Global Warming Potential (GWP)

This article explains the relevance and application of the Global Warming Potential (GWP). Given the advancing climate change due to the increase in greenhouse gases (GHG) in the atmosphere, understanding the climate impacts of these gases is essential for effective measures to reduce GHG emissions. The article addresses the most important GHG and their GWP, as determined by the Intergovernmental Panel on Climate Change (IPCC). Additionally, a detailed list of GWPs from IPCC reports is provided for download below.

Global Warming Potential (GWP)

The Global Warming Potential (GWP) is a metric for assessing the warming potential of greenhouse gases and their impact on climate change compared to the reference gas carbon dioxide (CO₂) [1]. Using GWPs, the climate effects of different greenhouse gases (GHGs) can be made comparable, as this metric allows for conversion into carbon dioxide equivalents (CO₂e). The comparability of GHGs through GWP is relevant for all climate-related issues, indicating compliance with the goals of the Kyoto Protocol and associated GHG reductions in CO₂e [2]. Additionally, it is relevant for companies due to legal reporting obligations, as they must determine product- or company-specific carbon footprints in CO₂e. Due to varying in the atmospheric lifetime of gases, the considered time frame is also relevant for GWP and is determined for periods of 20, 100, and 500 years. GWP values are commonly used with a time horizon of 100 years (GWP₁₀₀), where a higher GWP indicates a stronger climate impact per unit of greenhouse gas [1].

For example, methane (CH₄) has a GWP₁₀₀ value of 28 t CO₂e/ t methane. This means over a 100-year period, one ton of emitted methane is 28 times more climate-damaging than one ton of CO₂, consequently accelerating climate change to a greater extent [2].

What are the most relevant greenhouse gases?

Greenhouse gases (GHGs) are gaseous components of the atmosphere, both from natural and anthropogenic emission sources. They absorb and emit radiation at specific wavelengths within the spectrum of terrestrial radiation emitted by the Earth’s surface, the atmosphere itself, and clouds. This causes the greenhouse effect [3].

Figure 1 provides an overview of the greenhouse gases described in the Kyoto Protocol. The Kyoto Protocol identifies some of the major contributors to greenhouse gas emissions, including carbon dioxide (CO₂), nitrous oxide (N₂O), methane (CH₄), as well as fluorinated greenhouse gases such as hydrogen-containing fluorinated hydrocarbons (HFCs), perfluorinated hydrocarbons (PFCs), and sulfur hexafluoride (SF₆) [1, 4, 5]. Since 2015, nitrogen trifluoride (NF₃) has also been included. In Germany, for example, in 2020, 87.1% of emitted greenhouse gases consisted of CO₂, 6.5% of CH₄, 4.6% of N₂O, and approximately 1.7% of F-gases. The contribution of NF₃ was negligible [2]. Besides the mentioned greenhouse gases, there are other gases like hydrogen (H₂) that can have indirect greenhouse effects, but they are not listed here.

How is the GWP determined?

GWP values are calculated, determined, and regularly updated by international scientific bodies and organizations. A key authority in this field is the IPCC, a globally recognized scientific organization that analyzes climate change and its impacts on behalf of the United Nations. The IPCC produces reports and guidelines in which GWP values for different time frames, along with the methods for calculation and updating, are detailed. New scientific insights lead to adjustments in GWP values, which are then updated in various IPCC Assessment Reports (AR), the second one known as Second Assessment Reports (SAR). Figure 2 illustrates the development of GWP₁₀₀ values for greenhouse gas emissions of CO₂, CH₄, and N₂O over the different publication years of the IPCC [1].

Figure 2: Evolution of GWP₁₀₀ values for selected greenhouse gas emissions across various publication years of the IPCC (own illustration based on [3, 6–8])

A detailed list of GWP₁₀₀ values from the Fifth and Sixth Assessment Reports of the IPCC, including key Kyoto gases, is available for download below.

More Information

• Info Article: What is the Corporate Sustainability Reporting Directive (CSRD)?
• Info Article: What is the Sustainable Finance Disclosure Regulation (SFDR)?
• Series of Articles on Methods of Sustainability Assessment: Life Cycle Assessment
• Series of Articles on Methods of Sustainability Assessment: „Scopes 1 – 3“ in Corporate Evaluation
• The FfE Monitoring Report 2022 – Emission Balancing of the FfE (German version)

Literature

[1] J. Gacs, “Das Global Warming Potential (GWP) | Bedeutung und Anwendung”, Green Vision Solutions GmbH, 13. Okt. 2023, 2023. [Online]. Verfügbar unter: https://greenvisionsolutions.de/global-warming-potential-gwp/. Zugriff am: 13. Dezember 2023.

[2] Umweltbundesamt, Die Treibhausgase. [Online]. Verfügbar unter: https://www.umweltbundesamt.de/themen/klima-energie/klimaschutz-energiepolitik-in-deutschland/treibhausgas-emissionen/die-treibhausgase (Zugriff am: 13. Dezember 2023).

[3] IPCC, “Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change”, 2013. [Online]. Verfügbar unter: https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_sar_wg_I_full_report.pdf.

[4] IPCC, “IPCC Fifth Assessment Report – Climate Change 2013: The Physical Science Basis Chapter 8 – Anthropogenic and Natural Radiative Forcing”, 2013. [Online]. Verfügbar unter: https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter08_FINAL.pdf. Zugriff am: 13. November 2023.

[5] United Nations, “Kyoto Protocol to the United Nations Framework Convention on Climate Change”, 1998. [Online]. Verfügbar unter: https://unfccc.int/resource/docs/convkp/kpeng.pdf.

[6] IPCC, “Climate Change 1995: The Science of Climate Change”, 1995. [Online]. Verfügbar unter: https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_sar_wg_I_full_report.pdf

[7] IPCC, “Climate Change 2007: The Physical Science Basis.: Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change” [Online]. Verfügbar unter: https://www.ipcc.ch/site/assets/uploads/2018/05/ar4_wg1_full_report-1.pdf.

[8] IPCC, “Climate Change 2021: The Physical Science Basis.: Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change”, 2021.