rate at which new classes of contaminants are developed and released into the environment, it is uncertain whether ecological research can assemble sufficient knowledge in time for the development of legislation to prevent serious and lasting consequences. In these cases, a precautionary approach may be most pragmatic, until such time that research can properly assess risk.
In contrast to urban areas, many remote stretches of coast are facing pressures new to the area. These pressures are related to resource extraction and processing, particularly in the north-west of Australia where significant new developments are occurring or planned. Although most extraction occurs inland or offshore, port infrastructure is required to service processing and export. Much of this infrastructure has been recently built during the mining boom, but future impacts are likely from its operation and potential expansion. There are formal, funded plans for major development of northern Australia, including agriculture, dams, mining and roads, and concern for the environment in these plans appears to be lacking. In these regions, the outlook will depend on the extent to which government and regulatory authorities manage developments and control potential environmental impacts. To some extent, these pressures will be driven by global economics and the demand for raw materials and food, but governance will ultimately determine how such pressures can affect the coast.
Species of most concern are migratory shorebirds, which, despite protection in Australia, are severely threatened by impacts on overseas habitat areas. To achieve a positive outlook, these species will require multilateral management strategies that span international boundaries—something that can be difficult to establish and even more difficult to enforce.
For other species harmed by historical or contemporary pressures, restoration of former ecosystem structure and function may be possible. This is currently being attempted for shellfish (see Box COA13) and saltmarshes (see Box COA8), and the success of these projects will be evident in coming years. Care should be taken, however, to ensure that restoration projects achieve appropriate aims for all levels of diversity, including genetic and microbial diversity, and do not have untoward outcomes by establishing overly simple (low-diversity) ecosystems.
In the longer term, the outlook for the coast could be grim, depending on mitigation and adaptation actions taken. Sustainable management of natural systems requires strategies that increase resilience and are adaptive to future rates of environmental change (Scharin et al. 2016). Effects of climate change, particularly sea level rise, will permeate the entire coast and, except for coastal engineering and global reductions in emissions, the scope for mitigation is limited. Seas are predicted to rise 0.8 metres by the end of the 21st century, inundating vast areas of coastal land and eroding even greater areas inland. Options for human settlement include managed retreat or coastal armouring, both of which come at exorbitant economic cost. In some remote areas of the coast, there may be space for coastal communities to move landwards with rising sea levels; however, this will not prevent the loss of many invaluable environmental and heritage assets.