Australia’s coasts are where most of the nation’s people live, where the major cities and urban areas exist and, therefore, where the effects of human activities on local air quality are most felt.
Air quality in Australia’s major urban centres is generally good. This is due to the progressive tightening of national vehicle emission and fuel standards over the past 20 years and actions by state and territory environment protection agencies to substantially control industrial, commercial and domestic sources of air pollution. Maintenance of past gains in air quality, especially with respect to peak levels of particles and ozone, will be influenced by technological advances (such as improvements in propulsion systems for motor vehicles and clean forms of production), changes in climate and planning issues (such as transport and urban sprawl). Coastal councils around Australia are concerned about how they can manage these issues when demands on their land-rates base are rising but per capita rates are falling.
National health-based standards are rarely exceeded for prolonged periods, and very high levels of pollution are usually associated with short-lived extreme events such as bushfires and dust storms that generate very high levels of particle pollution.
Climate change is emerging as a major driver of change for Australian coasts and marine areas in the next few decades and beyond (see also Section 4 of this chapter and Chapter 6: Marine environment). Although the extent to which long-term climate change has driven pressures on coasts over the past decade is still being debated, the variability of climate (whatever its cause) has led to many incidents of inundation, erosion of coastline and damage to human lives and property. Of particular significance are sea temperature increases in the south-west, east and south-east regions, which are among the largest in the world (see Section 2.4.2). This is likely to affect commercial and recreational fishing and aquaculture, and could potentially have wider impacts on a range of coastal activities that are part of the social and economic fabric of coastal communities.
Sea level rise is emerging as a major future impact of climate change (see Section 4), but the processes affecting it have been active for some time (Figure 11.1). Over the past 25 years, the rate of sea level rise has been an order of magnitude greater than the average for several previous decades—an average rise of 3.1 millimetres per year occurred between 1993 and 2003, compared with 1.8 millimetres per year between 1961 and 2003, and 1.2 millimetres per year during the 20th century as a whole.2