SOURCES OF GREENHOUSE GAS EMISSIONS
In Australia, most of our greenhouse emissions come from the burning of fossil fuels (coal, oil and natural gas). Fossil fuels are used mainly to generate electricity and to power transportation.
Around 95 percent of our electricity comes from fossil fuels, and the only five percent comes from renewable energy. For transport, most Australians rely on cars, buses and ferries, which require another fossil fuel; oil, to run.
The clearing of land for agriculture, mainly for beef cattle grazing, also results in significant greenhouse gas emissions in Australia. When vegetation is cleared, some of it is burned immediately, releasing CO2 into the atmosphere.
Vegetation that is not burned together with the carbon in the soil eventually decays, releasing more CO2 for many years. Emissions are measured in millions of tonnes of carbon dioxide equivalent (Mt CO2-e).
In 1990 Australia’s emissions were 457 Mt CO2-e, but by 2005 they had risen to 559 Mt CO2-e, an increase of 22 percent. However, if land clearing is excluded, emissions rise by almost 26 percent – see Figure 1.
This is because land clearing rates have dropped in Australia since 1990. In the future, therefore, if Australia’s emissions are to be reduced the reductions must come from fossil fuel use.
According to Federal Government figures, between 1990 and 2003 land clearing declined by 367,000 hectares or almost 60 percent. This is equivalent to more than 500,000 football fields. Most of this reduction was in Queensland.
What is meant by carbon dioxide equivalent?
Other greenhouse gases – like methane (CH4) and nitrous oxide (N2O) – can be converted into their equivalent to carbon dioxide using factors that compare their global warming effect.
So one tonne of methane released into the atmosphere has the same warming effect as 21 tonnes of carbon dioxide. In this way, scientists can add up the effects of various greenhouse gases and measure them all regarding their carbon dioxide equivalent (CO2-e) (see Module 1).
Carbon dioxide, the main greenhouse gas, accounted for around 74 percent of all Australia’s emissions in 2005. The two other main greenhouse gases are methane, which accounted for 20 percent, and nitrous oxide, which accounted for 4 percent – see Figure 2.
In 2005, the largest source of emissions in Australia was stationary energy that came mainly from electricity production (around 70 percent) but included direct emissions from manufacturing, metals and some other industries.
Stationary energy accounts for 50 percent of total emissions − see Figure 3. The other big contributors were transport (14 percent) and agriculture (16 percent).
HOW DO AUSTRALIA’S EMISSIONS COMPARE TO OTHER COUNTRIES?
Sometimes people argue that because Australia only contributes 1.4 percent of global greenhouse gas emissions, any move to cut emissions in Australia would make no appreciable difference.
The most obvious way to compare Australia’s emissions is to look at the absolute number. In 2005 Australia’s emissions were 525 Mt CO2-e. In comparison, the UK had emissions of 657 Mt CO2-e, France 558 Mt CO2-e, and Italy 580 Mt CO2-e. This shows that if Australia’s emissions are too small to worry about, so too are those of the UK, France and Italy.
But there is another way to compare Australia’s emissions. We can look at how much each Australian is responsible for compared to people in other countries.
This involves taking the total amount of a country’s emissions and dividing it by the number of people in that country to determine the average emissions of each person.
Figure 4 shows that Australia has the highest annual emissions per person of any industrialised country, around 27 tonnes per person. This is 30 percent higher than emissions per person in the United States (21.2 tonnes). In developing countries emissions per person are much lower – around three tonnes per person in China and one tonne in India.
There are three main reasons for Australia’s high emissions per person. First, electricity generation in Australia is very fossil fuel intensive, with coal being the main source (see Module 7).
Second, compared to many countries, Australia is not very efficient in its energy use. For example, fuel efficiency standards for cars in Australia are worse than those in China.
Finally, the mining, steel-making and aluminium smelting industries are large contributors to Australia’s total emissions. Because the Australian aluminium industry relies on coal-fired generation, the greenhouse gas emissions are around double the world average for each tonne of aluminium produced.
If wealthy nations like Australia, with high emissions per person, do not reduce their emissions it will be much more dif cult to encourage countries like China and India to reduce their emissions. (This is discussed further in Module 5 on ethics and climate change).