1301.0 - Year Book Australia, 2003  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 24/01/2003   
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Contents >> Environment >> Atmosphere and climate change

Climate change in Australia

The Earth's climate has gone through many cycles that have caused significant fluctuations in the composition of the Earth's atmosphere. These fluctuations may result in changes to rainfall, evaporation and moisture balance and cyclonic activity (Hengeveld 1991). This section discusses issues relating to the atmosphere such as temperature changes, rainfall and cyclonic activity and greenhouse gas emissions, including CO2 as well as other atmospheric pollutants.

One of the key factors indicating environmental change is temperature. Australia's annual average temperatures have increased since 1910 (graph 14.28). In general, minimum temperatures have increased the most, particularly in the eastern half of Australia where they have increased by approximately one degree Celsius (BoM 2000).

Graph - Annual mean temperature trend(a)

Australia's continental average temperature has increased by 0.7°C since 1910, with most of this increase occurring after 1950 (CSIRO 2001a). Although average temperatures have generally increased since early last century, the amount of warming has not been uniform throughout the continent, nor has it been the same for minimum and maximum temperatures. The largest increase in minimum temperatures has been in the north-east quadrant of Australia, while the largest increase in maximum temperatures has been in the north-west (BoM 2002b). Most of Australia has experienced a warming trend in annual mean temperatures over the past few decades (BoM 2002c). Environmental impacts that may result from increasing temperatures include changed rainfall patterns, effects on vegetation distribution, and the ability of areas to support land uses such as agriculture and global phenomena such as rising sea levels.

Climate change is not limited to increasing temperatures. Australia's annual mean rainfall has increased slightly over the last century. Most of this increase has been in the north-west and south-east (BoM 2002a). In 2001, preliminary data indicated that the total average rainfall across Australia was 553 mm. This amount was higher than the long-term average of 457 mm, but less than the highest level of 784 mm recorded in 1974 (BoM 2002a). The implications of these changes may include more intensive and frequent flooding, which may result in greater property damage and higher rates of erosion.

Changes have also occurred with the most destructive atmospheric activity - tropical cyclones. Trends in tropical cyclone activity in the Australian region (south of equator; 105-160° E) show that the total number of cyclones has decreased in recent decades. However, the number of stronger cyclones (minimum central pressure less than 970 hPa) appears to have increased slightly. Tropical cyclone numbers in the Australian region are influenced by the El Niño-Southern Oscillation phenomenon, and the decrease in total cyclone numbers may be associated with an increased frequency of El Niño events (BoM 2002d).

Greenhouse gas emissions

There is widespread national and international concern that it is human activities which have contributed to changes in atmospheric activity (Watson 1999). CO2 and other 'greenhouse gases' are released into the atmosphere from the use of fossil fuels, and stored carbon has also been released through the clearing of vegetation. It is thought that increasing the concentration of greenhouse gases increases the atmosphere's ability to absorb heat energy (UNEP & UNFCCC 1999). This has been termed the 'greenhouse effect' or 'enhanced greenhouse effect'. Projections indicate that annual average temperatures in Australia could be 0.4-2.0 degrees higher by 2030 and 1.0-6.0 degrees higher by 2070 (CSIRO 2002a). These estimates are based on world emissions scenarios produced by the Intergovernmental Panel on Climate Change (IPCC).

However, these scenarios have recently been challenged by Ian Castles, a former Australian Statistician. As reported in The Australian (20 August 2002), Castles wrote to the IPCC chairman that 'the economic projections used in the IPCC's emissions scenarios are technically unsound'. Castles found what he considered to be significant errors in the IPCC's Special Report on Emissions Scenarios, and he believes the IPCC's projections of emissions and therefore of temperatures are based on unrealistic assumptions and as a result have overestimated the level and impact of future economic activity.

According to the National Greenhouse Gas Inventory, Australia's total net emissions of greenhouse gases increased by 32 Mt of carbon dioxide equivalents (CO2-e) (6.3%) between 1990 and 2000. The decline of emissions during the early 1990s is due to land use changes (graph 14.29) (AGO 2002b).

Graph - Greenhouse gas emissions

As amounts of greenhouse gas emissions continue to increase, they are being reflected in the findings from atmospheric measuring stations. In the past 25 years, a steady increase in the level of CO2 has been recorded at the Cape Grim Baseline Air Pollution Station in Tasmania (graph 14.30).

Graph - Carbon dioxide measurements(a)

While total CO2-e emissions increased by 6.3% between 1990 and 2000, the emissions of individual greenhouse gases that make up this total varied significantly. Emissions of CO2 increased by 25.5%, methane emissions by 1.0% and those of nitrous oxide by 30.8% (table 14.31). Perfluorocarbons (PFC) and sulphur hexafluoride were the only greenhouse gases to record a decrease in emissions over the period (76.2% lower in 2000 than in 1990). As a result of these changes, CO2 increased its share of total emissions from about 64% to 68%.

14.31 GREENHOUSE GAS EMISSIONS, By gas (UNFCCC accounting)

Change in emissions
Greenhouse gases
Mt CO2-e
Mt CO2-e

Carbon dioxide
Nitrous oxide
Perfluorocarbons and sulphur hexaflouride
Carbon dioxide equivalent(a)

(a) Includes confidential carbon dioxide and nitrous oxide data from ammonia production and nitric acid.
(b) According to the 108% Kyoto target accounting provisions, the change in emissions between 1990 and 2000 is 5%.

Source: AGO 2002b.

The UNFCCC established the first international treaty dealing with climate change and laid the basis for global action to 'protect the climate system for present and future generations' (UNEP & UNFCCC 1999). Governments recognised the need for legally binding commitments to greenhouse gas emission limitations and reductions, which were subsequently reflected in policy terms in the Kyoto Protocol. Developed countries are committed to reducing their greenhouse gas emissions by at least 5% from 1990 levels by 2008 to 2012. In recognition of the fact that all developed countries have different economic circumstances and differing capacities to make emissions reductions, each developed country has a specific, differentiated target (AGO 2002b). Australia negotiated to restrict its emissions increases to 8% above 1990 levels by this time. Australia's 8% target includes a one-off benefit of land clearing, where reduced emissions compensate for large increases in transport and power generation.

The Kyoto Protocol is an international treaty under which developed countries (those listed in Annex B of the Protocol) have agreed to limit net greenhouse gas emissions. Many countries, including Australia, have signed (but not ratified) the Protocol. Other countries that have not ratified include New Zealand and the United States of America (UNFCCC 2002). To enter into force the Protocol must be ratified by at least 55 countries that account for at least 55% of the total CO2 emissions of developed countries in 1990. All European Union member states have either ratified, accepted or assented to the Protocol. Japan has accepted and most Pacific island states have ratified the Protocol. In September 2002, Canada, Mexico, Russia, India and China used the Earth Summit in Johannesburg to support or indicate their intention to ratify the Protocol. By August 2002, 21 of the 37 Annex I countries had ratified, accepted or assented to the Protocol. Annex I countries (including Australia, New Zealand, Japan, United States of America and the European Union) must report greenhouse gas emissions more often and in more detail.

Sources that need to be counted in the 1990 baseline are all emissions from energy, industrial processes, solvent and other product use, and changes in agriculture, waste and for some countries, including Australia, land use changes (emissions from land clearing) are also included. Approximately one-third of Australia's greenhouse gas emissions arise from the land-based sectors. The Protocol allows countries with a net source of emissions from land use change and forestry in 1990, such as Australia, to include emissions from land use change in the baseline used for calculating their assigned amounts. This mechanism was included in the Kyoto Protocol in recognition that land clearing contributes a substantial proportion of Australia’s total emissions. The trigger mechanism will allow Australia to obtain credit for efforts made to reduce emissions from land clearing.

In February 2002, the Minister for the Environment and Heritage, Dr David Kemp, announced the establishment of the Australian/US Climate Action Partnership. The Partnership would focus on such issues as emissions measurement and accounting, climate change science, stationary energy technology, engagement with business to create economically efficient climate change solutions, agriculture and land management, and collaboration with developing countries to build capacity to deal with climate change (Kemp 2002).

Greenhouse gas emissions and the Australian economy

The Australian economy is highly dependent on energy consumption. The combustion of fossil fuels is the major contributor to Australia's greenhouse gas emissions (around 64% of net emissions from stationary and transport energy combustion in 2000) (AGO 2002b). Fossil fuels provide around 90% of Australia's energy needs, a higher proportion than for most other countries or regions. The stationary energy sector (emissions from fuel combustion in energy industries such as the electricity industry) is the biggest contributor of greenhouse gases (graph 14.32), accounting for 49.3% of net emissions in 2000, with electricity generation accounting for the majority of this sector's contributions (264 Mt of CO2 equivalents). Energy use and resulting greenhouse gas emissions from the stationary energy and transport sectors are described in further detail in Energy.

Graph - 14.32 Greenhouse gas emissions(CO2-e), by sector

The industrial processes sector (emissions resulting from production processes) recorded a decrease in emissions in this period, from 12 Mt of CO2-e in 1990 to 10.3 Mt in 2000 (almost entirely a result of reduction in PFC emissions from aluminium production).

Vegetation plays an important role in reducing the level of greenhouse gases in the atmosphere, as trees and other plants absorb CO2 from the air and store it as carbon. Under ideal conditions, one million hectares of new forest could absorb about 25 Mt of CO2 a year, which would lower Australia's present CO2 production by about 9% (CSIRO 2001b). The forestry sector (including commercial forestry) is an emitter (source) and an absorber (sink) for CO2. Emissions from the forestry sector are affected by both timber harvest and forest regrowth rates. In 2000, carbon removals through the growth of forests were 23.7 Mt with forest and grassland conversion causing 64.7 Mt of emissions. Land use change and forestry provided a total of 7.1% of total net national emissions (AGO 2002b).

Current best estimates of land clearing model the emissions from burning cleared vegetation, decay of slash and below ground decay of roots, and loss of soil carbon. These estimates are highly uncertain and likely to change in the future (see the section Extent and clearing of native vegetation).

National Pollutant Inventory (NPI)

For about a decade, the Australian public has been more concerned about air pollution than about any other environmental problem. Poor air quality may lead to a number of negative impacts: it can cause health problems, damage infrastructure, reduce crop yields and harm flora and fauna. Overall, air quality in Australia is relatively good and has generally improved during the 1990s (ABS 2002b).

The NPI is an Internet database designed to provide the community, industry and government with information on the types and amounts of certain substances being emitted to the environment. The NPI is not exhaustive in its reporting of emissions, in that only emissions over a threshold from certain industries are counted. However, it does provide some quantitative measure of the amount of substances entering the environment. For example, 690 Mt of carbon monoxide, 690 Mt of nitrous oxides and 1.3 gigatonnes of sulphur dioxide were reported as released into the atmosphere for 2000-01 (table 14.33). The database also provides information about the substances listed on the NPI. It explains what the substances are derived from, what they are used for, and the risks to human health and the environment associated with them. As reporting procedures improve, this will provide for more comprehensive coverage of pollutants, allowing industry, the community and local governments to meet the interests and needs of Australians.



Carbon monoxide
Arsenic and compounds
Cyanide (inorganic) compounds
Hydrogen sulfide
Lead and compounds
Oxides of nitrogen
Sulphur dioxide

(a) Not all industries report to the NPI.

Source: NPI 2002.

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