Forests Australia - Fast Forest Facts

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Carbon in Australia's Forests

Australia has one of the world's highest per capita rates of greenhouse gas emissions, largely because of its reliance on fossil fuels for energy. Commercial forests and the products they produce are helping to offset Australia's total yearly greenhouse gas emissions by nearly 10%.

Forests both sequester (absorb) and emit (release) greenhouse gases. They sequester carbon dioxide from the atmosphere during plant photosynthesis and emit it, along with other greenhouse gases, by respiration and the decay or burning of plant material. In Australia, forests sequester more carbon than they emit, thereby helping to offset the country's total greenhouse gas emissions.

Carbon storage in native forests

Trees in Australia's native forests hold about 6.56 billion tonnes of carbon in their biomass (trunks, branches, leaves and roots); eucalypt woodlands and open forests contain the most (Figure 1). This carbon store is equivalent to keeping 24 billion tonnes of carbon dioxide out of the atmosphere, or 46 years worth of Australia's total 2005 net emissions from all sources. It is also equivalent to about 3.3% of all the carbon emissions arising from human activities worldwide since 1800.

Australia's forest soils are another important carbon sink: they contain about 5.51 billion tonnes of carbon, equivalent to about 39 years worth of Australia's total 2005 net greenhouse gas emissions from all sources. Casuarina and callitris woodlands contain the highest proportion of soil carbon and tropical eucalypt woodlands the lowest.

Figure 1: Carbon stored in total tree biomass (above aground plus roots) of native forest, by vegetation group, 2004 Pie chart demonstrating Figure 1: Carbon stored in total tree biomass (above aground plus roots) of native forest, by vegetation group, 2004

Greenhouse gases such as carbon dioxide and methane warm the earth by trapping infrared radiation in the atmosphere. Increasing concentrations of these gases, due mainly to the burning of fossil fuels, is believed to be causing a dramatic change in the world's climate.

Sequestration

The amount of carbon held in forests varies over time, affected by temperature and rainfall, species composition, the forest management regime, natural and human-induced disturbances such as fire and harvesting, the incidence of diseases and increases or decreases in forest area. This variation might be small compared to the total store, but it is still significant in yearly carbon accounting.

Australia's commercial native forests, plantations and wood products sequestered a net amount of 56.5 million tonnes of carbon dioxide in 2005, thereby offsetting total greenhouse gas emissions by nearly 10%. Native forests sequestered an equivalent of 5.5% of total emissions, tree plantations took in a further 3.5%, and just under 1% was stored in wood products such as house frames and furniture.

Emissions from land clearing

Conversely, land clearing for agriculture and urban development remains a significant (although declining) contributor to Australia's greenhouse gas emissions. The Intergovernmental Panel on Climate Change estimates that, globally, the land use, land-use change and forestry sector is responsible for about 20% of total carbon dioxide emissions each year, largely because of the emissions caused by the clearing and burning of forests and other vegetation. Australian emissions from land clearing, mainly for agriculture and urban development, declined from an estimated 70 million tonnes of carbon dioxide in 2002 to 53.3 million tonnes in 2005, which was more than 9% of total national greenhouse gas emissions. The rate of land clearing in Australia is likely to continue to decrease, with consequent further reductions in greenhouse gas emissions.

Net sequestration

Overall, Australia's land use, land-use change and forestry sector sequestered slightly more greenhouse gases (about 3.2 million tonnes of carbon dioxide) than it emitted in 2005, the only sector to do so (Figure 2).

Figure 2: Australia's net greenhouse emissions, by sector or subsector, 2005 Pie chart demonstrating Figure 2: Australia's net greenhouse emissions, by sector or subsector, 2005

Carbon trading

In recent years, policies have been developed to increase the carbon sequestration role of Australian forests. Several states have enacted legislation establishing property rights over carbon sequestered in tree plantations, allowing owners to trade it. In addition, the Australian Government has announced a 'cap and trade' carbon emissions trading scheme, beginning in 2010, which should help promote the nationwide trading of carbon, including that sequestered by forests.