The Global Warming Potential and Carbon Dioxide Equivalent
Climate change has become one of the most urgent environmental challenges facing humanity. Since the Industrial Revolution in the 19th century, human activities - especially the burning of fossil fuels - have released large amounts of greenhouse gases into the atmosphere. These gases trap heat in the atmosphere, reflecting it back to Earth’s surface. As a result, they disrupt the planet’s natural energy balance and contribute to global warming.
To better understand and measure the impact of different human activities on the climate, experts introduced the concept of Global Warming Potential.
What is Global Warming Potential?
Global Warming Potential (GWP) is a multiplier that shows how much more a specific greenhouse gas contributes to global warming compared to carbon dioxide (CO₂). Carbon dioxide has a GWP of 1, which serves as the reference value. Other greenhouse gases are compared to this baseline.
Here are some examples of greenhouse gases and their GWP values:
| Greenhouse Gas | GWP | Atmospheric Lifetime (years) |
|---|---|---|
| Carbon dioxide (CO₂) | 1 | 100-1,000 |
| Methane (CH₄) | ~28-36 | ~12 |
| Nitrous oxide (N₂O) | ~265-298 | ~114 |
| Fluorinated gases (e.g., HFCs) | ~1,300-12,000+ | up to 50,000 |
As the table shows, even though methane stays in the atmosphere for a much shorter time than carbon dioxide, it has a much stronger warming effect. This means that when we plan how to reduce emissions, we need to consider not only how much gas is emitted, but also how high its GWP is.
Since climate policies aim to reduce not just CO₂ but all greenhouse gases, GWP helps us compare the different gases based on their impact on global warming. It also allows us to calculate something called the carbon dioxide equivalent.
What is Carbon Dioxide Equivalent?
The carbon dioxide equivalent (CO₂e) shows how much a given amount of a greenhouse gas would contribute to global warming if it were CO₂.
It is calculated using this formula:
CO₂e = amount of gas × GWP
Here’s an example:
If a company emits 1 ton of methane (CH₄) per year, and the GWP of methane is between 28 and 36, then this emission equals at least 28 tons of CO₂e:
1 ton CH₄ × 28 = 28 tons CO₂e
The exact GWP of a gas can depend on whether we’re looking at its direct or indirect effects. The more direct the impact, the higher the GWP value.
How is GWP Used in Practice?
Today, GWP plays a major role in most environmental and sustainability calculations. It’s especially important in the following areas:
International Climate Agreements: In the European Union, member states report their greenhouse gas emissions in CO₂e. This ensures transparency and allows fair comparison and accountability when tracking climate targets.
Corporate Carbon Footprinting: Businesses report their emissions in CO₂e in their sustainability reports. This helps them measure and reduce emissions from energy use, transportation, manufacturing, and more.
Comparing Sustainable Investments and Technologies: When comparing technologies like solar panels, batteries, or traditional heating systems, the total greenhouse gas emissions from manufacturing, transport, use, and recycling are expressed in CO₂e. This helps decision-makers choose the most environmentally friendly options.
Life Cycle Assessment (LCA): This method tracks emissions throughout the entire life of a product or service, from raw material extraction through production and use to waste disposal. These emissions are converted into CO₂e using GWP, which supports climate-conscious product development and choices.
Green Public Procurement and Regulation: Many countries and institutions now require CO₂e-based emissions calculations in public tenders. For example, in construction or transport projects. This ensures that taxpayer-funded developments are also environmentally sustainable and that decision-makers consider climate impacts alongside cost and technical details.
Energy Communities and GWP
Energy communities (ECs) are local groups that generate renewable energy, mainly for their own use. Although these communities are often established to enhance energy security and reduce costs, they also offer significant environmental benefits.
Most ECs use solar power systems, which generate electricity without emitting CO₂ during operation. This directly reduces GWP.
Installing a 1 kW solar system can avoid about 0.6 to 0.9 tons of CO₂ emissions per year. A community of 10 households with a shared 10 kW system could save up to 10 tons of CO₂ annually, about the same as the carbon capture of 70 trees in a year.
As we’ve seen, GWP is a key metric in understanding the causes of climate change. It allows us to measure greenhouse gas emissions more accurately, which is essential for achieving the goals of international climate agreements, corporate sustainability strategies, and local green initiatives.
ECs have a significant role to play in reducing GWP. Beyond their direct emissions savings, they set an example and educate others, encouraging both their members and the wider public to adopt more energy-efficient habits and technologies.
