> For the complete documentation index, see [llms.txt](https://kb.bravegen.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kb.bravegen.com/carbon/configuration/reporting-settings/gwp-values.md).

# GWP Values

Review and edit the statement describing which global warming potential basis your emissions calculations use.

Global warming potential (GWP) is the factor that converts each greenhouse gas into a common unit — carbon dioxide equivalent, `tCO₂e`. Every emissions figure BraveGen Carbon produces depends on a GWP basis, and the basis is set by the emission factors you use rather than by a switch in the product.

The **GWP Values** setting holds a plain-language statement describing which basis applies where. It is a disclosure, not a calculation control: editing the statement does not change any calculated figure.

***

### Why the basis matters

GWP values are published by the IPCC and revised with each assessment report — AR4, AR5, and AR6 are the ones in current use. The values differ between reports, so the same activity data produces different `tCO₂e` totals depending on which report the factor is based on. Methane is the clearest example: its 100-year GWP rose across successive assessment reports, so a methane-heavy inventory restated on a newer basis moves noticeably.

Reporting frameworks and programmes each expect a particular basis, and they do not all expect the same one. Disclosing the basis you used — and being able to show it per factor — is what lets a reader compare your figures with anyone else's.

***

### How BraveGen Carbon applies GWP

BraveGen Carbon may use multiple [Emission Factor Libraries](/carbon/core-concepts/emission-factors/emission-factor-libraries.md) in a single inventory — supplier-specific, jurisdictional, and spend-based datasets side by side. GWP is resolved per calculation, in this order:

1. **Factor-level metadata.** Where a factor records its own GWP basis, that basis is used.
2. **Library or framework default.** Where a factor does not specify a basis, the default associated with its library or reporting framework applies.

Factor-level metadata always takes precedence over the library default. That matters for libraries containing mixed GWP bases or annual updates, where a blanket library-level assumption would be wrong for some factors.

Where a single calculation combines factors from more than one library, each factor contributes on its own GWP basis, and the result is preserved with the calculation record so the figure can be reproduced and audited later.

The default statement records the following library defaults, applied only where a factor does not state its own basis:

| Library                       | Default GWP basis                                                    |
| ----------------------------- | -------------------------------------------------------------------- |
| MfE                           | AR4                                                                  |
| EXIOBASE                      | AR6                                                                  |
| NGA / NGER                    | AR5                                                                  |
| DEFRA / UK government factors | The basis specified in the relevant release year and factor metadata |

***

### Review the statement

Only Administrators can edit the statement. See [User Roles](/carbon/configuration/user-management/user-roles.md).

Go to **Settings → Carbon Configuration → Reporting**. The **GWP Values** row shows **View Statement** — select the edit icon to open the dialog.

| Field     | Description                                                                                                               |
| --------- | ------------------------------------------------------------------------------------------------------------------------- |
| Statement | The disclosure text describing the GWP basis your calculations use. Minimum 40 characters. Disclosed in your audit trail. |

BraveGen Carbon ships a default statement that describes the behaviour above and is accurate for a standard configuration. Most organisations can leave it as it is.

Select **Save Changes** to apply an edited statement, or **Cancel** to discard it. **Reset to Default** restores the shipped wording — use it if an edit has drifted out of line with how your factors are actually configured.

{% hint style="info" %}
Editing the statement changes what you disclose, not what you calculate. If the statement and your factor configuration disagree, the factors are right and the statement needs correcting.
{% endhint %}

***

### When to edit it

Edit the statement when your circumstances make the default incomplete or inaccurate:

* You use [Custom Emission Factors](/carbon/core-concepts/emission-factors/custom-emission-factors.md) whose GWP basis is not covered by the default wording.
* A programme you report under requires a specific basis, and you want that requirement stated.
* You have restated historical figures onto a different basis and need the change described.
* Your assurer has asked for wording that addresses a particular aspect of your inventory.

Write it for an external auditor or verifier. The statement is included in your [audit trail snapshots](/carbon/audit-trail/snapshots.md) and read alongside your other disclosures.

***

### Activity Log

Every change to the statement is recorded in the **Activity Log** on the dialog, with the user, the timestamp, and the text supplied at the time. Users can reply to an entry to add context, and pin an entry to keep it at the top.

Because the statement is a disclosure that should track your factor configuration, the log is what shows a reviewer when the wording was last confirmed as accurate.

***

### Frequently asked questions

<details>

<summary>Does changing the statement recalculate my emissions?</summary>

No. GWP is applied by the emission factor at calculation time. The statement describes what happened; it does not drive it.

</details>

<details>

<summary>Can I force the whole inventory onto one assessment report?</summary>

Not from this setting. The basis comes from the factors themselves, so moving to a single basis means using factor libraries built on that basis. See [Emission Factor Libraries](/carbon/core-concepts/emission-factors/emission-factor-libraries.md).

</details>

<details>

<summary>Is it a problem that my inventory mixes AR4, AR5, and AR6?</summary>

It is common, because different jurisdictions update on different cycles. What matters is that the mix is disclosed and that each figure is reproducible — which is why the GWP basis is preserved with the calculation record. Check whether any programme you report under requires a single basis.

</details>

<details>

<summary>Does a change of GWP basis trigger a base year recalculation?</summary>

It can. A change of GWP basis is a methodology change, so assess it against your [Base Year Recalculation Policy](/carbon/configuration/reporting-settings/base-year/base-year-recalculation-policy.md) like any other.

</details>

<details>

<summary>What does Reset to Default do?</summary>

It restores the statement BraveGen ships. Any edits you have made are replaced, so copy anything you want to keep before selecting it.

</details>

***

### Key points

* GWP converts each greenhouse gas into `tCO₂e`, and the values differ between IPCC assessment reports.
* The basis comes from the emission factor, not from a setting — factor-level metadata beats the library default.
* Calculations combining libraries use each factor's own basis, preserved with the calculation record.
* The statement is a disclosure included in your audit trail. Keep it aligned with how your factors are configured.
* Reset to Default restores the shipped wording.