Everything you need to know about greenhouse gases

What is a greenhouse gas?

A greenhouse gas (GHG) is a compound present in the atmosphere that traps heat emitted by the Earth, creating a natural greenhouse effect. This process is essential for maintaining temperatures compatible with life on Earth. However, human activities, such as the burning of fossil fuels and agriculture, significantly increase the concentration of these gases, amplifying the greenhouse effect and causing global warming. 

The main GHGs include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases. These gases are responsible for the acceleration of current climate changes and affect the balance of Earth’s ecosystems.

Depending on many factors, such as energy mix, sources, country, sectors, etc, GHG emissions vary. Find out more in our article comparing GHG emissions.

The main greenhouse gases

Carbon dioxide (CO2)

Carbon dioxide (CO2) is the main greenhouse gas emitted by human activities. It is produced by the burning of fossil fuels such as coal, oil, and natural gas, as well as deforestation. CO2 is naturally present in the atmosphere, but excessive emissions increase its concentration, amplifying the greenhouse effect and contributing to global warming. CO2 accounts for about 75% of global GHG emissions, making it one of the key issues in the fight against climate change.

Methane (CH4)

Methane (CH4) is a potent greenhouse gas. Its global warming potential is much higher than that of carbon dioxide, although methane CH4 is present in smaller quantities in the atmosphere. It primarily comes from agricultural activities, such as livestock farming, organic waste management, and fossil fuel extraction. Although its lifespan in the atmosphere is shorter than that of CO2, its impact on global warming is significant.

Nitrous oxide (N2O)

Nitrous oxide (N2O) is a greenhouse gas with a global warming potential about 300 times higher than carbon dioxide over a 100-year period. It is primarily emitted by agricultural practices, particularly the excessive use of nitrogen-based fertilizers, as well as by certain industrial activities and biomass burning. Although present in smaller quantities in the atmosphere, its long lifespan and strong impact on global warming make it an important target for GHG reduction strategies.

Fluorinated gases (CFC, HFC, PFC)

Fluorinated gases, such as CFCs (chlorofluorocarbons), HFCs (hydrofluorocarbons), and PFCs (perfluorocarbons), are synthetic greenhouse gases primarily used in refrigeration, air conditioning systems, and certain industrial processes. While they are present in low concentrations in the atmosphere, their global warming potential is extremely high, sometimes thousands of times greater than CO2. CFCs, in particular, are also responsible for ozone layer depletion. Efforts to limit their use, such as the Montreal Protocol, aim to reduce their impact on climate and the environment.

The greenhouse effect and GHGs

The greenhouse effect is a natural phenomenon that allows the Earth to maintain a habitable temperature for life. Greenhouse gases (GHGs), such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases, absorb and trap heat emitted by the Earth’s surface, preventing some of this heat from escaping into space. This natural process is essential for supporting life on Earth.

However, human activities, particularly the use of fossil fuels, agriculture, and industry, significantly increase the concentrations of these gases in the atmosphere. This strengthens the greenhouse effect, causing global temperatures to rise. This phenomenon is known as global warming. Its effects are manifested through rapid climate events, such as glacier melting and rising sea levels. Understanding the role of GHGs in the greenhouse effect is essential for targeting actions needed to reduce emissions and combat climate change.

Why reduce greenhouse gas emissions?

Reducing greenhouse gas (GHG) emissions is essential for limiting the impacts of climate change. The increase in GHGs, mainly due to human activities, amplifies the greenhouse effect and accelerates global warming. This warming has dramatic consequences for the environment, such as melting glaciers, more frequent and intense droughts, floods, and storms.

The effects of climate change affect not only ecosystems but also human populations. Freshwater resources are dwindling, agricultural yields are threatened, and some regions are becoming uninhabitable, forcing millions of people to migrate. Additionally, global economies suffer significant financial losses due to the damage caused by natural disasters.

Reducing GHG emissions can slow this process and limit warming to more acceptable levels. The Paris Agreement aims to keep global temperature rise below 2°C. Acting quickly is crucial to protecting the environment, preserving natural resources, and ensuring a viable future for future generations.

Is it mandatory to report GHG emissions? Find out more in our related article.

How to measure and reduce greenhouse gas emissions?

The GHG inventory

The GHG inventory (Greenhouse Gas) is a measurement tool that allows companies and organizations to quantify the greenhouse gas emissions linked to their activities. It helps identify the sources of emissions, whether direct or indirect. This inventory is typically conducted following international standards, such as the GHG Protocol, which classifies emissions into three categories: Scope 1 (direct emissions), Scope 2 (emissions related to purchased energy), and Scope 3 (other indirect emissions).

The GHG inventory is an essential first step for any company wishing to reduce its carbon footprint. It provides a precise overview of emissions and allows for the definition of clear and optimized reduction targets. By implementing a GHG inventory, organizations can better direct their actions to contribute to the fight against global warming.

Carbon accounting

Carbon accounting is a method used to measure, track, and manage the greenhouse gas (GHG) emissions generated by a company or organization. It aims to assess direct and indirect emissions related to their activities. Carbon accounting relies on international standards such as the GHG Protocol and ISO 14064, which provide frameworks for calculating emissions.

This accounting tool is essential for helping companies make informed decisions regarding sustainability. By precisely identifying emission sources, organizations can implement targeted reduction strategies, such as improving energy efficiency, using renewable energy, or reducing resource consumption.

Additionally, carbon accounting allows companies to meet regulatory requirements and fulfill their climate commitments. It also enhances transparency, facilitating communication with stakeholders. Finally, it strengthens the brand image and reputation of the organization.

Methods for assessing and measuring emissions

The evaluation and measurement of greenhouse gas (GHG) emissions rely on standardized and internationally recognized methodologies. The most commonly used method is the GHG Protocol, which classifies emissions into three categories or “scopes”: Scope 1 for direct emissions (company activities), Scope 2 for indirect emissions related to purchased energy, and Scope 3 for other indirect emissions (supply chain, travel, etc.).

Other standards, such as ISO 14064, also provide standardized frameworks for quantifying emissions. These methods involve collecting precise data on energy consumption, travel, industrial processes, and other emission sources. Companies can use specialized software, like D-Carbonize, to facilitate the data collection, calculation, and reporting process.

These tools allow for standardized assessments and provide a comprehensive view of an organization’s carbon footprint. Once emissions are measured, reduction targets can be set and progress tracked. These methods help meet legal requirements and stakeholder expectations for climate transparency.

Strategies for reducing GHG emissions

Reducing greenhouse gas (GHG) emissions requires concrete actions tailored to the specificities of each company. The first step is to optimize energy efficiency by reducing the energy consumption of buildings, industrial processes, and infrastructure. This may include improving insulation, installing more efficient equipment, or automating certain processes.

The use of renewable energy is another effective strategy. By replacing fossil fuel energy sources with solar, wind, or hydropower, companies can significantly reduce their emissions related to energy consumption (Scope 2).

Additionally, organizations can revisit their supply chain to reduce indirect emissions (Scope 3) by choosing eco-responsible suppliers, reducing transportation distances, and adopting more sustainable materials.

Reducing waste and recycling also play an important role in decreasing the carbon footprint. Finally, carbon offsetting, through the purchase of carbon credits or participation in reforestation projects, can be used to neutralize residual emissions, offering a comprehensive approach to managing emissions.