Atmosphere Theme Report
Australia State of the Environment Report 2001 (Theme Report)
Lead Author: Dr Peter Manins, Environmental Consulting and Research Unit, CSIRO Atmospheric Research, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06746 9
Climate Variability and Change (continued)
Greenhouse gas emissions [A Indicators 1.11 and 1.12]
Carbon dioxide is the most important greenhouse gas whose concentration is rising as a result of human activity. Major sources are combustion of fossil fuels, changes in land use and industrial processes. Methane derives largely from the biosphere, particularly from livestock, rice cultivation, organic waste and landfills, as well as oil and gas exploration, gas distribution and coal mining. Ozone in the lower atmosphere arises mostly from pollutants in urban air. Nitrous oxide is emitted from agriculture, transport and some industrial processes.
The terms 'CO2 equivalent' or 'CO2-e' denote an atmospheric carbon dioxide concentration that would have the same radiative forcing effect as all of the human-produced greenhouse gases combined.
Australia is required to compile an inventory of its greenhouse gas emissions and sinks as part of its obligations under the United Nations Framework Convention on Climate Change. In the estimates of greenhouse gas emissions (excluding forest and grassland conversion) for 1998 (Figure 62), carbon dioxide accounted for 68.5% of total emissions, methane for 25.2%, nitrous oxide for 6% and PFCs for 0.3%.
Figure 62: Share of total carbon dioxide equivalent (CO2-e) emission by gas, excluding forest and grassland conversion, 1998
Source: AGO (2000a)
The main Australian sources of carbon dioxide are fossil-fuel combustion and fugitive emission from the energy sector. Stationary energy use (e.g. electricity and heat production) accounted for 56.8% of emissions, followed by agriculture 20.2%, transport 15.9%, fugitive emissions 6.9%, waste 3.4%, and industrial process 2.2% (Figure 63). The three energy-related components together account for about 80% of total emissions. Carbon dioxide removals related to forestry and other subsectors reduced the CO2-e total by over 5%.
Figure 63: Share of total carbon dioxide equivalent (CO2-e) emissions by sector, excluding forest and grassland conversion, 1998.
Source: AGO (2000a)
Stationary energy, transport and industrial processes emissions are dominated by carbon dioxide, whereas fugitive, waste and agriculture emissions are dominated by methane (Table 7). The relative share of nitrous oxide is greatest in the agricultural sector, whereas PFCs account for about one-sixth of emissions in industrial processes.
| CO2(%) | CH4(%) | N2O (%) | PFCs (%) | |
|---|---|---|---|---|
| Stationary energy | 98.9 | 0.7 | 0.4 | 0.0 |
| Transport | 94.2 | 0.7 | 5.1 | 0.0 |
| Fugitive | 18.8 | 81.1 | 0.0 | 0.0 |
| Industrial processes | 79.6 | 0.8 | 5.2 | 14.4 |
| Agriculture | 0.0 | 76.2 | 23.8 | 0.0 |
| Waste | 0.1 | 99.9 | 0.0 | 0.0 |
| All sectors | 68.5 | 25.2 | 6.0 | 0.3 |
Source: AGO (2000a).
Total greenhouse gas emissions in Australia between 1990 and 1998 (Table 8) increased 16.9% between 1990 and 1998, from 389.8 to 455.9 Mt (excluding land clearing emissions). Emissions of carbon dioxide increased 24.8%, methane emissions increased 1.8%, nitrous oxide emissions increased 24.3%, and PFC emissions fell by 70.6%. As a result of these changes, carbon dioxide increased its share of total emissions from 64.1 to 68.5%.
| 1990 (Mt CO2-e) |
1998 (Mt CO2-e) |
1990 (% of total) |
1998 (% of total) |
Changes (Mt) | Change in emissions (%) | |
|---|---|---|---|---|---|---|
| CO2 | 250.0 | 312.1 | 64.1 | 68.5 | 62.1 | 24.8 |
| CH4 | 112.9 | 114.9 | 29.0 | 25.2 | 2.0 | 1.8 |
| N2O | 22.1 | 27.5 | 5.7 | 6.0 | 5.4 | 24.3 |
| PFCs etc.A | 4.8 | 1.4 | 1.2 | 0.3 | -3.4 | -70.6 |
| Total CO2-e | 389.8 | 455.9 | 100.0 | 100.0 | 66.1 | 16.9 |
A Includes sulfur hexafluoride (SF6) from metal production.
Source: AGO (2000a).
Figures 64 and 65 show changes in greenhouse gas emissions from 1990 to 1998 and their sectoral contributions.
Figure 64: Greenhouse gas emissions per capita from 1990 to 1998
Source: AGO (2000a)
Figure 65: Greenhouse gas emissions per dollar of gross domestic product, 1990 to 1998
Source: AGO (2000a)
The National Greenhouse Strategy indicators are based on emissions, GDP and population. Although total emissions increased by 16.9% between 1990 and 1998 (Table 8), emissions per capita initially show a decrease and then an increase from 1995; by 1998, they were 6.5% higher than the 1990 level (Figures 66 and 67). Non-energy emissions per capita declined by 6.1%, from 5.3 t CO2-e in 1990 to 5.0 t CO2-e in 1998, but energy-related emissions per capita increased by 10.4% from 17.6 to 19.4 t CO2-e.
Figure 66: Emissions by gas, excluding forest and grassland conversion, 1990 to 1998.
LUC&F denotes Land Use Changes and Forestry Sector.
Source: AGO (2000a)
Figure 67: Emissions and removals by sector excluding forest and grassland conversion, 1990 to 1998.
LUC&F denotes Land Use Changes and Forestry Sector
Source: AGO (2000a)
Emissions per dollar of GDP declined by nearly 8.2% between 1990 and 1998, though emissions increased at an average rate of 2.0% per annum over this period, and economic activity grew at the rate of 3.1%. Therefore, the emission intensity of the economy declined at the rate of 1.1% per annum, with some variations over this period.
Implications
The increase in per capita energy-related emissions since 1990 is driving the total increase in emissions per capita over that period. This implies that any strategy that aims to reduce greenhouse gas emissions substantially should focus on the energy sector. Energy use efficiency continues to improve, however.