If your carbon calculator uses a GWP-100 value of 25 for methane, it's out of date by one full IPCC assessment cycle. The problem The IPCC Sixth Assessment Report (AR6), published 2021, updated GWP-100 values significantly: Gas AR5 AR6 Change CH4 (fossil) 25 29.8 +19.2% CH4 (biogenic) 25 27.9 +11.6% N2O 265 273 +3.0% SF6 23,500 25,200 +7.2% For a company with significant natural gas combustion, refrigerant leaks, or agricultural emissions, the difference between AR5 and AR6 is not cosmetic. It's a ~19% understatement of methane-related emissions. Why it hasn't been fixed widely The GHG Protocol Corporate Standard permits either AR5 or AR6. Most tools defaulted to AR5 when they launched and haven't updated. Many sustainability teams don't know which GWP basis their tools use — it's rarely displayed prominently.…