What are Greenhouse Gas Emissions?

An overview of what greenhouse gases are and how they contribute to global warming.
What are Greenhouse Gas Emissions?
An overview of what greenhouse gases are and how they contribute to global warming.
What are Greenhouse Gas Emissions?
An overview of what greenhouse gases are and how they contribute to global warming.
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The term “greenhouse gas emissions” can sound intimidating. It simply refers to gases that trap heat in the atmosphere and contribute to climate change.

In this article, we’ll break down the basics of greenhouse gas emissions and discuss why reducing our output of these gases is essential for our planet’s continued health.

Visual depiction of greenhouse gases - Burning coal and oil, deforestation, and manufacture of products and materials like cement.

What are greenhouse gases?

Greenhouse gases are gaseous compounds in the atmosphere that absorb and emit radiation within the thermal infrared range.

These gases are naturally occurring but have been significantly increased by human activities like

  • Burning coal and oil for energy production
  • Deforestation
  • The manufacture of certain products and materials like cement

Human activities have caused an increase in atmospheric concentrations, trapping more heat and consequently leading to the current global warming phenomenon. Temperatures across vast parts of the globe are increasing due to our impact on the environment.

Why are they called greenhouse gases?

Greenhouse gases are called so because they have a warming effect on the Earth’s atmosphere, similar to how a greenhouse works. A greenhouse is a structure made of glass or transparent materials that traps heat inside, allowing plants to grow in a warm and stable environment.

In the Earth’s atmosphere, greenhouse gases act like the glass walls of a greenhouse. These gases allow shortwave solar radiation from the sun to pass through and reach the Earth’s surface, where it is absorbed and converted into heat (longwave infrared radiation). As the heat radiates back into the atmosphere, the greenhouse gases trap and absorb some of this longwave radiation, preventing it from escaping into space. This process is known as the greenhouse effect.

The trapped heat raises the temperature of the Earth’s atmosphere and surface, contributing to global warming and climate change. The term “greenhouse gases” is used to describe these gases because their warming effect on the Earth’s atmosphere is analogous to the way a greenhouse traps heat to create a warm environment for plants.

What are the specific greenhouse gases?

The six most commonly studied GHGs are

  1. Carbon dioxide
  2. Methane
  3. Nitrous oxide
  4. Hydrofluorocarbons
  5. Perfluorocarbons
  6. Sulfur hexafluoride

Carbon dioxide

Carbon dioxide, or CO2, is a common atmospheric gas and is the main contributing greenhouse gas. CO2 produces 73.8% of global emissions. It is naturally produced through the combustion of organic material and respiration and manufactured by industry through burning fossil fuels or manufacturing processes. Carbon dioxide can also be released from large bodies of water when temperatures rise, allowing algae and bacteria to consume oxygen and produce carbon dioxide instead.


Methane, CH4, is a colourless and odourless gas that is the primary component of natural gas. It is naturally produced through anaerobic digestion by bacteria, which occurs in wetlands due to the decomposition of organic material. Methane can also be produced from coal mining or oil and gas extraction and refining processes. Landfills and livestock operations are other sources of methane production.

Nitrous oxide

Nitrous oxide (N2O), commonly known as laughing gas, is a chemical compound with the formula N2O. It is a colourless, non-flammable gas that can be produced through several methods. One of the most common ways to produce nitrous oxide is by burning nitrogen and oxygen together in an engine. This process produces nitrous oxide as a byproduct of combustion. Another method of producing nitrous oxide is heating ammonium nitrate, which decomposes into nitrogen dioxide and water vapour. The nitrogen dioxide then reacts with oxygen to form nitrous oxide.


Hydrofluorocarbons, or HFCs, are artificial compounds produced from various sources. Hydrofluorocarbons can be made through a process known as ‘fluorination’, where fluorine gas is reacted with hydrocarbons to form HFCs. In addition, some industrial processes, such as manufacturing semiconductors and making foam insulation, can produce HFCs as a byproduct.


Perfluorocarbons, or PFCs, are artificial compounds that can be produced in various ways. They are usually created through a process known as ‘fluidisation’. This involves vaporised fluorocarbons that are exposed to an electric field. This process creates PFC molecules, which can be further processed and refined into usable products. PFCs can also be produced by reacting hydrocarbons with fluorine gas or by burning organic materials in the presence of fluorine gas.

Sulfur hexafluoride

Sulfur hexafluoride, or SF6, is produced by reacting sulfur with fluorine gas. This reaction produces SF6 molecules, which can then be further processed and concentrated into usable products. SF6 is also a coolant in certain industrial processes such as metal smelting, glass manufacturing and electricity generation.

Where do greenhouse gases come from?

Greenhouse gases come from a variety of sources – both natural and manufactured. Natural sources include volcanic eruptions and animal respiration. In contrast, manufactured sources include burning fossil fuels for energy production or transportation. Another source of greenhouse gas emissions is deforestation. Removing trees from forests releases large amounts of carbon dioxide into the atmosphere as those trees rot or are burned for fuel.

Most gas emissions are generated by human activities, including burning fossil fuels, producing goods with chemicals or volatile organic compounds, modifying land use patterns, and engaging in agricultural practices. Many of these activities can be traced back hundreds of years. The effects of climate change have been building up over time.

Why are greenhouse gases important?

Greenhouse gases are significant because they affect our climate on a global scale. By trapping more heat in the atmosphere, they cause temperatures to rise worldwide. This is known as global warming or climate change.

Global warming has profound implications for us all. Rising temperatures can lead to floods and droughts, extreme weather events like hurricanes and tornadoes, destruction of habitats for animals and plants alike, and much more. That’s why it’s so important to reduce greenhouse gas emissions whenever possible!

Why do we need to reduce emissions?

The concentration of atmospheric gases has been steadily increasing since industrialisation began in earnest during the 1800s.

This has caused average global temperatures to climb higher than ever recorded in human history. If left unchecked, it could have devastating consequences for life on Earth as we know it.

Already we’re seeing evidence of rising sea levels due to melting ice caps, more frequent extreme weather events such as droughts and floods, and a decrease in biodiversity due to habitat loss or destruction. All these things can be attributed to climate change caused by rising CO2 levels in the atmosphere. And all could be reduced by reducing our emissions output before it’s too late.

Illustration depicting a man cutting down emissions of CO2 from a factory with a large pair of scissors.

Why are greenhouse gases harmful?

When these gases enter the atmosphere—usually through burning fossil fuels—they trap heat from the sun and warm up our planet. This is known as “the greenhouse effect” because it is similar to how a greenhouse traps heat inside its walls to keep plants warm during colder months.

As more GHGs are released into the atmosphere, more heat is trapped, which causes global temperatures to rise significantly faster than ever before.

Rising temperatures can result in the following:

  • Changes in weather patterns.
  • Increased coastal flooding.
  • Glacier melts in polar regions.
  • Droughts in some areas while others become wetter than usual.
  • Other extreme weather events like hurricanes become more frequent.

How can we reduce greenhouse gas emissions?

The good news is that there are steps we can all take to reduce our own contribution of GHGs into the atmosphere.

One way is by reducing our reliance on fossil fuels for energy production – opting for renewable sources like wind or solar power. Reducing our consumption of animal products can have an impact too. Livestock produces large amounts of methane during their production process.

Small lifestyle changes, such as using LED lightbulbs instead of traditional bulbs, can significantly reduce your overall emissions. It may be difficult at first, but with effort and dedication, you can make a real difference in helping combat climate change!

Illustration depicting a man pushing a wheel-like clock towards the 'low emissions' side, representing strategies to reduce emissions.

How does energy production contribute to emissions?

At the core of greenhouse gas emissions is the energy sector. Approximately 44% of global emissions come from energy.

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Fossil fuels, such as coal, oil, and natural gas, are still the primary energy source for most countries. Burning them releases pollutants like carbon dioxide and harmful gases into the atmosphere. This contributes to global warming, climate change, and air pollution.

In addition to direct emissions, the energy sector contributes indirectly through related activities. Extracting, transporting and refining fossil fuels all increase emissions.

Countries have begun to embrace renewable energy sources.

Solar, wind, hydro, geothermal and ocean energy is cleaner than fossil fuels. However, according to data from the IEA, these sectors only account for 5% of total energy supply.

Increasing production from renewable energy requires investment, which not all nations can do. Beyond energy production, wealth and consumption patterns play a role in shaping emissions.

How do wealth and consumption impact greenhouse emissions?

As you would expect, wealthy societies consume more goods and services. This drives up emissions from transportation, energy production, and other sources.

Additionally, more affluent countries often have higher energy consumption. Mainly because they have more resources to invest in energy-intensive industries and lifestyles.

Consumer behaviour and consumption patterns can also drive production and influence demand. Additionally, wealth increases the choices consumers have, leading to non-sustainable decisions.

  • Individuals who prefer cars to public transport increase emissions from the transportation sector.
  • Those purchasing items made using energy-intensive processes increase emissions from the manufacturing industry.
  • Increasing demand for meat, particularly beef and lamb increases agricultural emissions. Livestock produces large amounts of methane, a potent greenhouse gas.

In fact, the wealthiest one per cent of the global population produces 37 per cent of all emissions.

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The impact of wealth on emissions is thus a positive and negative force. Capital provides the resources to reduce emissions – and lead to increased consumption.

Economic diversification and a transition to consumption-based economies is crucial to national development. Economies relying on specific sectors and exports are more prone to economic shocks. By contrast, countries encouraging domestic consumption can grow their economy more stably.

How is the economy related to emissions?

In many countries, economic growth is driven by increased energy consumption and emissions. Expansion leads to more energy needed for industrial production, transport, and other activities.

However, the relationship between the economy and emissions is complex. It can vary widely depending on several factors. For example:

  • The specific sources of energy used.
  • The efficiency of energy production and consumption.
  • The nature of the goods and services produced.

For example, export-focused economies tend to have higher emissions. Energy-intensive manufacturing emits more than service or domestic consumption economies.

End-use activities driving most energy emissions include:

  • Road transportation.
  • Residential and commercial buildings.
  • Livestock and manure.
  • Other industry.
  • Agricultural soils.

Transitioning to a net-zero world requires a complete transformation of how we produce, consume, and travel. Reducing emissions from energy production and usage will be key in averting the worst effects of climate change.

How does manufacturing affect the environment?

There are a multitude of ways manufacturing leads to increasing emissions.

  • Energy-intensive processes, such as steel, aluminium, and cement production, release carbon dioxide (CO2).
  • Producing chemicals, plastics, and other synthetic materials also releases emissions from methane (CH4) and nitrous oxide (N2O).
  • Transporting manufactured goods and raw materials also releases gases from fossil fuels.
  • The extraction of biomass, metal ores, non-metallic minerals, and fossil fuels for manufacturing can also lead to the release of greenhouse gases.

Other factors that influence greenhouse gas emissions from manufacturing include:

  • The type of energy sources used for production.
  • The energy efficiency of the production process.
  • The level of consumer demand for manufactured goods.

Promoting more sustainable manufacturing practices can reduce emissions. There is an opportunity for the sector to

  • Reduce energy consumption by improving efficiency and transitioning to renewable energy sources.
  • Promote sustainable material use and circular economies that minimise waste.

Efforts to reduce the impact of manufacturing will need to address underlying drivers. Consumer demand, market incentives, and weak governance all influence unsustainable manufacturing practices.

What is the contribution of agriculture to emissions?

Another industry that affects emissions is the agricultural sector. Many practices associated with modern agriculture increase atmospheric emissions. These include:

  • Enteric fermentation – the emission of methane gas from animals, such as cows, through belching and flatulence.
  • Synthetic fertilisers and fuel, which can release nitrogen oxide.
  • Intensive animal production.
  • Large-scale land-use changes and deforestation. Removing trees reduces the ability to absorb harmful gases and is often done by machines running on fossil fuels.

Overall, agriculture has a significant influence on greenhouse gas emissions by contributing to both direct emissions as well as indirect emissions caused by deforestation and the use of fossil fuels.

Sustainable agriculture practices could reduce the sector’s environmental impact. For instance, reducing synthetic fertilisers, improving animal management practices, and promoting regenerative agriculture.

Sustainable land use, reducing deforestation, and ensuring environmentally friendly farming would also help.

How does deforestation impact greenhouse gases?

Trees play a critical role in absorbing and storing carbon dioxide (CO2).

Clearing forests for agriculture, urbanisation, or other purposes, releases atmospheric CO2. In addition, clearing forests often leads to increased industrial activities, such as timber harvesting, mining, and burning of fossil fuels to power logging equipment.

The loss of trees also means less carbon dioxide is absorbed in photosynthesis. This reduces the impact of other initiatives. Reducing industrial emissions or changing consumption patterns will be ineffectual without forestry.

Moreover, deforestation can also reduce the overall size of forests. This can:

  • Negatively impact biodiversity.
  • Disrupt local ecosystems.
  • Lead to soil erosion, increased flooding, and other environmental impacts.

Efforts to protect forests by promoting reforestation and sustainable agriculture are needed. But, reducing deforestation also requires addressing underlying drivers. Poverty and weak governance play a part here. As does the demand for forest products and land stemming from urbanisation.

What is the influence of carbon dioxide output on the environment?

Carbon dioxide (CO2) is the primary gas contributing to emissions. According to Climate Watch data, it makes up 73.8% of all greenhouse gas emissions.

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Increased atmospheric CO2 concentrations and temperatures create various environmental impacts.

  • One of the most noticeable impacts of elevated CO2 levels is rising temperatures. This can lead to melting ice caps and glaciers, rising sea levels, heat waves, droughts, and natural disasters.
  • The warming of the ocean is also affecting marine ecosystems. Warmer water temperatures can harm coral reefs and other aquatic species.
  • Another impact of elevated CO2 levels is ocean acidification. This occurs as the ocean absorbs increasing amounts of atmospheric CO2. This can harm marine species by changing the chemistry of seawater. This makes it difficult for creatures like shellfish and coral to form and maintain their shells and skeletons.
  • Elevated CO2 levels can also change precipitation patterns and the distribution of plants and animals. Rising temperatures and changing climate conditions shift the distribution of ecosystems and biodiversity.

What role do populations play in emissions?

Population plays a role in emissions in two main ways:

  • Demographic factors such as age, education, and income.
  • The direct relationship between population size and resource consumption.

Demographic factors influence emissions through consumption patterns and energy use.

For example, older populations tend to consume less energy and emit less. Similarly, higher education and income levels tend to consume and emit more.

The population has an impact on the relative contribution to emissions. Large countries, like China, India, Brazil, and Indonesia, produce significant cumulative emissions. However, when factoring in population size, their emissions per person are negligible.

In fact, oil-rich economies and nations with severe deforestation impact the climate more. The chart below shows that Qatar, Kuwait and Bahrain have higher emissions per capita.

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The direct relationship between population size and resource consumption is straightforward. As the population grows, so does the demand for goods, services, and energy.

This increased demand drives up emissions from transportation, manufacturing, and other sectors. More resources are then extracted and processed to meet the growing demand.

What is the impact of climate change policy on emissions?

By implementing regulations, incentives, and subsidies, climate policy can:

  • Encourage the adoption of more sustainable practices and technologies.
  • Reduce the use of fossil fuels.
  • Promote the transition to renewable energy sources.

For example, policies can regulate polluting sectors and set emissions reduction targets.

Climate policy can also support the research and development of cleaner technologies. For example, carbon capture and storage or innovations in solar and wind. Lawmakers can also provide financial incentives to encourage sustainable practices. For instance, subsidising greener energy and infrastructure, like public transport and bike lanes.

However, effective climate policy requires broad-based political support and international cooperation. This involves multiple stakeholders, including governments, businesses, civil society, and individuals.

With this cooperation, it may be easier to achieve net-zero ambitions.

Collaboration for a low-carbon future: The key to addressing emissions

Greenhouse gas emissions are a major cause of global warming, posing a serious threat to the planet’s health.

These emissions trap heat in the atmosphere and cause temperatures to rise faster than ever before – leading to changes in weather patterns with devastating consequences.

To protect our planet’s health, we can take action now.

Ultimately, these efforts will depend on broad-based political support and cooperation. The willingness of individuals, businesses, and governments to take action is vital. Collaboration is essential to reduce emissions and addressing the challenges of global warming.

Photo of author


Rob Boyle
Rob built Emission Index to collect and share data, trends and opportunities to reduce our greenhouse gas emissions and expedite the energy transition.

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