Greenhouse effect and greenhouse gases

Most of the GHGs come from natural sources. Natural GHGs include water vapor (H₂O), or water in a gas form, and is derived from evaporation which forms cloud and rains back on Earth; this is part of the natural water cycle.

Carbon dioxide (CO₂) originates from various natural and human-induced sources. Natural sources include respiration, volcanic eruptions, and oceanic processes. Human activities, such as burning fossil fuels, deforestation, and industrial processes, also significantly contribute to CO₂ emissions.

Methane (CH₄) may come from various sources but mainly cattle and wetlands.

Ozone (O₃), is a gas created up in the atmosphere after a chemical reaction with dioxygen (O₂) and sunlight. The well-known ozone layer helps protect us from harmful UV light coming from the Sun. Finally, Nitrous oxide (N₂O) is a natural part of the Nitrogen cycle and is made up by bacteria, mostly from our oceans.

However, since the industrial revolution, human activities have released huge quantities of these gases in the atmosphere, changing Earth’s natural greenhouse effect and producing global warming.

Moreover, new sources of GHGs have appeared. These potent man-made gases are known as fluorinated gases. They damage the Ozone layer letting more UV light coming through and have a powerful greenhouse effect.

There are four types of anthropogenic GHGs: hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), Sulfur Hexafluoride (SF₆) and Nitrogen Trifluoride (NF₃).

The Tapio tool allows you to estimate the quantity of industrial GHGs emitted by your organization’s activities.

To simplify calculations and comparisons of the various greenhouse gases, their Global Warming Potential (GWP) is measured using a common unit : Carbon Dioxide equivalent (CO₂e). This conversion is done by referring to CO₂, which is the reference gas due to its significant presence in the atmosphere and its substantial impact among greenhouse gases generated by human activities.

Other greenhouse gases are converted into CO₂e by considering their impact and lifespan in the atmosphere relative to those of CO₂.

Taking CO₂ as a reference allows easy conversion and comparison of the impact of these gases in the atmosphere (e.g., CO₂ = 1 CO₂e and CH4 = 28 CO₂e, thus 1kg CH₄ = 28kg CO₂e).

source: AR6 GWP 100y