1301.0 - Year Book Australia, 2012  
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The Earth's atmosphere consists mainly of nitrogen and oxygen. It also contains smaller amounts of other gases and particles, including ozone that protects against harmful ultraviolet rays and greenhouse gases that trap some of the sun's rays and regulate the earth's surface temperature.

However, some human activities change the nature of the atmosphere, affecting air quality, levels of ultraviolet (UV) radiation and the amount of greenhouse gases (notably, carbon dioxide and methane). For example, the burning of fossil fuels (e.g. coal, oil and gas) has greatly added to the atmospheric levels of the greenhouse gas, carbon dioxide, while the clearing of forests and grasslands has reduced their capacity to remove carbon dioxide from the atmosphere.

Emissions of substances into the atmosphere are considered in this section under three main categories: greenhouse gas emissions, air pollutants and ozone depleting substances.


The main naturally occurring greenhouse gases (GHGs) in the earth's atmosphere are carbon dioxide and water vapour. The increased trapping of heat in the atmosphere arises from increasing levels of GHGs in the atmosphere. This is known as the greenhouse effect and has been linked to global warming and climate change. A 2007–08 ABS survey of households (Environmental views and behaviour, 2007–08 , 4626.0.55.001) indicated that nearly three-quarters (74%) of Australians were concerned about climate change.

The main GHGs generated by human activities are carbon dioxide, methane and nitrous oxide. Smaller amounts of hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride are also emitted. Carbon dioxide is by far the dominant GHG, accounting for about 75% when expressed as carbon dioxide equivalents (CO2-e). CO2-e is a measure used to take account of the different types of GHG emissions on a common basis.

Australia's total GHG emissions in 2009 were nearly 3% higher than in 1990 (including net emissions from land use, land use change and forestry). Carbon dioxide emissions were 3% higher, methane emissions were 5% lower, and nitrous oxide emissions were 34% higher. When Australia ratified the Kyoto Protocol, its goal was to limit net GHG emissions to 8% above the 1990 levels across the period 2008–2012. On a gross basis (i.e. excluding net emissions from land use, land use change and forestry), the change between 1990 and 2009 was 31%.

The main GHGs are described below.

Carbon dioxide

Most of Australia's carbon dioxide emissions occur as the result of fuel combustion. In 2009, fuel combustion accounted for 90% of the nation's total carbon dioxide emissions.

Between 1990 and 2009, carbon dioxide emissions from fuel combustion increased by 47%. Within the fuel combustion activities, energy industries showed an increase of 59% and transport was up 35% in this period (graph 2.32).

The energy industries, in particular electricity generation from coal-fired stations, accounted for 60% of fuel combustion emissions in 2009, up from 56% in 1990. Transport accounted for 22% of fuel combustion emissions in 2009, down from 24% in 1990.

2.32 Carbon dioxide emissions(a), Energy and transport


When expressed in CO2-e, methane comprised 20% of Australia's total GHG emissions in 2009, compared to 22% in 1990.

The digestive processes of livestock (enteric fermentation) and fugitive emissions from fuels together account for more than three-quarters of Australia's methane emissions (graph 2.33).

2.33 Main sources of methane emissions

Nitrous oxide and other gases

When expressed in CO2-e, nitrous oxide comprised 5% of Australia's total GHG emissions in 2009, compared to 4% in 1990. Nitrous oxide emissions are mainly associated with nitrogen-based fertilisers and manure use.

Very small contributions to GHG emissions are made by the hydrofluorocarbons (HFCs), the perfluorocarbons (PFCs) and sulphur hexafluoride that are used in refrigeration and air-conditioning equipment, fire extinguishers, aerosol cans and electrical equipment. The combined contribution of these gases to the total GHG emissions has been around 1% or less over the period 1990 to 2009.


The state of our air is an important factor in the quality of life. However, poor air quality can have a range of negative effects, causing health problems, reducing crop yields and harming flora and fauna. Air pollutant levels are not considered to be high in urban Australia relative to other world cities.

The main air pollutants in outdoor (or ambient) air are carbon monoxide, nitrogen dioxide, photochemical oxidants (as ozone), sulphur dioxide and particulates (dust). The National Environment Protection Measure for Ambient Air Quality (the Air NEPM) sets standards for the maximum concentrations of key air pollutants that all Australian jurisdictions are legally bound to meet.

Carbon monoxide is produced when combustion of vegetation and fossil fuels is incomplete. In 2009, agriculture generated over five times as much carbon monoxide as all other sources combined (table 2.34).

The main source of sulphur dioxide emissions is industrial activity including copper, lead, zinc, nickel and silver processing.

Nitrogen dioxide is an important air pollutant because it contributes to the formation of photochemical smog, which is another health hazard. The burning of fossil fuels (coal, oil and gas) is a major source of nitrogen dioxide.


Oxides of nitrogen(a)
Carbon monoxide
Sulphur dioxide
'000 tonnes
'000 tonnes
'000 tonnes

Electricity and heat production
1 995.33
Road transport
1 657.27
Industrial processes
1 811.28
16 238.37
. .

. . not applicable
(a) Mainly nitric oxide (NO) and nitrogen dioxide (NO2).

Source: DCC, National Greenhouse Gas Inventory 2009, Common Reporting Tables Agriculture, Energy and Industrial Processes.

Particulate matter (mainly smoke and dust) emissions are reported in the National Pollution Inventory (NPI). Two sizes of particle are measured, 10 um (micrometres) or less in diameter (PM10) and 2.5 micrometres or less in diameter (PM2.5). These particles are of a size that can be inhaled and hence pose a health hazard to humans (and animals). Besides being a health hazard, particulate matter can affect the aesthetics and utility of areas through reduction in visibility. It may also damage buildings, other structures and vegetation.

PM2.5 is mainly emitted by coal-burning electricity generating plants and by mining operations. Bushfires and dust storms add to the burden of PM10 emissions, though mining is also a large contributor. Within a given region or population centre, the exposure to these particles will vary according to local activities.

It should be noted that the measurements relate to the amounts generated at the source and therefore exposure of humans and the environment to pollution cannot be determined by the NPI. Industrial/mining emissions are estimated from reports provided by industry, while others, such as windblown dust, bushfires, and motor vehicles are estimated by state and territory authorities (table 2.35).


Source of emissions

Burning (fuel reduction, regeneration, agricultural) / Wildfires
240 000
Metal ore mining
230 000
4 200
Coal mining
220 000
5 500
Windblown dust
190 000
Paved/unpaved roads
160 000
Electricity generation
23 000
9 500
Solid fuel burning (domestic)
20 000
Motor vehicles
12 000
Basic non-ferrous metal manufacturing
9 500
1 400
Other non-metallic mineral mining and quarrying
8 100
Construction material mining
7 400
Water transport
6 900
Basic ferrous metal manufacturing
5 100
Sugar and confectionary manufacturing
4 200
2 300
Oil and gas extraction
2 200
Log sawmilling and timber dressing
1 400

na not available

Source: Department of Sustainability, Environment, Water, Population and Communities, National Pollution Inventory extracted 29/11/2011.


The ozone layer is a naturally occurring layer of the upper atmosphere where harmful ultraviolet radiation from the sun is filtered out. Ozone depleting substances (ODSs) can break down the ozone layer, allowing more harmful radiation to penetrate.

Data collected in the upper atmosphere have shown a general thinning of the earth's ozone layer, including a 5–9% depletion over Australia since the 1960s. The Antarctic ozone hole is a thinning of ozone in the stratosphere over Antarctica each spring.

The main classes of ODSs are chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons and methyl bromide. Australia was a signatory to the Montreal Protocol in 1989, whereby countries agreed to phase out the use of ODSs. The use of CFCs, traditionally used in refrigeration and aerosols, has largely been replaced by hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs), which are synthetic greenhouse gases. Emissions from HFCs and PFCs increased almost five-fold between 1990 and 2007, but in total they contribute 1% or less to Australia's total greenhouse gas emissions.


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Statistics contained in the Year Book are the most recent available at the time of preparation. In many cases, the ABS website and the websites of other organisations provide access to more recent data. Each Year Book table or graph and the bibliography at the end of each chapter provides hyperlinks to the most up to date data release where available.