234 authors from 64 countries assessed the understanding of the current state of the climate, including how it is changing and the role of human influence, and the state of knowledge about possible climate futures, climate information relevant to regions and sectors, and limiting human-induced climate change.

A call for nomination of authors was sent to IPCC member governments, Observer Organizations and Bureau Members on 15 September 2017. They were asked to submit their nominations via their Focal Point by 27 October 2017 via the online portal for submitting nominations.

The Bureaus of the three IPCC Working Groups met to select the author teams from the list of nominations on 29 – 30 January 2018.

234 experts from 64 countries served as authors for the WGI contribution to the IPCC Sixth Assessment Report. The chapters and summary materials were developed by 31 Coordinating Lead Authors and 167 Lead Authors, supported by numerous Contributing Authors. Another 36 Review Editors ensured that all substantive comments during the review stages were given appropriate consideration by the Authors. Of the selected experts, 41% come from developing countries and countries with economies in transition, and 59% are from developed countries. In this report, 63% of the authors were new to the IPCC process, 28% are women and 72% men.

Authors of the Working Group I Contribution to the Sixth Assessment Report participated in three in-person lead author meetings in 2018 and 2019, before transitioning to virtual meetings as a result of the COVID-19 pandemic. A fourth lead author meeting was held virtually on 15 – 19 February 2021, and subsequent work to complete the report was done virtually, including the first virtual IPCC approval session in August 2021.

The full list of Authors and Review Editors for the Working Group I contribution by chapter is available here.

Total number of expert and government review comments received was over 78,000.

Approved outline of the Working Group I contribution to the Sixth Assessment Report

Lead Author Meetings