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2027 MR on SLCFs

2027 IPCC Methodology Report on Inventories for Short-lived Climate Forcers

 

Report

The Panel agreed to the outline of the 2027 IPCC Methodology Report on Inventories for Short-lived Climate Forcers at its 61st Session held in in Sofia, Bulgaria from 27 July to 2 August 2024 (Decision IPCC-LXI-7).

The Methodology Report will provide guidance on anthropogenic emissions of Short-lived Climate Forcer at national and annual level, reported in mass units for each individual emitted species. Secondary human-induced substances will not be included.

 

The report aims to cover:

 

  1. All IPCC inventory sectors with categories where the science is assessed to be robust enough to provide guidance for a Tier 1 methodological approach and have a relative contribution to the global/regional emissions of the species, species assessed and potentially covered by the new Methodology Report will be NOX, CO, NMVOCs, SO2, NH3, BC and OC, as well as emissions of primary particulate matter relevant for radiative forcing, as appropriate.

  2. Methane and halogenated species under Montreal Protocol and Kigali Amendment will not be covered since these are already addressed by the existing IPCC Guidelines.

  3. Given the uncertainties in the radiative forcing of H2 and taking note that H2 has not yet been well assessed as a climate forcer by IPCC WGI, H2 emissions relevant for radiative forcing are to be considered by the authors as an Appendix subtitled “Basis for future methodological development” subject to the IPCC’s Principles and Procedures on review and adoption.

  4. For NMVOCs, the methodology should provide estimates for total NMVOCs. The speciation of NMVOCs should be considered by authors, as appropriate.

  5. Anthropogenic emissions only, where anthropogenic refers to emissions from human activities and from managed land.

  6. Sources covered are those of anthropogenic emissions, where scientific evidence is available; while for others, guidance could be provided as a basis for future methodological development.

  7. Geographical and temporal coverage is national and annual level, and authors should also consider guidance on spatial and temporal disaggregation of SLCF emissions.

Around 135 Coordinating Lead Authors and Lead Authors are participating in the writing process, which is scheduled for completion in 2027.

 

The authors were selected by the Task Force Bureau taking into account scientific and technical expertise, geographical and gender balance to the extent possible in line with Appendix A to the Principles Governing IPCC Work.

 

Current Work

 

Following approval of the report outline by the IPCC Panel, the Coordinating Lead Authors and Lead Authors began preparing the report in 2025. Lead Author Meetings provide opportunities for the author teams to coordinate drafting across chapters and volumes, address cross-cutting methodological issues, and advance successive drafts of the report. Three Lead Author Meetings have been held to date, and the Second Order Draft is currently undergoing Government and Expert Review.

 

The report goes through successive stages of expert and government review. Comments received during each review are considered by the authors and used to revise the draft before the next stage. Following the current review, authors will prepare the Final Draft for Government Review before the report is submitted to the IPCC Panel for consideration in 2027.

 

Lead Author Meetings

 

  • LAM1: 24–26 March 2025, Bilbao, Spain — completed
  • LAM2: 7–9 October 2025, Istanbul, Türkiye — completed
  • LAM3: 21–24 April 2026, Rome, Italy — completed
  • LAM4: 8–11 December 2026, Bangkok, Thailand — planned

 

Review Stages

 

  • Expert Review of the First Order Draft: 5 January–27 February 2026 — completed
  • Government and Expert Review of the Second Order Draft: 31 August–25 October 2026 — ongoing
  • Government Review of the Final Draft: 2027 — planned

 

IPCC consideration and publication: 2027 — planned

 

Preparatory Work

 

The decision by the Panel to prepare this Methodology Report was informed by the work of experts at the  scoping meeting held in Brisbane, Australia, from 26 to 28 February 2024.

 

Prior to the scoping meeting, a series of expert meetings was held during the IPCC sixth assessment cycle,   starting with a joint TFI/WGI expert meeting, in July 2018, and including the TFI 1st and 2nd expert meetings (jointly held online) and the third expert meeting  held online in 2021 and 2022 respectively.

 

 

More information

 

 

 

 

 

© 2026 Intergovernmental Panel on Climate Change (IPCC)