Since the IPCC was created in 1988, there have been 6 Synthesis Reports:

• The Overview of the First Assessment Report (1990)
• The IPCC Second Assessment Report Synthesis of Scientific-technical Information Relevant to Interpreting Article 2 of the UNFCCC (1995)
• The Synthesis Report of the Third Assessment Report (2001)
• The Synthesis Report of the Fourth Assessment Report (2007)
• The Synthesis Report of the Fifth Assessment Report (2014)
• The Synthesis Report of the Sixth Assessment Report (2023) 

The AR6 Synthesis Report is based on the three Working Group contributions to the Sixth Assessment Report as well as on the three Special Reports prepared in the sixth assessment cycle.  

To support the Synthesis Report writing process, the Synthesis Report Technical Support Unit organizes various meetings including Core Writing Team meetings. The Core Writing Team is the group of authors who prepare the Synthesis Report. The  Core Writing Team is selected by the Bureau from the author teams of the three IPCC Working Groups and the Special Reports prepared in a cycle. The Core Writing Team should reflect a balance in geographical distribution, gender, and representative of a range of expertise. The CWT also includes  the Chair, the IPCC Vice-Chairs, the Working Group Co-Chairs, the heads of the Working Group and Synthesis Report Technical Support Units, and the Secretary of the IPCC. The list of 30 Core Writing Team authors and 9 Review Editors of AR6 Synthesis Report the can be found here. 

The IPCC Chair is responsible for the preparation of the Synthesis Report.

A Technical Support Unit may be established to support the IPCC Chair in preparing the Synthesis Report of an Assessment Report.