Although the GWPs have been updated by the IPCC, estimates of emissions and removals reported under the UNFCCC should continue to use the GWPs from the Second Assessment Report (SAR).

The guidelines for inventory preparation, in the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC/UNEP/OECD/IEA 1997) and the UNFCCC Reporting Guidelines for national inventories were developed and agreed by the COP prior to the publication of the TAR.

Therefore, to comply with international reporting standards under the UNFCCC, official emission estimates are to be reported by Parties using SAR GWP values.