Australia’s emissions of CO₂ per person in 2013 were nearly twice the average of countries in the Organisation for Economic Co-operation and Development, reflecting Australia’s heavy reliance on fossil fuels as a primary energy source, particularly the use of coal in the production of electricity. The recent Paris Agreement 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. The Australian Government ratified the Paris Agreement in November 2016 and has committed to reducing emissions to 26–28 per cent below 2005 levels by 2030. Between 1990 and 2015, Australia’s emissions decreased by 27 per cent per person.

Australian average temperatures have increased by 1 °C in the past 100 years, especially since the 1950s. The year 2013 was Australia’s warmest year on record, and the springs of 2013, 2014 and 2015 were Australia’s 3 warmest springs on record. Without mitigation, a surface temperature increase of 3.7–4.8 °C above 1850–1900 temperatures is projected for Australia.

The oceans absorb CO₂ and heat, and thus limit the rate and immediate extent of changes in climate. In recent decades, the oceans have taken up around 25 per cent of the annual anthropogenic (human) CO₂ emissions. However, the capacity of the oceans to absorb CO₂ is limited, because this absorption makes the oceans more acidic.

Resilience of a society to climate change is dependent on the sensitivity of the society to change and its capacity to adapt to change. People who are socially and economically disadvantaged are the most sensitive to climate change. Resilience through adaptation may involve significant transformations in political, economic and socio-technical systems. It is important that vulnerabilities in social resilience are reflected in national and international policies aimed at adapting to climate change.

The population of Australia’s major cities will continue to grow, meaning that human activity, and consequent power and transport requirements, will increase. This will increase air pollution.

Climate change also plays a role in air pollution. The increasing prevalence of extreme heatwaves changes the chemical reactivity of the atmosphere, promoting the formation of photochemical smog; increasing numbers of fire days will increase smoke production; an increase in heatwaves will encourage people to use cooling systems, which will place pressure on power requirements and increase emissions to the atmosphere; and reduced rainfall and drought could promote dust events.

Urban air quality is a significant cause of death and illness. There is a statistically significant relationship between higher levels of fine particles and respiratory and cardiovascular disease, and increased mortality. In 2013, the International Agency for Research on Cancer classified outdoor air pollution as a human carcinogen. There is clear evidence that even short periods of poor urban air quality have serious adverse impacts on human health.

A limitation of the standards-based approach is that there is now strong evidence that many pollutants do not have a recognised threshold below which there are no adverse health effects. Thus, the 2016 update of the Air NEPM includes a new requirement to report on a population exposure metric for fine particulate matter (PM_2.5) each year, starting in 2018. This will provide data to assess changes in population exposure and better target control measures.