IPCC Process

The Working Group I contribution to the IPCC Fifth Assessment Report (WGI AR5) Climate Change 2013: The Physical Science Basis was prepared following the IPCC Principles and Procedures, as outlined in the graphic.

IPCC Working Group Session

Stages of Report

IPCC Panel Initiates Assessment Report The IPCC Panel decides whether to prepare an IPCC Assessment Report, including the overall structure and the scientific areas to be considered by each Working Group. The outline of the Report is developed through a scoping process involving climate change experts from all relevant disciplines and users of IPCC reports, including representatives from governments. The scoping meeting to define the outline of the AR5 was held in Venice, Italy, 13-17 July 2009.

The outline and structure of the contribution of each Working Group to an Assessment Report is developed by the Working Group Bureau in consultation with experts, governments and observer organisations. The outlines of the Working Group contributions to AR5 were approved by the 31st Session of the IPCC meeting in Bali, Indonesia, 26-29 October 2009, together with a revised timetable.
IPCC Panel Initiates Assessment Report
Publication Before publication, Coordinating Lead Authors and Lead Authors address any changes to the text in the underlying chapters arising from approved changes to the Summary for Policymakers. Most IPCC Reports are published commercially. A limited number of free copies may be provided to experts from developing countries and countries with economies in transition. At the time of publication, the First Order and Second Order Drafts of the Report, their review comments, and the associated responses to the comments are made publicly available, usually by posting on the relevant IPCC website(s). Publication Governments Nominate Experts as Authors and Review Editors Governments and observer organizations are invited to nominate experts who can serve as Coordinating Lead Authors (CLA), Lead Authors (LA), and Review Editors (RE) for the Report. For WGI AR5, there were over 1000 nominations from 63 countries. Governments Nominate Experts as Authors and Review Editors Accepts Report At the Working Group Session the SPM is approved and the underlying Report is accepted. The Report is then provided to the Panel for acceptance. Accepts Report Approves SPM Line-by-Line A Session of the Working Group(s) is convened to approve the Summary for Policymakers line-by-line. For WGI AR5 this took place in Stockholm, Sweden, 23-26 September 2013. Approves SPM Line-by-Line WG Bureau Selects Authors and Review Editors Coordinating Lead Authors, Lead Authors, and Review Editors are selected by the relevant Working Group(s) Bureau from the nominations received. Further experts can be invited by the WG Bureau to fill gaps in expertise. Selection of Coordinating Lead Authors, Lead Authors, and Review Editors reflects the requirements for appropriate expertise; a balance of disciplines; and geographic and gender balance, including ensuring representation of experts from developed and developing countries and countries with economies in transition as well as ensuring involvement of those who have not been involved with IPCC before.
A total of 258 Lead Authors and Review Editors from 44 countries were selected for WGI AR5. Nominees not selected as authors or Review Editors are invited to be Expert Reviewers of the Report.
WG Bureau Selects Authors and Review Editors
Final Goverment Distribution The Final Draft of the Report is distributed prior to a Session of the relevant Working Group(s) inviting governments to submit additional comments on the Final Draft of the Summary for Policymakers. There were 1,855 written comments on the Final Draft of the WGI AR5 Summary for Policymakers from 32 governments. Final Goverment Distribution Authors Prepare First Order Draft The writing process is normally initiated by a meeting of all Coordinating Lead Authors and Lead Authors (Lead Author meeting). At this meeting, a more detailed structure is developed for the Report and tasks are allocated to chapter team members. The writing process starts and the First Order Draft is finalised shortly after the second Lead Author meeting.
The WGI AR5 First Lead Author Meeting was held in Kunming, China, from 08 to 11 November 2010, and the Second Lead Author Meeting was held in Brest, France, from 18 to 22 July 2011.
Authors Prepare First Order Draft
Authors Prepare Second Order Draft Authors prepare the Second Order Draft, taking into consideration all comments received and documenting how each comment was handled. Review Editors ensure that all comments are appropriately considered, that there is a recorded answer for each comment, and that accepted comments are reflected in the text. Authors Prepare Second Order Draft Authors Prepare Final Draft After taking into account the comments from the Expert and Government Review, Coordinating Lead Authors and Lead Authors are responsible, along with Review Editors, for writing the Final Draft of the Report. It is important that Reports describe different (possibly controversial) scientific, technical, and socioeconomic views on a subject, particularly if they are relevant to the policy debate. The Final Draft of the Summary for Policymakers is drafted. Authors Prepare Final Draft Authors Prepare SPM First Order Draft The First Order Draft of the Summary for Policymakers is drafted. The Summary for Policymakers provides a policy relevant and policy neutral synthesis of the key findings of the Report. Authors Prepare SPM First Order Draft Authors Prepare SPM Final Draft A Session of the Working Group approves (line-by-line) the Summary for Policymakers, which is consistent with the factual material contained in the full scientific, technical, and socioeconomic content of the Assessment Report. Prior to the Session, all government comments that were submitted in advance are considered by the SPM drafting team in preparing proposals for revision of the Final Draft SPM to be considered by the Working Group Session. Coordinating Lead Authors are present at the Session to ensure consistency between the underlying Report and the Summary for Policymakers. Authors Prepare SPM Final Draft Authors Revise SPM Final Draft A Session of the Working Group approves (line-by-line) the Summary for Policymakers, which is consistent with the factual material contained in the full scientific, technical, and socioeconomic content of the Special Report. Coordinating Lead Authors provide technical assistance to ensure consistency between the underlying Report and the Summary for Policymakers. Authors Revise SPM Final Draft Expert Review The First Order Draft is circulated to experts with significant expertise and/or publications in particular areas of the Report, and experts nominated by governments and observer organizations. The experts comment on the accuracy and completeness of the scientific/technical/socioeconomic content as well as on the overall balance of the Report. The comments are collected by the Technical Support Unit and discussed at the Third Lead Author Meeting, which was held from 16 to 20 April 2012 in Marrakech, Morocco. There were 21,400 comments on the WGI AR5 First Order Draft from 659 Expert Reviewers. Expert Review Expert & Government Review The Second Order Draft of the Report and the First Order Draft of the Summary for Policymakers are distributed to Expert Reviewers and the governments of the 195 member countries of the IPCC. The comments are collected by the Technical Support Unit and discussed at the Fourth Lead Author Meeting, which was held from 13 to 19 January 2013 in Hobart, Tasmania, Australia. There were 31,422 comments on the WGI AR5 Second Order Draft from 800 Expert Reviewers and 26 Governments. Expert & Government Review Government SPM Review The Final Draft of the Report is distributed prior to a Session of the relevant Working Group(s) inviting governments to submit additional comments on the Final Draft of the Summary for Policymakers. There were 1,855 written comments on the Final Draft of the WGI AR5 Summary for Policymakers from 32 governments. Government SPM Review

Press / Media Contact

IPCC Working Group I
Pauline Midgley
Director of Communication and International Relations
Zähringerstrasse 25
3012 Bern

Phone: +41 31 631 5620
Fax: +41 31 631 5615
Email: media@ipcc.unibe.ch