Glossary›Emissions accounting and measurement›Global warming potential
Glossary term
Cluster D · D22
Tier 1 · differentiator
Global warming potential
Definition
Global warming potential is the factor that converts a quantity of a greenhouse gas into its carbon dioxide equivalent, based on its warming effect relative to carbon dioxide over a defined period, conventionally 100 years. Values are published in IPCC assessment reports and are revised between assessments, so which report’s values apply is a stated part of the measurement basis.
AASB S2 Appendix B
· paragraph AusB22.1 ·
In force
On this page
In practice
This is the term where Australia made a deliberate and useful modification, and it is worth knowing about because the international position is genuinely ambiguous and the Australian one is not.
IFRS S2, and AASB S2 paragraphs B21 and B22 with it, require 100-year global warming potential values from “the latest Intergovernmental Panel on Climate Change assessment available at the reporting date”. That phrasing is a moving reference and it creates a real question: which assessment is available, from what date, and does a supplementary report count.
Appendix B paragraph AusB22.1 closes it. For the purposes of paragraphs B21 and B22, the latest IPCC assessment available at the reporting date means the Panel’s Sixth Assessment Report. Named, fixed, no judgement. The AASB’s reasoning is on the record in its Basis for Conclusions: rather than issue a separate service standard, AASB S2 directly identifies the relevant versions of referenced documents, and the AASB will amend the standard when a later version needs to be referenced. So AR6 stays the answer until the AASB says otherwise, regardless of what the IPCC publishes in the meantime.
The practical consequence for most reporters is smaller than it sounds. Paragraph B22 provides that where an entity’s emission factors have already converted the constituent gases into CO2-e, it is not required to recalculate them using the latest-assessment values. Australian published factor sets arrive in CO2-e. So for an entity using published Australian factors, the AR6 requirement is satisfied at the factor set level and there is no separate calculation to perform.
Where it does bite is in three specific cases.
Case
Why it bites
Direct measurement of gases rather than factors
Rare outside heavy industry, but the paragraph B21 route applies in full and AR6 values must be used.
Supplier-provided or international factors expressed per gas
The factor has not done the CO2-e conversion, so the entity performs it and must do so on AR6.
Refrigerant calculations
Frequently done from gas quantity multiplied by a value looked up from a table, and the table used is often an older assessment carried forward. This is the practical failure. AR6 revised a number of values from AR5, including introducing a distinction between fossil and non-fossil methane for the first time. A refrigerant or methane figure calculated on AR5 values in an AASB S2 disclosure is calculated on the wrong basis.
There is also a jurisdictional carve-out in both B21 and B22: where an entity is required, in whole or in part, by a jurisdictional authority or a listing exchange to use different values, it is permitted to use those values for the part of the entity to which that requirement applies, for as long as it applies. For an Australian NGER reporter that is the relevant limb, and it is another instance of the NGER basis and the AASB S2 basis diverging legitimately.
What the assurer does with it
The assurer asks which assessment report’s values were used and expects the answer to be AR6. Where the entity uses published CO2-e factors, the assurer confirms the factor set states its basis and moves on; this is a documentary check, not a substantive one.
Where gas-level calculations exist (refrigerants being the standard case) they re-perform. They take the quantity of gas, look up the AR6 100-year value, multiply, and compare. A difference points straight to an outdated lookup table.
They accept a stated AR6 basis, or a factor set documented as already CO2-e converted under paragraph B22. They reject an unstated basis, AR5 or AR4 values applied to a current period with no jurisdictional carve-out to justify them, and a mixed basis within one inventory where the refrigerant line uses one assessment and the fuel lines another.
Where an entity invokes the jurisdictional carve-out, the assurer will want the specific requirement identified and the part of the entity it applies to delineated, because the relief is partial by design.
Commonly confused with
Emission factor. A global warming potential converts one gas into CO2-e. An emission factor converts an activity into emissions. Many published factors have a global warming potential already embedded, which is why the two collapse into one another in conversation and why paragraph B22 exists to tell you when you need to care.
Timing and relief
AusB22.1 fixes the reference to AR6. A future IPCC assessment does not flow through automatically; the AASB would have to amend the standard to point at it, and its Basis for Conclusions commits it to doing so as soon as practicable when required. Until that amendment, AR6 is the answer even after a Seventh Assessment Report is published.
Sources
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Review status
Review required
Last reviewed
15 September 2026
Editorial pass, unsigned
Reviewer required
Carbon accounting specialist and registered company auditor
Next scheduled review
1 August 2027
next expected National Greenhouse Accounts Factors release
Part of
Cluster D, Emissions accounting and measurement
49 terms from the head term carbon accounting down to individual Scope 3 categories and the mechanics of factors, boundaries and data quality. The largest cluster in the glossary.
Related terms
The unit the conversion produces
Where the conversion has usually already been applied for you
The Australian factor set that arrives pre-converted
Related questions
Where do Australian emission factors come from?
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The National Greenhouse Accounts Factors, published each year by the Department of Climate Change, Energy, the Environment and Water. They give Scope 1 factors by fuel and Scope 2 electricity factors by state and territory. NGER-registered corporations must use NGER measurement methods for their NGER reporting.
What evidence do we need for each emissions number?
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Every reported number needs a source document you did not create for the report, the activity data drawn from it, the emission factor and its published edition, and the calculation joining them. Fleet fuel needs litres from fuel card statements, electricity needs kWh by site from retailer invoices with the matching state factor, and refrigerants need kilograms by gas type from service records.
Other terms in this cluster
Global warming potential