Climate Change 2021: The Physical Science Basis

The Working Group I contribution to the Sixth Assessment Report is the most up-to-date physical understanding of the climate system and climate change, bringing together the latest advances in climate science, and combining multiple lines of evidence from paleoclimate, observations, process understanding, and global and regional climate simulations.

Report

The IPCC has finalized the first part of the Sixth Assessment Report, Climate Change 2021: The Physical Science Basis, the Working Group I contribution to the Sixth Assessment Report. It was finalized on 6 August 2021 during the 14th Session of Working Group I and 54th Session of the IPCC.

Read the report here

Disclaimer: The Technical Summary (TS), the full Report Chapters, the Annexes and the Supplementary Materials are the Final Government Distribution versions, and remain subject to revisions following the SPM approval, corrigenda, copy-editing, and layout.

Download the report by chapter, annexes and Supplementary materials 

Background

The Sixth Assessment Report consists of contributions from each of the three IPCC Working Groups and a Synthesis Report (SYR), which integrates the Working Group contributions and the Special Reports produced in the cycle.

The meeting to draft the outline of the Sixth Assessment Report took place in Addis Ababa (Ethiopia) in May 2017. The draft outlines were approved by the 46th Session of the Panel in September 2017. The approved outline for the working group I contribution is here

The First Order Draft of the Working Group I contribution to AR6 underwent an expert review (29 April – 23 June 2019).

The Second Order Draft was reviewed by governments and experts from 2 March 2020. It was initially scheduled to end on 26 April, but closed on 5 June.

Between 4 May to 20 June 2021, the final draft of the Working Group I contribution was circulated to governments for comment on the Summary for Policymakers in preparation for the 14th Session of Working Group I and 54th Session of the IPCC.

Authors and Review Editors

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

Lead Author Meetings

Review and Scoping

Information on the review process and the scoping process that preceded it is available here.

Multimedia

Report video:

Report video trailer:

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