Climate change: key issues

There are a number of natural influences on the world’s climate including changes to the earth’s orbit, volcanic and meteorite activity and tectonic upheaval. However, there is mounting evidence that human activity is increasing the concentration of greenhouse gases in the atmosphere, thus enhancing the greenhouse effect. Greenhouse gases have the capacity to trap heat by allowing the transmission of incoming (short-wave) radiation from the sun whilst impeding outgoing (long-wave) radiation from leaving the earth.

The greenhouse gas that is contributing most to the enhanced greenhouse effect is carbon dioxide. Fossil fuel combustion, for electricity and transport, and deforestation have increased carbon dioxide concentration to 36% above pre-industrial levels. Other greenhouse gases such as methane, nitrous oxide and water vapour also contribute significantly to the greenhouse effect.

NSW greenhouse emissions

Australia produces about 1.8% of total world greenhouse gas emissions, is the 9th largest emitter in absolute terms and has one of the highest rates of emission per person in the world. Australia’s total emissions in 2005 were 559Mt, of which 158Mt (28%) were produced by NSW. The energy sector makes the largest contribution to NSW greenhouse emissions, accounting for 71% of emissions in 2005 (111Mt).

Trend in greenhouse gas emissions from the land use, land use change and forestry sector, Kyoto Accounting method (source: AGO 2007a)

Trend in greenhouse gas emissions from the land use, land use change and forestry sector, Kyoto Accounting method (source: AGO 2007a)

Electricity generation, which was mostly coal-fired, accounted for 52% (57.8Mt) of the emissions from the energy sector. Transport and agriculture accounted for 19% (21.6Mt) and 16% (18.6Mt), respectively of the total 2005 emissions from NSW. Livestock was the largest contributor to the agricultural sector (14.5Mt), primarily resulting from methane emissions from ruminant animals. Total NSW emissions have remained relatively stable from 1990 to 2005. However, this is due to greatly reduced rates of land clearing and increased reafforestation resulting in a 13.8 Mt reduction in emissions from the Land use, land use change and forestry (LULUCF) sector, which has offset substantial increases in emissions by other sectors, particularly power generation (up 29%) and transport (up 17%).

Emission trends: 1990-2005

The national emissions profile has a similar sectoral composition to the NSW profile. The energy and agriculture sectors contribute 64 and 16%, respectively, to the national total. Emissions from LULUCF decreased by 95.2Mt CO2-e (74%) between 1990 and 2005, largely offsetting a 104Mt (36%) increase in energy sector emissions. Consequently, national emissions increased by 2.2% in that period.

Trend in greenhouse gas emissions for the energy sector, Kyoto Accounting (source: AGO 2007a)

Trend in greenhouse gas emissions for the energy sector, Kyoto Accounting (source: AGO 2007a)

It is predicted that Australia will face significant growth in emissions over the next 50 years if a “business as usual” approach is taken. There is growing consensus that it is critical to stabilise atmospheric carbon dioxide at 550 ppm or less to avoid catastrophic impacts, which will require the developed countries to reduce their emissions by 60% below 1990 levels by 2050.

The increase in emissions of greenhouse gases, particularly CO2 from combustion of fossil fuels, has altered atmospheric composition, and is increasing global temperatures and affecting global and regional climate systems. A number of changes have been observed in the NSW climate; the extent to which these can be attributed to climate change is uncertain. Temperature increased by 0.9ºC between 1910 and 2005. There are also indications that the rainfall pattern is shifting: since 2000, the State average has returned to the averages experienced in the dry first half of last century, and has been 20% lower than the average rainfall received in the second half of that century. 

Climate change and its effect on water use

Even if emissions are capped at today’s levels, some further warming is expected due to the lagged effects of past greenhouse gas emissions. Impacts on rainfall are much harder to assess but current projections suggest that it is likely to be reduced in the highly populated areas of Australia and zones of major agricultural and forestry production. Climate change is predicted to increase average temperatures in NSW by 0.7-6.4ºC by 2070, with greatest increase in the west of the State.  Rainfall is likely to decrease other than in the North East. Projections suggest a reduction in frosts and an increased incidence of hot days, bushfire and intense storms. Drought frequency may increase, especially in winter and spring. Reduced rainfall will lead to an even greater reduction in runoff, increasing pressure on water resources. These predicted impacts of climate change are likely to have serious negative impacts on all NSW primary industries, and consequently on the NSW economy.

While plant growth may be enhanced by the “CO2 fertilisation effect” and increased water use efficiency (a direct effect on plant physiology of elevated atmospheric CO2 concentration), productivity increases will be limited by water and nutrient availability. Wheat yields may be enhanced, though greater variability in average rainfall and increased incidence of drought are likely to increase yield variation. Temperature changes may alter the planting window and length of the growing season, which may restrict the options, particularly for summer crop species. Irrigated cropping is likely to be severely restricted in some years by limited water availability. Product quality is threatened by climate change, particularly in the wheat, cotton and wine industries. Growth rate of forests may be enhanced, but high risk of bushfire, and possible increase in impacts of pests and disease will threaten forest carbon stocks. Animal industries are likely to suffer increasing heat stress, affecting growth rates, egg and milk production, and reproduction. Rising sea level (due to thermal expansion of the oceans and melting of polar ice caps and mountain glaciers), storms, reduced stream flow and salt water incursion into estuaries are likely to affect fish stocks, through impact on breeding. Fisheries may also be affected by increasing acidity of the oceans. The mining industry is likely to be severely impacted by measures to mitigate emissions from coal-fired power generation.

Imperative to act

It is clear that all primary industries will be substantially affected by climate change. It is critical, therefore, that a concerted effort is made to mitigate emissions from all sectors, including the primary industries sector.  Also, knowing that some change is inevitable, the primary industries must develop capacity to adapt to climate change.

Reducing emissions (as part of an international approach) would prevent some of the worst-case scenarios of climate change occurring in Australia. All NSW primary industry sectors have a role to play in reducing emissions.  Mitigation options include capture and storage of carbon dioxide emissions from power stations; reduction in methane emissions from ruminant livestock; management of crop, pasture and forest systems to enhance carbon stocks in vegetation and soil, and to reduce N2O emissions; and use of agricultural and forest biomass for bioenergy.  Research is required to enhance available mitigation options.

Policy responses

Government has available a range of policy responses to address climate change through provision of direct or indirect incentives for implementation of available mitigation measures, from subsidies, penalties and taxes to market-based mechanisms and funding for research and education programs. All levels of government are examining available options. In NSW, the Greenhouse Plan encapsulates the current suite of policy responses. Of particular relevance to NSW DPI is emissions trading, which provides incentives for mitigation measures, and opportunities for research, extension and education.

Emissions trading

Emissions trading is considered an effective and cost-efficient means of providing an incentive for industries to efficiently reduce greenhouse gas emissions. The NSW Greenhouse Gas Abatement Scheme (GGAS) was the first mandatory emissions trading scheme in the world. The National Emissions Trading Taskforce, established by First Ministers of State and Territory Governments, has released a proposal for a national emissions trading scheme. The proposed scheme includes incentives for sequestration through reforestation and carbon capture and storage. Sequestration through soil carbon management in agricultural systems and management of existing forests are flagged for future inclusion. An emissions trading scheme will be important in providing the incentive for industry to adopt solutions developed through further research. However, further research is also required to underpin the effective operation of the emissions trading scheme itself. 

Research: past, present and future

Over the past decade, NSW DPI has been conducting research into both mitigation and adaptation strategies to limit emissions and assist with developing new systems that are sustainable in the face of climate change. The research needs can be summarised as: 

  • Developing predictive capacity, to better understand the likely impact of climate change on key NSW primary industries, at the regional scale;
  • Enhancing ability to mitigate emissions in all primary industry sectors; and
  • Developing capacity for adaptation to inevitable climate change in all primary industry sectors.