IPCC authors convene in Mexico City on carbon removal accounting rules
More than 120 authors working under the Intergovernmental Panel on Climate Change have gathered in Mexico City to advance the First Order Draft of the 2027 Methodology Report on Carbon Dioxide Removal Technologies, Carbon Capture, Utilization and Storage, the document that will set how countries account for these technologies in national greenhouse gas inventories.
The meeting runs from 11 to 14 August, hosted by the National Autonomous University of Mexico with support from the Government of Mexico. It is the second Lead Author Meeting for the report and follows an initial gathering in Rome in April, held at the headquarters of the Food and Agriculture Organization, where drafting began with more than 150 experts in attendance. Authors in Mexico City will develop the draft further and consolidate it into a single First Order Draft.
The report is being prepared by the IPCC’s Task Force on National Greenhouse Gas Inventories and is scheduled for release in 2027. Its scope spans direct air capture, soil and biomass-based removals, coastal ecosystem approaches, carbon capture, utilisation and long-term storage, and the production of durable materials derived from captured carbon dioxide. Transport, injection and sequestration of carbon dioxide in connection with enhanced oil, gas and coalbed methane recovery also fall within its coverage.
Mazhar Hayat, Co-Chair of the Task Force, said consistent, reliable and transparent greenhouse gas inventories are essential for informed climate policymaking, and that as removal and capture approaches expand the report will provide up-to-date methods grounded in current scientific and technical knowledge. Fellow Co-Chair Takeshi Enoki has described the report as a fundamental reference for transparent and consistent reporting on climate action.
The structure follows the format of the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, comprising an overview chapter and six volumes, a deliberate choice intended to allow inventory compilers to use the new report alongside the existing guidelines rather than as a separate system.
Member governments agreed the scientific content at the Panel’s 63rd Plenary Session in Lima in October 2025 under decision IPCC-LXIII-6. The decision was informed by a scoping meeting in Copenhagen in October 2024 and an expert meeting in Vienna in July 2024, both of which used the removal methods identified in the AR6 Working Group III report as their starting point while noting that several such activities are already covered by existing guidelines. Author nominations were invited from national focal points by December 2025.
The First Order Draft is expected to be completed by October, with Expert Review anticipated to open later this year and running through to October 2026 according to Task Force planning documents. All registered experts will have an opportunity to participate.
The methodological stakes are considerable for carbon markets. National inventory accounting determines how removals are recognised under the Paris Agreement, which in turn shapes how host countries treat corresponding adjustments for internationally transferred credits and how removals are counted toward nationally determined contributions. The absence of agreed inventory methods for newer pathways such as enhanced weathering, biochar and marine approaches has been a recurring obstacle for governments considering whether and how to integrate them into compliance frameworks, including the EU’s carbon removal certification framework and its proposed pathway for bringing permanent removals into the emissions trading system.
Separately, the Task Force reports that Expert Review of the First Order Draft of the Methodology Report on Short-Lived Climate Forcers concluded in February, with Government and Expert Review of the Second Order Draft beginning in September. All three Working Groups are progressing First Order Drafts for Expert Review, and approval sessions for two methodology reports are scheduled for the second half of 2027.
