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While carbon dioxide (CO2) is often the face of climate change, other gases – such as methane (CH4) and nitrous oxide (N2O) – also contribute and can be far more potent in their impact. “Global Warming Potentials” (GWPs) serve as a crucial tool for the measurement and tracking of such impact, helping scientists, policymakers and businesses make informed decisions on the reduction of emissions across industries and substances.
Greenhouse gases (GHGs) are responsible for warming the planet by slowing down the rate at which energy is released from the atmosphere. GWP measures the impact of these gases more effectively by not only accounting for the general amount of emissions (in tons), but also their ability to absorb energy (“radiative efficiency”) and how they persist in the atmosphere over time. It uses time-based structures (usually 20, 100 or 500 years – identified by GWP20, GWP100 and GWP500, respectively) and results are expressed in Carbon Dioxide Equivalence (CO2e) to enable comparisons across different gases. These values will vary depending on the methodology used for calculation (e.g. AR4, AR5), any values used in this article are purely for explanatory purposes, always check the methodology relevant for specific needs.
GHGs can vary significantly in their ability to trap heat. Thus, GWP uses a multivariate framework (by factoring aforementioned radiative efficiency, general amount and time frame) to function as a unified unit of measurement, allowing for emissions to be estimated as a whole, facilitating comparisons, calculations, and decision-making.
CO2 is used as the baseline, with a GWP of 1, regardless of the timeframe measured. Because it remains in the atmosphere for thousands of years, carbon dioxide emissions can increase concentrations in the atmosphere for thousands of years. The predominance of CO2 allows for easy comparisons amongst other less prevalent gases.
Other notable examples include:
Methane (CH4), with an estimated GWP100 of around 27 to 30. CH4 usually lasts about a decade in the atmosphere (10-12 years). Despite its a short lifespan, it has a much greater heat-trapping capacity than CO2. As a result, its GWP20 is much higher (~80-85). However, after that period most of the methane will have disappeared, leaving only residual effects of the CO2 it converted into, thus accounting for its lower GWP100. Nitrous Oxide (N2O) has a GWP100 of approximately 273, and remains in the atmosphere for about a century, making it a relatively high-impact and long-lasting pollutant.
Certain synthetic gases are often classified as high-GWP gases, these include substances such as hydrofluorocarbons (HFCs), Chlorofluorocarbons (CFCs), Hydrochlorofluorocarbons (HCFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), all of which have GWP values up in the thousands of even tens of thousands.
On the other hand, some gases have a GWP value equal to or even lower than CO2. Ammonia, used in refrigeration and agriculture, has a GWP(X) of 0 (as per the ISCC's AR4 methodology) and breaks down in the atmosphere rather quickly. Other hydrocarbons, like propane (C3H8) and butane (C4H10), usually used as fuel and refrigerants, also have a GWP well below 1 (GWP100 of 0.02 and 0.006, respectively), making them much less impactful than CO2.
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Since there are many GHGs, and their effects on the climate vary greatly, GWP serves as a valuable tool for understanding and comparing their impacts. It allows for a standardized comparison by expressing their warming effects in terms of carbon dioxide equivalents (CO2e) over specific time frames. This improves consistency in climate policies, emissions accounting and overall climate change mitigation strategies.
Many international climate regulations and agreements use GWP in their structure for emission reduction targets and guidelines, with frameworks such as the Kyoto Protocol and the Paris Agreement using GWP to set legally binding reduction goals. The UK, for example, was bound to reduce its overall GHG emissions by 12,5% below its 1990 levels, requiring emissions for gases like methane to be converted into CO2e using the, at the time established by the IPCC, GWP100 of approximately 21. In compliance-based markets, such as the EU Emissions Trading System (EU ETS), CO2e is used in calculations based on GWP to determine emission allowances and carbon credit valuations.
The understanding and application of GWP is essential for businesses who wish to, or must, calculate their carbon footprint, set emission reduction goals, and ensure transparent sustainability reporting. Standards like the Greenhouse Gas Protocol or Science-Based Targets Initiative (SBTi) use ‘Global Warming Potentials’ as an indispensable metric to guide companies in reporting of high-GWP emissions across Scopes 1, 2, and 3.
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The combustion created by jet fuels is responsible for the release of CO2 in high levels, N2O and other short-lived pollutants, contributing significantly to greenhouse effect warming. This puts increasing pressure on the industry to adhere to and comply with global climate targets and reduce their emissions. Many companies have started adopting and investing in Sustainable Aviation Fuels (SAF), with substantially lower life cycle GWPs and impact than conventional jet fuels. Furthermore, carbon offset programs based on these metrics, like CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation), incentivize companies to perform carbon accounting and work on moving closer to net-zero emissions. These work with reputable schemes such as ISCC, which OTC Flow is a part of to offer sustainable alternatives to help companies decarbonize their aviation operations.
With traditional vehicle fuels being accountable for approximately 20% of global GHG emissions (CO2, N2O, CH4), the transition to electric vehicles (EVs) and low-GWP biofuels is becoming more prevalent in the industry. Until the EV industry is able to source its electricity largely from green sources, alternatives such as bioLNG and biomethane, a renewable fuel produced from organic waste and that has a much lower GWP than fossil fuels, are increasingly used in heavy transport operation, as well as in several other applications that assist in lowering the carbon footprint of companies and governmental agencies.
It’s clear that reducing the use of high-GWP chemicals is vital in mitigating climate change. Solutions include enforcing stronger legislation like the Montreal Protocol, and switching to low-GWP alternatives such as ammonia, bioLNG, hydrocarbons, and CO2-based refrigeration. Additionally, improving energy efficiency in cooling and industrial processes can reduce reliance on harmful substances.
At OTC Flow, we help businesses transition to low-GWP solutions through renewable gas, carbon offset programs, and energy efficiency certificates, ensuring they meet sustainability goals while remaining compliant with evolving regulations. By integrating these strategies, industries can take meaningful action to reduce emissions and drive a greener future.