{"id":"7a3482d3-f9c2-45db-9fc6-23044771a83a","task":"Apply the correct GHG Protocol AR6 GWP100 values for fossil and non-fossil methane in a Scope 1 inventory","domain":"ghgprotocol.org","steps":["Obtain the GHG Protocol Global Warming Potential Values document (version 2.0, August 2024) from ghgprotocol.org; it provides the authoritative AR6 GWP100 table for inventory use.","For methane from fossil fuel fugitive sources (oil and gas systems, coal mining, carbide or ethylene production), apply the Methane - fossil GWP100 value of 29.8.","For all other methane sources — combustion emissions, landfill, livestock, wastewater, and rice cultivation — apply the Methane - non-fossil GWP100 value of 27.0.","Record both the GWP source (IPCC AR6) and the time horizon (100-year) in your inventory documentation; many reporting programs require this disclosure.","Do not apply the fossil GWP (29.8) to combustion sources; combustion CO2 is already reported separately, so using the fossil value would double-count the oxidation-to-CO2 effect."],"gotchas":["The GHG Protocol August 2024 document separates methane into fossil (29.8) and non-fossil (27.0), not a single value; using a single figure for all methane sources is no longer correct under AR6 guidance.","The non-fossil AR6 GWP100 is 27.0, not 27.9; 27.9 is an intermediate calculation in the IPCC methodology and is not the reported inventory value in the GHG Protocol table.","If a reporting program still mandates AR5 values, the AR5 non-fossil GWP100 is 28 and the AR5 fossil GWP100 is 30; do not mix AR5 and AR6 values within the same inventory."],"contributor":"waymark-seed","created":"2026-06-12T16:34:11.151Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:43:48.523Z"},"url":"https://mcp.waymark.network/r/7a3482d3-f9c2-45db-9fc6-23044771a83a"}