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What is Methane?

Methane, often recognised by its chemical formula CH4, is a colourless, odourless, and highly flammable gas. It is the simplest member of the group of hydrocarbon molecules, which are compounds consisting of carbon and hydrogen atoms.

Methane is produced through both natural processes and human activities. In nature, methane is often produced by a process called methanogenesis, which is a form of anaerobic respiration used by microorganisms, often in decaying organic matter. This process happens in a variety of natural habitats, including wetlands, swamps, and the digestive systems of ruminant animals like cows and sheep.

In addition to natural processes, human activities also contribute significantly to methane production. Some of the key anthropogenic sources of methane include agriculture (particularly from livestock), waste management (landfills and waste treatment plants), and the extraction and burning of fossil fuels like coal, oil, and natural gas.

These activities have increased the concentration of methane in the atmosphere significantly since the Industrial Revolution.

How Methane Affects Our Climate

Methane is one of the most potent greenhouse gases, due in large part to its ability to trap heat in the atmosphere much more effectively than carbon dioxide (CO2). This makes methane a significant contributor to global warming and climate change, despite its relatively lower concentration in the atmosphere.

When we talk about the warming potential of a greenhouse gas, we're referring to its Global Warming Potential (GWP). GWP is a measure of how much heat a greenhouse gas traps in the atmosphere compared to CO2 over a specific period. The standard measurement periods are usually 20 years (GWP20) and 100 years (GWP100).

Methane's GWP is significantly higher than that of CO2. Over a 20-year period, methane's GWP is estimated to be around 84-87, meaning it's 84-87 times more potent at trapping heat in the atmosphere than CO2. Over a 100-year period, its GWP reduces to about 28-36 due to its shorter lifespan in the atmosphere, but it's still considerably higher than CO2.

It's important to note that while methane does not stay in the atmosphere as long as CO2 (about 12 years for methane versus centuries for CO2), the heat it traps during its time in the atmosphere accelerates the rate of warming, contributing significantly to short-term climate changes.

Moreover, when methane breaks down in the atmosphere, it forms water vapour and CO2, both of which are also greenhouse gases. This means that even after methane's initial impact, it continues to contribute to global warming in other forms.

Understanding methane's significant role in climate change is crucial to devising and implementing effective strategies for reducing greenhouse gas emissions and mitigating the impacts of climate change.

Sources of Methane

Methane is released into the atmosphere from both natural sources and human activities, known as anthropogenic sources.

IEA bar chart showing sources of methane emissions
IEA, Sources of methane emissions, IEA, Paris, IEA. Licence: CC BY 4.0

1. Natural Sources

Natural sources of methane include wetlands, termites, oceans, and other bodies of water. Wetlands are the largest natural source of methane, where it is produced by microorganisms in soils that are saturated with water and have low oxygen concentrations.

2. Agriculture

Agriculture is one of the largest anthropogenic (human-induced) sources of methane. This sector's methane emissions primarily come from enteric fermentation and manure management.

  • Enteric Fermentation

    Enteric fermentation is a natural part of the digestive process for ruminant animals such as cows, sheep, and goats. These animals have a unique, multi-chambered stomach that allows them to break down tough plant materials through a process of fermentation, which produces methane as a by-product. This methane is then released into the atmosphere primarily through belching.

  • Manure Management

    Methane is also produced during the decomposition of organic matter in manure under anaerobic (oxygen-free) conditions. The amount of methane emitted depends on factors such as the type and age of the animal, the type of feed, the temperature, and the method of manure storage and treatment.

3. Waste Management

In the waste management sector, landfills and waste treatment facilities are the main contributors to methane emissions.

  • Landfill

    When organic waste decomposes in landfills under anaerobic conditions, it produces methane. This makes solid waste landfills one of the largest sources of methane emissions in the waste sector.

  • Waste Treatment Facilities

    Wastewater treatment facilities can also produce methane. Organic matter in sewage and industrial wastewater can decompose under anaerobic conditions, similar to the process in landfills.

4. Fossil Fuel Extraction

Fossil fuel extraction, including the production, processing, storage, transmission, and distribution of coal, oil, and natural gas, contributes significantly to methane emissions

  • Coal Mining

    During the process of coal formation, methane is trapped within coal seams. During mining, this methane is released into the atmosphere. Australia, being one of the world's largest coal exporters, has significant methane emissions resulting from coal mining activities, particularly in Queensland and New South Wales.

  • Oil and Natural Gas Systems

    Methane is a primary component of natural gas. During the extraction, processing, and distribution of oil and natural gas, methane can be released through leaks or deliberate venting. In Australia, methane emissions from natural gas production, particularly from unconventional sources such as coal seam gas and shale gas, are of increasing concern.

Methane Emissions and Public Health

Methane itself is not directly harmful to human health (except at very high concentrations). However, its presence in the atmosphere contributes significantly to the formation of ground-level ozone, a key component of urban smog. This interaction between methane and other pollutants can have detrimental effects on air quality and, consequently, public health.

Ground-level Ozone and Air Quality

Methane in the atmosphere reacts with nitrogen oxides (NOx) in the presence of sunlight to form ground-level ozone, a harmful air pollutant. This is not to be confused with the ozone layer in the stratosphere, which protects the Earth from the sun's harmful ultraviolet rays.

Ground-level ozone is harmful to breathe and can cause a range of health problems, particularly in individuals with pre-existing respiratory conditions. It can cause shortness of breath, coughing, inflammation of the airways, and can worsen conditions such as asthma, bronchitis, and emphysema. Long-term exposure to ground-level ozone can lead to reduced lung function and chronic obstructive pulmonary disease (COPD).

Furthermore, high levels of ground-level ozone can also have detrimental effects on the environment, damaging crops, trees, and other vegetation, affecting ecosystems and agriculture.

Methane Emissions Policy and Regulation

Because of its impacts on global climate and human health, managing methane emissions has become a central issue in both international and domestic climate policy in recent years. Many countries, including Australia, are developing strategies and regulations aimed at reducing methane emissions to mitigate the impacts of climate change.

International Agreements

Globally, efforts to reduce methane emissions are coordinated under the framework of several international agreements:

The Paris Agreement

The Paris Agreement is a legally binding international treaty on climate change. It was adopted by 196 Parties at the UN Climate Change Conference (COP21) in Paris, France, on 12 December 2015. It entered into force on 4 November 2016.

Its overarching goal is to hold “the increase in the global average temperature to well below 2°C above pre-industrial levels” and pursue efforts “to limit the temperature increase to 1.5°C above pre-industrial levels.”

While the agreement doesn't explicitly mention methane, countries' commitments to reduce their greenhouse gas emissions under the Paris Agreement—known as their Nationally Determined Contributions (NDCs)—often include targets or plans to reduce methane emissions.

These reductions can come from a variety of sectors, including agriculture, waste management, and the extraction and use of fossil fuels. In addition, the enhanced transparency framework established by the Paris Agreement requires countries to regularly report on their emissions and efforts to reduce them.

The Global Methane Pledge

The Global Methane Pledge, initiated by the United States and the European Union in 2021, calls on countries to voluntarily take action to reduce their methane emissions by 30% by the end of the decade, compared to levels recorded in the 2020s.

The pledge has been signed by over 100 countries representing 70% of the global economy. Australia became a signatory in 2022.

If signatory nations to the Global Methane Pledge take action in accordance with the aims of the agreement, it could:

  • Prevent up to 0.2ºC of warming by 2050
  • Save up to 20 million lives by reducing air pollution
  • Create millions of jobs in the clean energy sector
  • Boost economic growth and competitiveness

Australian Methane Regulations

In Australia, the government has implemented various policies and regulations to manage and reduce methane emissions:

  • Emissions Reduction Fund (ERF)

    The ERF is the Australian government's primary policy for reducing greenhouse gas emissions. The fund provides incentives for a range of organisations and businesses to adopt new practices and technologies that reduce emissions. There are specific methods under the ERF for reducing methane emissions from landfills, coal mines, and livestock.

  • National Greenhouse and Energy Reporting (NGER) scheme

    Under this scheme, corporations that emit certain levels of greenhouse gases are required to report their emissions, energy production, and energy consumption to the government. This includes methane emissions and helps to ensure accurate accounting and monitoring of these emissions.

  • The Safeguard Mechanism

    The Australian Government's Safeguard Mechanism sets emissions limits for large emitters. If a facility exceeds its baseline emissions limit, it must offset the excess by purchasing and surrendering Australian Carbon Credit Units (ACCUs). This encourages businesses to manage their emissions within set limits.

Mitigating Methane Emissions

There are a number of strategies and technologies available that can help to reduce methane emissions, from methane capture and use to improvements in agriculture and waste management practices. With the right policies and incentives in place, these methods can be implemented across industries, as well as on individual and community levels, contributing significantly to global climate change mitigation efforts.

1. Methane Capture and Use

Methane capture and use, or methane recovery, involves capturing methane before it is released into the atmosphere and repurposing it for beneficial uses. This can be done in a variety of settings:

  • Landfills

    Landfill gas, a natural byproduct of the decomposition of organic material in landfills, is composed of roughly 50% methane. Landfill gas collection systems can capture this methane, which can then be converted and used as a renewable energy source.

  • Coal Mines

    Coal mine methane, a greenhouse gas emitted by coal mines, can also be captured and used for energy. In addition to reducing methane emissions, this practice also improves mine safety by reducing the risk of methane explosions.

  • Agriculture

    Methane digesters, or anaerobic digesters, can be used to capture methane from manure. The captured methane can then be used to generate heat or electricity, or can be cleaned and injected into natural gas pipelines.

2. Improvements in Agriculture

Agriculture is one of the major sources of methane emissions, primarily from enteric fermentation in livestock and manure management. However, various strategies can help reduce these emissions:

  • Feeding Practices

    Changes to livestock feeding practices, such as introducing feed supplements or adjusting the composition of feed, can reduce the amount of methane produced by enteric fermentation.

  • Manure Management

    More efficient manure management practices, such as using anaerobic digesters, can reduce methane emissions from livestock waste.

3. Waste Management Practices

Improvements in waste management practices can significantly reduce methane emissions from waste. For example, increasing the efficiency of waste treatment and disposal practices can reduce the amount of organic waste that ends up in landfills, thus reducing methane emissions.

4. Reductions in Fossil Fuel Extraction

Fossil fuel extraction, including oil and natural gas extraction, is a significant source of methane emissions. However, there are numerous technologies and practices that can reduce these emissions:

  • Improved Maintenance

    Regular maintenance and inspection of equipment can prevent leaks, which are a major source of methane emissions in the oil and gas industry.

  • Technology Upgrades

    Upgrading outdated systems and equipment can reduce methane emissions. For example, replacing high-bleed pneumatic devices with low- or zero-emitting devices can significantly reduce methane emissions.

  • Gas Capture

    Instead of venting or flaring excess natural gas during oil production, this gas can be captured and used, reducing methane emissions.

By implementing these strategies and technologies, we can significantly reduce methane emissions, slowing the rate of global warming and contributing to a healthier and more sustainable future for all.

Also Consider
  • Websites of relevant government agencies for information about domestic policies and regulations.
  • Non-profit and educational sites for practical tips to reduce methane emissions.