Charles Dubouix
Climate Change (2/3): The three main Greenhouse gases The Usual Suspects
- There are different GHGs, including Carbon Dioxide (CO2), Methane, and Nitrous Oxide, each with its own atmospheric lifetime and global warming potential.
- In general, CO2 represents 2/3 of the GHGs in the atmosphere, which is why the effect of other greenhouse gases is typically measured in CO2 equivalent (tCO2e).
- In the transport industry, CO2 is responsible for almost all of the greenhouse effect (methane and nitrous oxide are very low in the sector)
Definition
As previously mentioned, a greenhouse gas is a gas that partially blocks infrared radiation emitted from the Earth's surface. This process traps heat on the ground, leading to the greenhouse effect.
The different types of Greenhouse Gases: the usual suspects
There are several types of greenhouse gases, but the three main ones are:
- Carbon Dioxide (CO2)
- Methane (CH4)
- Nitrous Oxide (N2O)
Where do they come from?
CO2 is the most well-known greenhouse gas and is responsible for the majority of greenhouse gas emissions. It is mainly emitted during the combustion of fossil fuels and changes in land use, such as deforestation.
Methane emissions come from agriculture, particularly from ruminant livestock, rice cultivation, and managed manure. Methane is also emitted from the production and transport of fossil fuels, particularly from methane leakages.
Nitrous oxide emissions come from agriculture, particularly from the use of nitrogen fertilizers, and from the burning of fossil fuels.
Global Warming Potential
Not all greenhouse gases have the same impact on the environment
The comparison between greenhouse gases depends on their lifespan and heat absorption. This comparison is done using the Global Warming Potential (GWP) indicator, which measures the heat absorbed by a given mass of gas over a specific period.
A single metric measure
To compare greenhouse gas emissions based on their Global Warming Potential, we use the term carbon dioxide equivalent or CO2 equivalent (CO2-eq). As CO2 makes up two-thirds of all GHGs in the atmosphere, other gases are converted to an equivalent amount of carbon dioxide with the same global warming potential. For instance, emitting 1 ton of methane has the same impact on climate, during the 100 first years, as emitting about 28 tons of CO2.
Overall, understanding greenhouse gases and their impact on the environment is crucial for addressing climate change and promoting sustainable development.
| GHG | Source | Lifespan in the atmosphere | GWP 100 |
|---|---|---|---|
CO2 (Carbon dioxide) | - Fossil fuels - Deforestation | 100 years | 1 |
CH4 (Methane) | - Livestock (cows, for example) - Rice fields - Fossil fuels | 12 years | 25 |
N2O (Nitrogen Protoxyde) | - Fertilizers - Some chemicals processes | 120 years | 298 |
