Climate change is a global problem, and minimising its impact on the Australian environment will require coordinated international action by all countries. The Paris Agreement, to which 195 countries have agreed, aims to hold the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursue efforts to limit the temperature increase to 1.5 °C. Australia ratified the Paris Agreement in November 2016.

As its contribution to global efforts, the Australian Government has committed to reducing emissions to 26–28 per cent below 2005 levels by 2030. The energy sector continues to be the dominant source of Australia’s greenhouse gas emissions, accounting for 76 per cent of net emissions in 2015. Australia’s heavy reliance on fossil fuels as a primary energy source has resulted in Australia’s per-person emission of carbon dioxide in 2013 being close to twice the average of countries in the Organisation for Economic Co-operation and Development. Australian governments at all levels are acting to reduce net emissions through a range of mechanisms, including carbon pricing, land sector mitigation, renewable energy targets and energy efficiency programs. Emissions projections reported by the Australian Government in 2015 presented a significant downwards revision in the cumulative abatement task, suggesting that Australia is on track to meeting its 2020 emissions reduction target of 5 per cent of 2000 emissions. Of note is that many of the factors that have contributed to the significant downwards revision in the cumulative abatement task are likely to change (e.g. growing seasons may improve; commodity prices may increase). Hence, the cumulative abatement task may be revised upwards in later projections. In addition, the significant debate about whether the Emissions Reduction Fund will be as effective as proposed by the Australian Government contributes to uncertainty around the cumulative abatement task presented in 2016.

Climate change will result in location-specific vulnerabilities. People who are socially and economically disadvantaged are the most sensitive to climate change. As warming increases, Australia is forecast to experience:

• increased heatwaves, leading to increased bushfire incidence and health problems (heat stress)
• longer droughts, extending further geographically than they have done in the past
• flooding from more intense storm activity
• sea level rise, leading to coastal damage
• loss of ecosystems.

An understanding of the risks associated with Australia’s climate will lead to improved action plans to adapt to the changes predicted to occur. Mitigation and adaptation are both essential for climate risk management at all scales. However, the success of climate-resilient pathways will be fundamentally linked to the effectiveness of climate change mitigation.

Human activity places significant pressure on ambient air quality through industrial emissions; vehicle and road traffic emissions; dust; and smoke from bushfires, prescribed burning and domestic wood heating. In urban centres, where air pollution is most prevalent, air quality is usually restored to acceptable levels once the immediate conditions change. However, human resilience to the effects of prolonged or recurring exposure to air pollutants is limited. Poor air quality is linked to respiratory and cardiovascular illnesses, and increased mortality.

Air quality in Australian urban centres is classified as either ‘good’ or ‘very good’. All levels of government play a role in preventing or minimising air pollutant emissions, through such measures as national air quality standards, and emissions standards for vehicles and industry. Levels of lead and nitrogen dioxide have declined markedly in all centres in recent decades. Ozone levels have remained stable since the 2011 state of the environment report. Levels of particulate matter less than 10 microns in diameter (PM₁₀) now rarely exceed the national standard. However, the advisory limit for PM_2.5 (particles less than 2.5 microns in diameter) is frequently exceeded because of extreme events such as bushfires, smog and dust storms.

The outlook for Australia’s urban air quality is generally good. Motor vehicles are the main diffuse source of air pollution in urban areas. Although the size of the Australian fleet is continuing to grow, emissions are expected to continue to decline during the next decade as a result of tighter national fuel standards and mandating of improved emission-control technologies. However, although levels of carbon monoxide, lead, nitrogen dioxide and sulfur dioxide have decreased in the past 10 years, ozone and particle levels have not declined. Moreover, climate change is expected to increase the potential for ozone, bushfire and smoke pollution. Ongoing effort will be required to secure past gains and achieve further improvements. Prospects for achieving reductions in levels of ozone and particles will be influenced by several factors, most notably:

• vehicle technology
• control of pollution from domestic wood heaters
• the extent of ongoing urban sprawl
• the availability of reliable public transport
• the impact of climate change on urban airsheds.