Skip to main content
Back to Glossary
Definition

Global warming potential (GWP) Definition

Global warming potential (GWP) is the multiplier that converts the mass of methane, nitrous oxide, refrigerants and other non-CO2 greenhouse gases into carbon dioxide equivalent over a stated time horizon.

What is global warming potential?

Global warming potential (GWP) compares one kilogram of a gas with one kilogram of carbon dioxide (CO2) over a chosen period. CO2 has GWP 1. Gas mass x GWP gives carbon dioxide equivalent (CO2e) in the same mass unit. GWP100 compares the cumulative heat-trapping effect of a one-time gas release with the same mass of CO2 over 100 years; it does not state how long the gas remains in the atmosphere or predict a temperature rise.

Intergovernmental Panel on Climate Change (IPCC) assessment reports update GWP values. The GHG Protocol's 2013 amendment requires 100-year IPCC values, recommends the latest report, and says to use one report across scopes, the current year and base year. A 20-year result may be reported separately, not substituted for GWP100.

Why does global warming potential matter to you?

CDP 2026 full corporate Questions 7.6 and 7.7 ask for gross Scope 1 and Scope 2 emissions in metric tons CO2e; they do not ask for a separate GWP field. You meet GWP in the underlying calculation when a refrigerant record is in kilograms or a farm methane estimate is in tonnes of methane (CH4). Keep the gas, unit, horizon, IPCC report and calculation version with your response.

AASB S2 paragraphs B20-B22 require seven gases to be aggregated into metric tonnes CO2e. Paragraphs B21-B22 and AusB22.1 specify the latest 100-year IPCC values and AR6. ESRS E1-6 paragraph AR39(d) requires the most recent IPCC 100-year values for non-CO2 gases. Check the rule named in your reporting instruction before choosing a table.

How is global warming potential calculated?

Use gas mass x GWP = mass of CO2e. A release in kilograms produces kg CO2e; divide by 1,000 for metric tonnes. For a refrigerant blend, use the published blend GWP, not one component's value. Record IPCC AR4, AR5 or AR6 and the 20-year or 100-year horizon.

An emission factor already stated in kg CO2e per litre, kWh or kilometre has already converted any included non-CO2 gases into CO2e. AASB S2 paragraph B22 says not to recalculate a factor already converted to CO2e. Record its key and basis from the public factor ledger. Apply GWP only to a gas mass or result still stated as methane (CH4), nitrous oxide (N2O) or refrigerant.

What mistakes should you avoid?

  • Mixing AR4, AR5 and AR6 values across gases, scopes or the base year without recalculating the affected totals.
  • Applying a GWP again to a factor already expressed in kg CO2e per unit, which counts the conversion twice.
  • Treating GWP as a fuel or electricity emission factor. GWP converts gas mass; an emission factor converts activity data such as litres, kWh or kilometres into emissions.
  • Using a 20-year value where the request specifies GWP100, or omitting the horizon and assessment report from the method note.

Is GWP the same as an emission factor?

No. GWP is a multiplier for gas mass over a stated horizon. An emission factor connects activity to emissions. A refrigerant factor in kg CO2e per kg can equal the blend GWP applied to a release, while a fuel factor per litre also reflects fuel composition and combustion.

Which GWP assessment report should you use?

Use the basis required by the request. GHG Protocol requires 100-year IPCC values and recommends the latest report. AASB S2 AusB22.1 specifies AR6; ESRS E1-6 AR39(d) requires the most recent IPCC values. If an accepted national factor embeds AR5, record that basis and do not relabel it as AR6.

How do you document which GWP values you used?

For each non-CO2 gas, keep the raw mass and unit, GWP value, 20-year or 100-year horizon, IPCC assessment report, source table, calculation version and CO2e result. Attach the source record, such as a refrigerant service report, and the dated GWP or factor file.

Worked example

Suppose a Swedish agricultural cooperative is calculating a customer-requested 2026 inventory, not an ESRS filing. A refrigeration service record confirms that 12 kg of R404A was released from its dairy cold store. The cooperative uses the measured release rather than inferring leakage from an equipment top-up.

The Keslio factors dataset records key refrigerant_r404a_desnz_2026 at 3,943 kg CO2e/kg refrigerant and classifies its geography as Global because GWP is a property of the gas blend, not the release location. The source is the UK DESNZ and DEFRA 2026 Government GHG Conversion Factors for Company Reporting. Methodology section 4.6 calculates this blend factor as 44% HFC-125, 52% HFC-143a and 4% HFC-134a. Section 4.5 says most refrigerant values use 100-year IPCC AR5 GWPs.

Calculation: 12 kg R404A x 3,943 kg CO2e/kg refrigerant = 47,316 kg CO2e. Dividing by 1,000 gives 47 metric tonnes plus 316 kg CO2e. The kg of refrigerant cancels, leaving kg CO2e.

This example uses an AR5-based published blend factor. If the cooperative later reports under ESRS E1-6 paragraph AR39(d), it must use the GWP basis that rule requires rather than relabel this factor as AR6.

Where you'll meet it

CDP 2026 gross global Scope 1 and Scope 2 emissions in metric tons CO2eCDP full corporate Questions 7.6 and 7.7; SME Questions 20.4 and 20.5AASB S2 aggregation of seven gases into CO2e using 100-year GWP valuesAASB S2 paragraphs B20-B22 and AusB22.1ESRS E1-6 conversion of non-CO2 gases using the most recent IPCC 100-year GWP valuesDelegated Regulation (EU) 2023/2772, ESRS E1-6 paragraph AR39(c)-(d)

Related terms

Emission factor

An emission factor converts a measured activity, such as kilowatt-hours of electricity or litres of fuel, into greenhouse gas emissions by stating the emissions released per unit of that activity.

Scope 1 Emissions

Scope 1 emissions are greenhouse gases released directly from sources your company owns or controls, including fuel-burning equipment and vehicles, industrial processes, and refrigerant or other gas leaks.

Carbon Accounting

Carbon accounting is the process of defining a company’s greenhouse gas inventory, collecting activity data, applying emission factors, and reporting Scope 1, Scope 2, and Scope 3 emissions on a consistent basis.

CO2 equivalent (CO2e)

CO2 equivalent (CO2e) expresses different greenhouse gases in one unit by multiplying each gas's mass by its specified 100-year global warming potential, then adding the converted amounts.

Sources

Last verified 2026-08-19

Ready to start?

Tell us what you need.

Bring us the sustainability request, reporting deadline, or strategy question you are facing. We will read it and suggest a practical first step, and the first conversation is free.

Get in touch
Global warming potential (GWP) Definition | Keslio