SoE 2003 > Atmosphere > 3.2 Climate change

3.2 Climate change

Climate is changing – mitigation and adaptation the way forward

Human activity and the combustion of fossil fuels are increasing the levels in the atmosphere of greenhouse gases such as carbon dioxide (CO₂). This is altering the overall heat balance of the atmosphere, leading to changes in climate and weather patterns, and bringing more extreme events, such as droughts, floods and cyclones. The build-up of greenhouse gases may also cause long-term changes in water availability and rises in the levels of the oceans.

The global rate of increase in the atmosphere of CO₂ concentrations over the last 200 years far exceeds the experience of the previous 20,000 years. Australia continues to have the highest per capita greenhouse gas emission rates in the world. Each person contributed the equivalent of 27.9 tonnes of CO₂ in 2000. Overall total net greenhouse gas emissions in Australia increased 6.3% between 1990 and 2000. Between 1999 and 2000 alone emissions increased by 2.1%. Most of the increases have come from energy generation, agriculture and motor vehicles.

NSW Indicators

Importance of the issue

Energy from the sun drives the earth's weather and climate and heats the planet's surface. In turn the earth radiates energy back into space. Atmospheric greenhouse gases, such as carbon dioxide (CO₂), methane and nitrous oxide, trap some of the outgoing energy, retaining heat like the glass panels of a greenhouse. This effect is a key natural element in maintaining the earth's average temperature at a comfortable level of around 15^oC. Without this natural protection, the earth's temperature would be around minus 18^oC.

Over the last few hundred years, however, changes in land-use and the burning of fossil fuels have led to much higher releases of greenhouse gases, most notably CO₂. The global atmospheric concentration of the gas has increased from 280 parts per million (ppm) in 1750 to 367 ppm in 1999, an increase of 31% (Figure 3.3). This is in comparison to what is believed were relatively stable CO₂ concentrations in the preceding several thousand years (280 ppm plus or minus 10 ppm) (IPCC 2001).

Figure 3.3 Atmospheric concentrations of carbon dioxide, Cape Grim Tasmania

Source: CSIRO Atmospheric Research data, as at 2000

These higher levels of greenhouses gases in the atmosphere are warming the earth's surface temperature, enhancing the natural greenhouse effect, and bringing changes to the climate. A continuing rise in greenhouse gas emissions is predicted to bring about global warming and an increase in extreme weather events, varying from region to region (IPCC 2001). Significant adverse impacts on Australia's natural and human systems can be expected.

The potential for the various greenhouse gases to influence climate change may be quantified by measuring their concentrations in the atmosphere in tonnes of carbon dioxide equivalent (CO₂-e). In Australia in 2000, CO₂ emissions contributed 71% of CO₂-e emissions, followed by methane with 22.6% and other gases making up the balance (AGO 2002).

Australia's total net greenhouse gas emissions increased 6.3% over the period 1990 to 2000 and by 2.1% or 11.3 million tonnes (Mt) in 1999 and 2000 alone. This makes Australia the highest emitter per capita of greenhouse gases in the world (Turton & Hamilton 2002). It should be noted, however, that there are some uncertainties in the estimates of particular emissions used in the National Greenhouse Gas Inventory (NGGI), for example, the way natural 'sinks', such as forest plantations, are accounted for.

Most of the increases in Australia's greenhouse gas emissions over the past decade have come from the generation and use of energy, agriculture, land-use changes and motor vehicles. Energy production and energy conversion (mainly coal-fired) is the main source of greenhouse gas emissions in NSW (AGO 2002).

Changes to land use through clearing, agricultural and irrigation practices are also major sources of CO₂ emissions. Land clearing in NSW is estimated to emit between 283.9 and 591.3 tonnes per hectare per year (AGO 2002). State Forests of NSW indicates that its softwood and hardwood plantations respectively sequester (or absorb) 11.1 tonnes and 11.8 tonnes of CO₂ per hectare per year. This means that in any single year not clearing one hectare of vegetation will be 24–50 times more effective at controlling greenhouse gas emissions than the absorption by plantations.

Greenhouse gas emissions from road transport have increased steadily over the last 10 years because both vehicle numbers and their use are growing. As a result, overall vehicle emissions in 2000 showed a 20.3% increase on 1990 levels.

Climate change will be apparent in parameters such as temperature, rainfall, the Southern Oscillation Index and the associated occurrences of El Niño and La Niña episodes, which cause severe droughts and flooding in eastern Australia (see Toward Environmental Sustainability 1.1).

Australian annual mean temperatures have continued to increase since 1910 with the last two decades being particularly warm. The Commonwealth Scientific and Industrial Research Organisation (CSIRO) reports that 10 of the warmest years on record have occurred during the last 20 years (CSIRO 2001). This trend is expected to continue with an increase in the average number of days over 35^oC. Sydney is projected to move from the current average of two summer days with temperatures exceeding 35^oC to between 2 and 4 days in 2030 and 3–11 days in 2070. By 2070 annual mean temperatures are expected to be 1–6^oC higher (CSIRO 2001).

Modelling by the CSIRO predicts that other likely impacts from the enhanced greenhouse effect and resulting climate change will include:

• an increase in the range of average annual rainfall in most of eastern Australia from 10% less to 10% more in 2030 and 35% less to 35% more in 2070
• an enhancement of the drying associated with the warm phase of the Southern Oscillation (El Niño) and the intense rainfall of the cool phase (La Niña).

Fewer good snowfall years and changing and reduced rainfall patterns are expected to alter the seasonal availability of irrigation and potable water and have an adverse impact on alpine tourism. Any reduced productivity in agriculture as a result will be a key concern because of the sector's importance to both the regional and national economies.

Australia's natural systems, such as vulnerable coastal and interior wetlands, montane forests, mangroves and reef systems, are likely to suffer significant and irreversible damage through climate change.

The modelling also shows that mean sea levels are likely to rise with local and seasonal variations due to changes in land-sea movements and ocean currents. The increased incidence of severe weather events, such as tropical cyclones, storm surges and flooding of rivers in outflow regions with rising sea levels, may cause significant damage to the built environment. Climate change will also extend the range and growth seasons for pests such as mosquitoes. Viruses and other pathogens are expected to accelerate the efficiency of disease transmissions.

Response to the issue

The main international response to climate change has been the development of an international treaty designed to limit global greenhouse gas emissions. In NSW the response has focused on reducing greenhouse gas emissions from the energy sector through legislated emission targets for electricity suppliers, the promotion of sustainable energy technologies and programs to reduce emissions from transport.

International and national framework

Under the United Nations Framework Convention on Climate Change (UNFCCC) of 1992, participating countries agreed to limit their greenhouse gas emissions, gather relevant information, develop strategies to adapt to climate change, and cooperate on research and technology. Australia has signed and ratified the UNFCCC. In 2002 Australia submitted its third National Communication on Climate Change to the UNFCCC, setting out the progress in implementing the country's international obligations. As part of its commitments, the Commonwealth Government has established the Australian Greenhouse Office (AGO) to coordinate domestic climate change policy and the delivery of Commonwealth programs across a range of sectors. The States and Territories are working within this national framework.

In 1997 the Kyoto Protocol was negotiated to build on the UNFCCC by setting targets to reduce emissions. Ratification of the Protocol imposes binding, quantifiable emission reduction commitments on developed countries. Australia obtained special concessions under the Kyoto Protocol allowing greenhouse gas emissions to increase 8% above 1990 emission levels up to 2010. This contrasts with most other developed nations, which agreed to limit and reduce their emissions. The Australian Government has not ratified the Protocol as it currently believes it is not in the national interest to do so. However the Government still intends to develop and invest in domestic programs to meet Australia's target without formal ratification. The United States, which is responsible for around 25% of global greenhouse emissions, has also declined to ratify.

The Kyoto Protocol will come into force when a minimum of 55 governments from the developed world agree to it and the CO₂ emissions of the ratifying countries represent at least 55% of the developed world's 1990 levels. This is expected to occur in 2003.

Since 1990, most of the increase in Australia's greenhouse gas emissions has been from electricity generation. As part of the National Greenhouse Strategy, the Commonwealth passed the Renewable Energy (Electricity) Act 2000. This legislation sets a mandatory target that 2% of Australia's electricity must be generated from renewable sources by 2010 (see Human Settlement 2.3).

NSW response

The NSW Government introduced voluntary greenhouse emission benchmarks for electricity sold in NSW in 1997. This aimed for a 5% per capita reduction in the emission levels recorded in 1989–90. Subsequent analyses, however, found low levels of compliance with the target.

In late 2002, the NSW Government introduced the Electricity Supply Amendment (Greenhouse Gas Emission Reduction) Act 2002 to make the previously voluntary benchmarks enforceable. Reduction in emissions must begin in 2003 and continue until 2007, after which per capita emissions are to be held constant at the benchmark until 2012. This is the first legislated greenhouse gas emission target in Australia and is seen as a key measure to reduce emissions. The legislation offers an opportunity for industry and government to work towards reducing greenhouse gas emissions in NSW and for industry to encourage both their domestic and commercial customers to reduce electricity demand.

Another key NSW response to curb greenhouse gas emissions was the establishment of the Sustainable Energy Development Authority (SEDA) in 1996. SEDA's role is to reduce greenhouse gas emissions and facilitate and encourage commercialisation of sustainable energy technologies. SEDA's Energy Smart Business Program focuses on reducing energy use and greenhouse gas emissions across all sectors of business (see Human Settlement 2.3). During 2001–02, SEDA estimates that this program alone reduced NSW emissions by over 400,000 tonnes of CO₂-e annually.

Reducing emissions from transport is also an important part of the response. Transport NSW and other agencies are implementing the Government's integrated transport plan for NSW. Action for Transport 2010 provides the framework and implementation program to expand and improve the quality of public transport throughout NSW (see Human Settlement 2.4). The plan, together with land-use policies such as the Integrating Land Use and Transport policy package (DUAP 2001), aims to better manage travel demand and improve integration of land use and transport development. The NSW Roads and Traffic Authority is working on a package of infrastructure, services and demand management to reduce private and commercial vehicle use.

Effectiveness of responses

The National Carbon Accounting System, established as part of Australia's obligations under the UNFCCC, indicated that changes in land use were unusually high in 1990. As this is the base year for greenhouse gas emission accounting under the UNFCCC and the Kyoto Protocol, Australia has received a generous credit of about 40 Mt of CO₂-e which it would be allowed to produce if it agreed to the Kyoto Protocol.

For the purposes of estimating greenhouse gas emissions, the figure used for total land clearing in NSW in 1990 was approximately 36,500 hectares, with CO₂ emissions of 12.6 Mt. In 1998 total CO₂ emissions from activities such as land clearing was estimated to be 6.8 million tonnes, or over 50% of 1990 levels. This apparent change in emission levels is considered to reflect the unusually high land-clearing activities in 1990 rather than abatement initiatives, salinity control or other environmental policies. It is estimated that Australia's continued growth in emissions will use the credit gained from the high 1990 baseline emissions data before 2004–05. By 2010 the National Carbon Accounting System predicts that with current policies and legislation Australia's greenhouse gas emissions will exceed 1990 levels by 11%.

The target for the first commitment period of the Kyoto Protocol is a modest but significant first step in the response to global climate change. Although uncertainty remains about the ability of ecosystems to accommodate climate change pressures, scientific advice indicates that reductions of 60–70% of today's emission levels will be needed to stabilise atmospheric greenhouse gas concentrations at levels around twice those prior to the Industrial Era (IPCC 2001).

If Australia and NSW are to meet commitments similar to those of the Kyoto Protocol, there will need to be a committed response and a large reduction in emissions to offset the current rates of emission increases. Although strategies such as the Commonwealth Renewable Energy (Electricity) Act 2000, and the NSW Electricity Supply Amendment (Greenhouse Gas Emission Reduction) Act 2002 are positive first steps, other policies and activities will be necessary to achieve the required reduction in greenhouse gas emissions.

Future directions

At a national level, ratification of the Kyoto Protocol would provide incentives and opportunities to participate in international efforts to reduce greenhouse gas emissions, using the widest range of cost-effective mechanisms.

All levels of government need to place greater priority on a coordinated program of activity to develop and implement adaptation strategies to reduce the impacts of global and regional climate change. Collaborative research with industries exposed to climate change risks will help identify adaptation strategies.

Government needs to work in partnership with industry and the community to aggressively pursue strategies to reduce the generation of energy using fossil fuels and to develop technologies, such as fuel cell vehicles.

Industry and the community have enormous opportunities to manage the consumption of energy more effectively and hence reduce emissions.

Reduced land clearing has also been identified as one of the most effective strategies for reducing greenhouse gas emissions, which would also deliver significant benefits for biodiversity.

Linked issues

2.3 Energy

2.4 Transport

3.1 Stratospheric ozone depletion

3.3 Urban air quality

6.1 Terrestrial ecosystems

6.3 Terrestrial species diversity

6.5 Fire

6.6 Aquatic ecosystems

6.7 Aquatic species diversity