What are greenhouse gases?

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Greenhouse gases are the driving cause of global climate change, and limiting global warming will depend on dramatically lowering emissions.

Greenhouse gases (GHGs) are gases in the atmosphere that contribute to the greenhouse effect and warm the planet.

Carbon dioxide (CO2), ozone (O3), methane (CH4), and nitrous oxide (N2O) are the significant gases driving the atmospheric temperature increase. According to the IPCC report, an estimated 59 billion tonnes of GHG were emitted in 2019, with a large part being carbon dioxide.

What is the definition of greenhouse gases?

Greenhouse gases (GHGs) trap part of the sun’s heat within the Earth’s atmosphere. While much of the sun’s energy reflects off the Earth’s surface and escapes back into space, greenhouse gases effectively capture some of this energy, reflect it, and thereby warm the planet. An excess of greenhouse gases in the atmosphere, driven by human activity since the industrial revolution, has led to rising temperatures and an escalating climate crisis. 

This article will explain what greenhouse gases are and why human-caused emissions fuel climate change. But before we explore greenhouse gases and the greenhouse effect, it is helpful first to understand the role of our atmosphere in regulating our Earth’s temperature.

What is the greenhouse effect?

Imagine for a moment the Earth had no atmosphere. The sun, roughly 93 million miles from Earth, sends electromagnetic radiation, warming the Earth’s surface. This warming would, in turn, release electromagnetic radiation back into space. Without an atmosphere with greenhouse gases to capture some of that heat, the energy would return to space, and the Earth would be much colder than it is today. Without the greenhouse effect, the global mean temperature would be -18°C and therefore uninhabitable for humans. 

How does our atmosphere help regulate the temperature of our planet and its climate?

The greenhouse effect occurs mostly in our troposphere, which is our lower atmosphere. Our troposphere is composed mainly of nitrogen and oxygen. Argon, carbon dioxide, water vapour, methane, and other gases are in low concentrations and comprise about 1% of the troposphere.

These gases can capture electromagnetic radiation that would otherwise be radiated back into space. These gases are known as “greenhouse gases” because they trap this energy, or heat, in the atmosphere and warm the Earth. The ability of these greenhouse gases to capture and retain heat that otherwise would have been lost, thereby warming the Earth, is called the greenhouse effect. Thanks to the greenhouse effect, our planet’s average temperature is a comfortable 15°C. 

How do we measure the potency of greenhouse gases?

While carbon dioxide, water vapour, and methane are the most commonly known, many other greenhouse gases exist. Some occur in nature, and others are industrial. Greenhouse gases are described using two main indicators: Global Warming Potential - a relative measure of how much heat a greenhouse gas traps in the atmosphere; and the atmospheric lifetime - which measures the lifetime of the gas in the atmosphere.

The first indicator expresses itself in CO2 equivalent (how much more or less the effect on the climate is of this greenhouse gas compared to the CO2 effect set as a reference equal to 1). This effect on the climate is known as the global warming potential, or GWP. GWP is defined as the amount of heat absorbed by any greenhouse gas in the atmosphere as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (CO2). The second indicator, atmospheric lifetime, indicates the time it takes for the gas to disappear from the atmosphere.  

You can get a preliminary idea of your company’s greenhouse gas emissions by using Plan A’s free carbon scanner

What are some greenhouse gases to be familiar with?

Carbon dioxide (or CO2) is a colourless, odourless gas consisting of one part carbon and two parts oxygen. CO2 is a natural component of our planet's atmosphere and is one of the most commonly known greenhouse gases. 

Because humanity releases more carbon dioxide –primarily through burning fossil fuels like coal and oil– into the atmosphere than current biological processes can remove, the amount and concentration of carbon dioxide in the atmosphere and ocean increases yearly.

Methane (CH4), a primary constituent of natural gas, is a greenhouse gas, and its presence in the atmosphere affects our climate system and the Earth's temperature.

Although CO2 has a longer-lasting effect on our climate, methane has a much higher Global Warming Potential (GWP) than carbon dioxide.

According to the Environmental Defence Fund, methane accounts for at least 25% of today's global warming. Agriculture (primarily through manure and gastroenteric releases, but also through rice cultivation) is responsible for around a quarter of the methane emissions, followed by the energy sector.

Nitrous oxide (N2O), also known as laughing gas, contributes to the greenhouse effect.

In addition to natural sources, agriculture and fertilisers produce nitrous oxide. Around 40% of the total N2O emissions globally come from human activities. The IPCC has calculated that nitrous oxide comprises about 6% of all greenhouse gas emissions, and its emissions rose 30% in the past forty years.

Water Vapor is Earth’s most abundant greenhouse gas and is responsible for about half of Earth’s greenhouse effect. As temperatures increase, the rate of water evaporation also increases. This water vapour remains in the lower atmosphere, where it absorbs radiation and pushes it down to the Earth’s surface, causing already hot temperatures to continue to rise. This creates a feedback loop, as water vapour is a greenhouse gas that becomes more abundant the warmer the planet becomes. 

Hydrofluorocarbons refrigerants are found in everything from air conditioning systems to home refrigerators,  grocery store freezers, and industrial warehouses. The majority of the gases used in refrigerants are hydrofluorocarbons, or HFCs. HFCs are hundreds to thousands of times more potent a greenhouse gas than carbon dioxide. Therefore, limiting the emissions of these gases is crucial to limit global warming, as is ensuring their safe disposal.

Sulfur hexafluoride: The most dangerous greenhouse gas

Sulfur hexafluoride (SF6) is the most potent of all greenhouse gases, with a global warming potential 23,900 times the baseline of CO2. SF6 is synthetic and does not have a natural sink or effective disposal methods. Thus, when emitted, SF6 simply accumulates in the atmosphere. SF6’s atmospheric lifetime can be up to 3,200 years, well beyond CO2‘s atmospheric lifetime. 

The energy industry is SF6’s biggest consumer– it consumes more than 80% of the gas. SF6 is mostly used inside switchgear – an essential component of any electricity grid.  They are also used inside wind turbines, meaning neither wind energy, nor electricity, in general, can be claimed to be completely environmentally friendly.

What do greenhouse gases have to do with climate change?

The greenhouse effect is a natural part of our planet, and it keeps our average mean temperature steady, allowing life to flourish. So why is it associated with climate change and global warming? This is due to human activity, which has raised the amount of greenhouse gases in the atmosphere to unnaturally high levels. Humanity has been amplifying the greenhouse effect since the industrial revolution by burning oil, coal and natural gas for energy.

The emissions from these fossil fuels is drastically altering our atmosphere’s composition. Unfortunately, our global economy currently relies on fossil fuels for energy. To solve the climate crisis and reverse global warming, there is an urgent need to decarbonise business. You can find out where your business stands regarding emissions with Plan A’s end-to-end decarbonisation software

The burning of fossil fuels, changes in land use, the creation of potent new molecules, industrial farming practices, deforestation, and the use of artificial fertilisers are among the human activities leading to an increase in greenhouse gases in the atmosphere. Over the last 100 years, the level of greenhouse gases in the atmosphere has risen by 25%. According to the IPCC, an estimated 59 billion tonnes of GHG were emitted in 2019, largely carbon dioxide. 

What do greenhouse gases have to do with climate change?
Greenhouse gas concentrations levels have skyrocketed above pre-industrial levels.
Source: Climate Central

How have rising greenhouse gases impacted our climate?

Due to the increase in greenhouse gas emissions, the planet’s average temperature has already risen by 1.2°Celsius since pre-industrial times. This may not seem like a lot on a planet whose climate ranges from that of Antarctica to that of the Sahara, but this variation has already had devastating impacts on our planet’s ecosystems, landscapes, and day-to-day life. The most immediate, perceptible symptoms are natural disasters such as droughts, floods, and wildfires. According to the UN’s disaster-monitoring system, the number of natural disasters has almost quadrupled since 1970.

In recap, here are some important points to remember about greenhouse gases:

  • Greenhouse gases trap heat in the atmosphere
  • The greenhouse effect is a natural process that has allowed life to flourish on earth
  • However, the burning of fossil fuels have led to an excessive amount of greenhouse gases in the atmosphere
  • Global warming is caused by these excess greenhouse gases
  • Decarbonisation, or the reduction of greenhouse gases being emitted through human activities, is essential to stop global warming

How can we solve the problem of excessive greenhouse gases in our atmosphere?

The science is clear: Greenhouse gases are being emitted into the atmosphere at alarming rates, raising the Earth’s temperature and driving catastrophic climate change. It seems everywhere we turn, there are new natural disasters and disruptions. But there is a silver lining: we know exactly what drives this crisis and what needs to be done. Decarbonisation stops emissions from being released in the first place and carbon sequestration captures and stores the excess carbon in the atmosphere. Both are essential solutions to the climate crisis. 

What role can businesses play in lowering greenhouse gas emissions?

The ways we do business are currently emitting dangerous amounts of greenhouse gases into our Earth’s atmosphere. However, business sustainability strategies such as carbon accounting and implementing science-based decarbonisation targets can be powerful levers for change. 

Some ways a business can lower its emissions are:

  • Switching to a renewable energy provider
  • Moving events online and avoiding air travel
  • Encouraging employees to bike or ride public transit to the office
  • Switching your vehicle fleet to electric
  • Managing waste efficiently

Plan A knows that every fossil fuel that remains in the ground, every refrigerant that is not released into the atmosphere, and every kilowatt of energy saved makes a difference. We work with companies to track, measure, and lower their emissions.

Your business can be part of the solution. Sign up for a free demo today and learn how you can lower your greenhouse gas emissions and bring your business to net-zero.

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