The levels of some greenhouse gases in the atmosphere are being affected by human activities. This is enhancing the greenhouse effect and causing warming.
The main gases are:
- carbon dioxide (CO2)
- methane (CH4)
- nitrous oxide (N2O)
- synthetic gases (sulfur hexafluoride [SF6], hydrofluorocarbons [HFCs] and perfluorocarbons [PFCs]).
Greenhouse gases are sometimes measured in terms of their ‘carbon dioxide equivalent’ (CO2-e). CO2-e is used to compare the emissions from various greenhouse gases, based on how well they trap heat in the atmosphere. This is called their ‘global warming potential’
For example, the global warming potential for methane over 100 years is 28. This means that the warming generated by 1 million metric tons of methane is equivalent to 28 million metric tons of carbon dioxide.
Carbon dioxide is produced by burning of coal, natural gas, oil, wood, solid waste, and also by some chemical reactions. Carbon dioxide is removed from the atmosphere when it is absorbed by plants, soils and oceans.
As a result of burning fossil fuels and land clearing, carbon dioxide is being added to the atmosphere faster than plants, soils and oceans can remove it. This is causing an enhanced greenhouse effect and the acidification of our oceans.
Methane is emitted during the production and transport of coal, natural gas and oil. Methane is also produced by livestock and other agricultural processes, and by the decay of organic waste in landfills.
Nitrous oxide has 265 times the global warming potential of carbon dioxide. Nitrous oxide is released when fertilisers are applied to soils. It also comes from the burning of fossil fuels and solid waste, as well as decomposing animal manure.
Synthetic gases (SF6, HFCs, PFCs)
Synthetic gases are emitted from a variety of industrial processes. They are produced in very small quantities, but they have a very strong greenhouse effect. Thus, they are sometimes called ‘high global warming potential gases’.
SF6 has 23,500 times the global warming potential of carbon dioxide. There are different types of HFCs and PFCs, and these have up to 12,400 times the global warming potential of carbon dioxide.
Types of emissions in NSW
Most greenhouse gas emissions in NSW are produced by the energy sector. This includes:
- stationary sources, such as power stations, and manufacturing and construction industries
- mobile sources, such as road transport, trains and aeroplanes.
In 2019, around 141 megatonnes (Mt) of carbon dioxide equivalent (CO2-e) was emitted in NSW, excluding the land sector. The main sources were:
- stationary energy for electricity generation emitted 52 Mt (37% of total NSW emissions)
- transport emitted 28 Mt (20%)
- agriculture emitted 16 Mt (12%)
- stationary energy (other) emitted 15 Mt (11%)
- fugitives from fuels emitted 13 Mt (9%)
- industrial processes and product use emitted 13 Mt (9%)
- waste emitted 5 Mt (3%)
Land use, land use change and forestry reduced total NSW emissions by 5 Mt (3%) as a result of more carbon dioxide being absorbed by plants than released from land use and land clearing.
Like the rest of the world and nationally in Australia, most greenhouse gas emissions from NSW are in the form of carbon dioxide, followed by methane and nitrous oxide.
Trends in NSW emissions
Emissions from some sectors increased from 1990 to 2019:
- emissions from stationary energy for electricity generation increased from 44 Mt to 52 Mt (18%)
- transport emissions increased from 19 Mt to 28 Mt (48%)
All other sources decreased over the same period:
- land use, land use change and forestry emissions decreased from +27 Mt to −5 Mt (117%)
- fugitives from fuels emissions decreased from 25 Mt to 13 Mt (49%)
- agricultural emissions decreased from 29 Mt to 16 Mt (43%)
- waste emissions decreased from 8 Mt to 5 Mt (41%)
- stationary energy (others) emissions decreased from 17 Mt to 15 Mt (10%)
- industrial process and product use emissions decreased from 13.2 Mt to 12.8 Mt (3%)
Since 2008 emissions from electricity generation have decreased due to the growth in renewable energy generation, whereas transport emissions have continued to grow.
How NSW compares with the rest of Australia and the world
NSW performs better than much of Australia on an emissions per person basis. NSW emissions were about 18 tonnes CO2-e per person in 2018. This is below the national average of 22 tonnes per person.
NSW greenhouse gas emissions represent about one-quarter of Australia's total emissions, while NSW is home to around one-third of Australia's population.
But NSW and Australia still lag behind the rest of the world. Per-person emissions in NSW and Australia are much higher than the average for other high income countries (10 tonnes CO2-e per person, as recorded in 2016 by the World Bank).
What NSW is doing to reduce emissions
Australia is a signatory to both the Kyoto Protocol and the Paris Agreement, and our governments are working to reduce our greenhouse gas emissions.
The NSW and Australian Government have a memorandum of understanding (MoU), that sets out how the governments will work together to increase gas and electricity supply, at the same time as reducing emissions.
NSW has also developed the Net Zero Plan and Electricity Strategy within the Climate Change Policy Framework for NSW.
Net Zero Plan Stage 1: 2020–2030 is the foundation for NSW’s action on climate change. It outlines the NSW Government’s plan to deliver a 50% cut in emissions by 2030 compared with 2005 levels, laying the foundation for progressing towards net zero emissions by 2050. The plan supports various initiatives targeting:
- electricity and energy efficiency
- electric vehicles
- use of hydrogen as a transport fuel and as a replacement for fossil fuels in industry
- opportunities to reduce emissions and sequester carbon from primary industries and land management
- reduced fugitive emissions from coal mining
- reduced organic waste to landfills
- carbon financing.
The NSW Electricity Strategy is the NSW Government’s plan for reliable, affordable and sustainable electricity. The strategy includes:
- delivering Australia’s first coordinated Renewable Energy Zone
- saving energy, especially at times of peak demand
- supporting the development of new electricity generators
- setting a target to bolster the state’s energy resilience
- making it easier to do energy business in NSW.
Building on the NSW Electricity Strategy, the NSW Electricity Infrastructure Roadmap will help reduce NSW electricity emissions by 90 Mt CO2-e over the period to 2030.
The NSW Electric Vehicle (EV) Strategy will drive sales of EV to more than 50% of new car sales by 2031, preparing the NSW road network for a low-emissions future.
The NSW Climate Change Fund also provides support for local councils, households and businesses to reduce emissions, improve energy efficiency and increase climate resilience.
Trends in global emissions
Greenhouse gas production by humans has increased steadily since the Industrial Revolution in about 1750. The increase has sped up in recent decades. Global emissions have risen by approximately 42%, from 32.7 gigatonnes (Gt) of carbon dioxide equivalent (CO2-e) in 1990 to 48.9 Gt CO2-e in 2018.
Energy, namely the use of fossil fuels for power generation and transport, contributed on average 74% of annual global emissions over that period. Agriculture contributed 14%. Industrial processes and product use, waste and land use change and forestry each contributed around 4% of annual global emissions.
Over 1990-2018, on average, 73% of emissions are in the form of carbon dioxide, 19% methane, 7% N2O and 1% synthetic gases.
Source: Climate Watch, 2020.
What the world is doing to reduce emissions
There are international organisations and agreements in place to try to reduce emissions and limit climate change.
The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 to conduct objective scientific assessments on the causes, state and impacts of climate change. World renowned experts from across the globe donate their time to support the work of the IPCC.
In 1992, the United Nations Framework Convention on Climate Change (UNFCCC) was adopted as a framework for international cooperation to combat climate change.
In 1997, the third UNFCCC Conference adopted the Kyoto Protocol, the world’s first agreement to reduce greenhouse gas emissions. The Protocol binds more-developed countries to emission reduction targets. Overall, the targets add up to a 5% reduction of emissions compared with 1990 levels by 2012, and at least 18% below 1990 levels by 2020.
The Kyoto Protocol was followed by the Paris Agreement, adopted by 196 countries in 2015. The Agreement commits almost all countries to undertake efforts to address climate change and adapt to its effects. The overall goal is to limit global average temperature warming to well below 2°C, and preferably to 1.5°C, compared with pre-industrial levels.
What countries are doing to reduce emissions
Many countries have set national targets to reduce emissions.
- investing in or subsidising renewable energy sources
- closing down power stations run with fossil fuels
- setting industry limits on emissions
- expanding electric car sales and use
- reducing land clearing and deforestation
- establishing carbon trading schemes to help industry reduce emissions.
In 2017, Mission 2020, a new global carbon emissions reduction strategy, was launched by political and business leaders to increase the urgency of climate change action. It has identified milestones to be achieved in 6 sectors – energy, infrastructure, transport, land, industry and finance.
Some leaders and scientists estimate that reducing emissions will not be enough to limit climate change. They believe we also need to reduce the existing levels of greenhouse gases in the atmosphere, such as by planting new forests or using new technologies to remove carbon dioxide from the air.
Greenhouse gas emissions – NSW EPA
Greenhouse gas emissions – Our World in Data
Urgent climate action to protect our oceans – UNFCCC 2021
Global strategy to rapidly reduce emissions – Mission 2020
Climate solutions – Union of Concerned Scientists
The need for mitigation – UNFCCC