Different sectors of the economy, and human activities, contribute to the release and capture of greenhouse gas emissions, and the removal of such emissions in different ways and by various amounts. Of the various sectors, the energy sector produces the majority of Australia’s greenhouse gas emissions, accounting for about three-quarters (76%) of net emissions in 2008 (DCCEE 2010b).

Emissions from the energy sector increased by 44% between 1990 and 2008. Greenhouse gas emissions from the energy sector correlate with economic activity and are largely driven by population growth, economic growth and increased household income.

Within the energy sector, energy industries was the largest source of emissions (54%) relating to the combustion of fossil fuels, followed by transport activity (19%). Transport contributed 80.2 million tonnes of carbon dioxide equivalent gas or 15% of Australia’s net emissions in 2008. Emissions from the transport industry were 29% higher in 2008 than in 1990 (DCCEE 2010b). Road transport was the main source of transport emissions in 2008, accounting for 69.2 million tonnes, or 13% of national emissions. Passenger cars were the largest transport source, contributing 41.6 million tonnes (DCCEE 2010a).

The agriculture sector was the next largest contributor to Australia’s net greenhouse gas emissions. Agriculture produces most of Australia’s methane and nitrous oxide emissions. The agriculture sector emitted 58% and 76% of Australia’s methane and nitrous oxide emissions, respectively, in 2008 (DCCEE 2010b).

Emissions from the agriculture sector have stayed reasonably constant over time, with a maximum of 98.0 million tonnes in 2001 and a minimum of 84.7 million tonnes in 1993. A constant level however, has resulted in a fall in its proportion of total emissions, contributing 18.6% of total emissions in 1998 and 15.9% in 2008 (DCCEE 2010b).