Global Warming Potential (GWP)

Global Warming Potential (GWP) is a factor that quantifies the relative climate impact of a greenhouse gas compared with carbon dioxide over a given time horizon (20, 100, or 500 years).

The IPCC publishes updated values in its assessment reports; AR6 (2021) sets GWP100 at: CH₄ = 27.9 and N₂O = 273.

Formula

CO₂e = Σ (gas massᵢ × GWPᵢ)

Use in inventories and LCA

• ISO 14064-1 for corporate inventories.
• ISO 14067 and EPDs for products.
• EU CBAM requires AR6 GWP100 values from 2026 onward.

AR6 GWP100 values (main gases)

• CO₂ = 1 (reference).
• CH₄ = 27.9 (fossil), 29.8 (biogenic).
• N₂O = 273.
• SF₆ = 25,200.
• HFC-134a = 1,530.

Advanced considerations

• GWP*: alternative metric reflecting transient warming response.
• GTP (Global Temperature-change Potential).
• GWP20 is relevant for 2030 targets but implies higher values (e.g. CH₄ = 81).

Updating inventories

• Converting from AR5 to AR6 increases CH₄ CO₂e by ~14%.
• ISO recommendation: always declare the GWP version used.
• Sensitivity check: recalculate Net-Zero targets if deviation exceeds 5%.

GWP is the cornerstone of climate accounting. Using the most recent IPCC factors ensures scientific accuracy and alignment with policies such as CBAM and CSRD.