The IPCC is currently in its Sixth Assessment cycle. During this cycle, the Panel will produce three Special Reports, a Methodology Report on national greenhouse gas inventories and the Sixth Assessment Report (AR6). More information on the Sixth Assessment cycle is available here.
 
The meeting to draft the outline of the Sixth Assessment Report (AR6) took place in Addis Ababa (Ethiopia) from 1 to 5 May 2017. The draft outlines were approved by the Panel when it met in early September 2017. The three Working Group contributions to AR6 will be finalized in 2021 and the AR6 Synthesis Report in the first half of 2022 in time for the first UNFCCC global stocktake under the Paris Agreement in 2023
 
Approved outlines of the Working Group contributions to the Sixth Assessment Report:

Working Group I - The Physical Science Basis
Working Group II - Impacts, Adaptation, and Vulnerability
Working Group III - Mitigation of Climate Change

Quick Links

Climate Change 2013: The Physical Science Basis Climate Change 2014: Impacts, Adaptation and Vulnerability Climate Change 2014: Mitigation of Climate Change Climate Change 2014: Synthesis Report All AR5 Volumes AR5 Outreach Calendar AR5 leaflet AR5 Authors List Key AR5 Dates AR5 Reference Document AR5 SYR Scope and Outline Cut-off dates for literature Working Group AR5 and SYR sites: Working Group I Working Group II Working Group III Synthesis Report

The Fifth Assessment Report (AR5) is the most comprehensive assessment of scientific knowledge on climate change since 2007 when the Fourth Assessment Report (AR4) was released. It was released in four parts between September 2013 and November 2014.   AR5 is made up of the full reports prepared by theWorking Groups (I, II and III) and their Summaries for Policymakers as well as the Synthesis Report.   Click here for the WGI contribution on the physical science basis of climate change; here for the WGII contribution on impacts, adaptation and vulnerability; and here for the WGIII contribution on mitigation of climate change. The Synthesis Report can be found here.

This page covers the contents of the AR5, the process of developing the AR5 and the wide participation of experts in the AR5 writing and review process.
 

   AR5 Contents

AR5 puts greater emphasis on assessing the socio-economic aspects of climate change and its implications for sustainable development.
 
Some new features of AR5 as a whole include:

A new set of scenarios for analysis across Working Group contributions;

Dedicated chapters on sea level change, carbon cycle and climate phenomena such as monsoons and El Niño;

Much greater regional detail on climate change impacts, adaptation and mitigation interactions; inter- and intra-regional impacts; and a multi-sector synthesis;

Risk management and the framing of a response (both adaptation and mitigation), including scientific information relevant to Article 2 of the UNFCCC referring to the "...stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system".

 

The outlines and contents of the AR5 Working Group reports, approved by the Panel at its 31st Session in Bali, Indonesia, can be found in the AR5 reference document. See the AR5 leaflet for abbreviated outlines of each volume of the report.
Note: Changes in the Working Group III outline, as reflected in the following progress reports, were considered and approved by the Panel at its 34th and 35th Sessions (IPCC-XXXV/Doc. 21, IPCC-XXXIV/Doc. 18, Rev.1).
 

Several cross-cutting themes and methodologies meriting consistent treatment across Working Groups were identified for AR5. The IPCC organized expert meetings and workshops to facilitate consideration of complex topics relevant to the AR5 assessment process.
 

Key AR5 cross-cutting themes are:
 

• Water and the Earth System: Changes, Impacts and Responses;
• Carbon Cycle including Ocean Acidification (see Meeting Report);
• Ice Sheets and Sea-Level Rise (see Meeting Report);
• Mitigation, Adaptation and Sustainable Development; and
• Article 2 of the UNFCCC (see UNFCCC for definition).

 

Key AR5 cross-cutting methodologies are:
 

• Consistent Evaluation of Uncertainties and Risks (see Guidance Note);
• Costing and Economic Analysis (see Meeting Report);
• Regional Aspects;
• Treatment of Scenarios (see Meeting Report);
• Greenhouse Gas Metrics (see Meeting Report).

 
The AR5 Synthesis Report - The Synthesis Report synthesizes and integrates material contained within the Working Group reports and Special Reports. It is written in a non-technical style suitable for policymakers and addresses a broad range of policy-relevant but policy-neutral questions.
 
The AR5 Synthesis Report (SYR) was prepared by a Core Writing Team (CWT) led by the IPCC Chair. The team consisted of authors of the three Working Group report-writing teams and members of the Executive Committee.
 
See AR5 Synthesis Report website for further details.

  The Decision to Prepare a Fifth Assessment Report

The decision to Prepare a Fifth Assessment Report (AR5) was taken by members of the IPCC (the Panel) at its 28th Session in Budapest, Hungary (9-10 April 2008).

  The AR5 Scoping Process

A scoping meeting was then held in Venice, Italy (13-17 July 2009), to develop the scope and outline of the Fifth Assessment Report.
 
Working Group contributions to AR5
 
The outlines of the Working Group contributions were approved at the 31st Session of the IPCC in Bali, Indonesia (26-29 October 2009). The outlines, concept notes on cross-cutting matters, as well as workshops and expert meetings to be held in support of the AR5 assessment process, are compiled in the AR5 reference document.
 
Synthesis Report

On 25-27 August 2010, a scoping meeting for the AR5 Synthesis Report was held in Liege, Belgium, to develop its outline and scope. At its 32nd Session in Busan, Republic of Korea (11-14 October 2010), the Panel agreed on the scope and outline for the AR5 Synthesis Report (SYR).

  AR5 Expert Meetings and Workshops

A number of expert meetings and workshops, including on cross-cutting issues, were held to support the process of preparing the AR5 as outlined in the AR5 Reference document. Reports of these meetings are published as IPCC Supporting Material. For details on the meetings that have been held see AR5 Workshops and Expert Meetings.

  Approval/Acceptance of Working Group SPMs and Full Reports

The IPCC considered the WGI contribution to AR5 on the physical science basis in Stockholm, Sweden on 23-26 September 2013, the WGII contribution on impacts, adaptation and vulnerability on 25-29 March 2014 in Yokohama, Japan, WGIII contribution on mitigation of climate change on 7-11 April 2014 in Berlin, Germany and the Synthesis Report on 27 October - 1 November 2014 in Copenhagen, Denmark. The Working Group sessions approved their respective SPMs and accepted their respective full reports. A brief IPCC plenary session followed to accept the action taken by each Working Group. The Panel approved the SPM of the Synthesis report and adopted the longer report.

  The AR5 Writing and Review Process

IPCC reports are prepared by experts selected by the Bureau, based on nominations by governments and observer organizations, to serve as IPCC Lead Authors. Over 830 authors worked on AR5, which encompasses over 50 chapters. The AR5 was prepared according to Appendix A to the Principles Governing IPCC Work on Procedures for the Preparation, Review, Acceptance, Adoption, Approval and Publication of IPCC Reports.  On the right is a schematic description of the process.
 

The diagram illustrates the process for preparing reports of the IPCC. The process for the Synthesis Report is slightly different (see below).
 
Review is an essential part of the IPCC process to ensure an objective, unbiased, transparent and comprehensive assessment of current scientific technical information. Both expert reviewers and governments are called upon to comment on scientific and technical matters in a review process of several stages for a given IPCC report.
 
For more information on the preparation of IPCC reports see Principles and Procedures page.
 

  The full review process for AR5 involved:

Note: Observer organizations have the opportunity of involving their experts in expert review stages. Such experts provide reviews under their own name; they do not represent these observer organizations.

Number of review comments on Fifth Assessment Report

Note: some experts register for more than one Working Group.

AR5 Calendar and Schedule

  Full AR5 Schedule

A comprehensive overview schedule that contains dates for AR5 Scoping Meetings, Sessions of the Panel to approve outlines of the reports, Lead Author meetings, review periods and cut-off dates for new literature assessed in the AR5 is available here (AR5 Key Dates).
 
For all IPCC meetings and review periods, please see the IPCC Calendar.
 

  Literature Cut-Off Dates

The IPCC process assesses published literature; it does not involve carrying out research. For inclusion in the Second Order Draft (SOD) of a Working Group contribution, literature must be submitted for peer review prior to the finalization of the SOD. In order to be reflected in the AR5, literature must be accepted for publication before the final draft is finalized. Any reference that does not fulfill these criteria was removed from the draft contribution together with the statement(s) that it supports.
 
Working Groups provided the following cut-off dates for new literature.
 

  AR5 Lead Authors and Review Editors

About 830 Authors and Review Editors from over 80 countries were selected for the IPCC's Fifth Assessment Report (AR5) from about 3,600 nominated individuals. In the course of the assessment process Lead Authors enlisted Contributing Authors to prepare technical information in the form of text, graphs or data for assimilation by the Lead Authors into the draft sections. See the complete list of Authors and Review Editors, and the following statistics and regional coverage.
 

 AR5 Author Teams

Authors of the AR5 Synthesis Report

The IPCC Chair led the Synthesis Report's Core Writing Team, whose composition was agreed by the 45th Session of the IPCC Bureau, Geneva, 13-14 March 2012.

   Lead Author Meetings

In the course of the assessment process, four Lead Author meetings are held by each Working Group. All Coordinating Lead Authors and Lead Authors get together to initiate the writing process, consult on cross-cutting issues, consider review comments received and revise the text accordingly. Review Editors participate in such meetings to ensure that all review comments are afforded appropriate consideration.  
 

Working Group I

WGI First Lead Author Meeting 8-11 November 2010 Kunming (China)	WGI Third Lead Author Meeting 16-20 April 2012 Marrakech (Morocco)
WGI Second Lead Author Meeting 18-22 July 2011 Brest (France)	WGI Fourth Lead Author Meeting 13-19 January 2013 Hobart (Australia)

  
More information on the WGI contribution to AR5 can be found on the WGI AR5 website.

Working Group II

WGII First Lead Author Meeting 11-14 January 2011 Tsukuba (Japan)	WGII Third Lead Author Meeting 23-26 October 2012 Buenos Aires (Argentina)
WGII Second Lead Author Meeting 12-15 December 2011 San Francisco, CA (USA)	WGII Fourth Lead Author Meeting 15-19 July 2013 Bled (Slovenia)

  
More information on the WGII contribution to AR5 can be found on the WGII AR5 website.

Working Group III

WGIII First Lead Author Meeting 12-15 July 2011 Changwon City (Republic of Korea)	WGIII Third Lead Author Meeting 5-9 November 2012 Vigo (Spain)
See Photo gallery	See Photo gallery of Working Group III AR5 Authors
WGIII Second Lead Author Meeting 19-23 March 2012 Wellington (New Zealand)	WGIII Fourth Lead Author Meeting 1-5 July 2013 Addis Ababa (Ethiopia)
	(Photo courtesy Benjamin Kriemann/IPCC)

 
More information on the WGIII contribution to AR5 can be found on the WGIII AR5 website.

Synthesis Report

SYR Core Writing Team (CWT) Meetings already held:

CWT-1 Meeting 11-13 June 2012 Geneva (Switzerland)	CWT-2 Meeting 10-12 June 2013 Oslo (Norway)
	Photo ©VisitOSLO/Nancy Bundt
CWT-3 Meeting 7-10 January 2014 De Bilt (The Netherlands)	CWT-3-bis Meeting 13-14 April 2014 Berlin (Germany)
	Photo: the Estrel Convention Centre
CWT-4 Meeting 30 June - 3 July 2014 Kuala Lumpur (Malaysia)	CWT-5 Meeting 24-25 October 2014 Copenhagen (Denmark)
Photo of Putrajaya, Malaysia

 
More information on the Synthesis Report can be found on the AR5 Synthesis Report website.

  The Development of Scenarios for the AR5

In the AR5 process, particular attention was given to the treatment of scenarios. See the 2007 Meeting Report and the 2010 Meeting Report (Berlin) on Socio-Economic Scenarios.

When the Panel decided in 2008 to prepare a Fifth Assessment Report, the Panel also invited the scientific community developing new scenarios for the analysis of emissions, climate change, impacts, and response strategies to move forward actively for the timely delivery of scenario results to feed the assessment process.

In the past, the IPCC coordinated the process of developing scenarios for its assessments. During its 25th session (Mauritius, 26-28 April 2006), the IPCC decided that rather than directly coordinating and approving new scenarios itself, the process of scenario development should now be coordinated by the research community.
 
The IPCC sought to "catalyze" the timely production by others of new scenarios for the Fifth Assessment Report (AR5). To this end an expert meeting was held from 19-21 September 2007 in Noordwijkerhout, the Netherlands (Meeting Report) which considered the plans by the scientific community and agreed representative concentration pathways.
 
For more information on this process conducted by the scientific community, see the IPCC's new scenarios webpage.

In addition to Assessment Reports, the IPCC publishes Special Reports on specific topics. The preparation and approval process for all IPCC Special Reports follows the same procedures as for IPCC Assessment Reports.
 
The IPCC has produced Special Reports on various topics such as aviation; regional impacts of climate change; technology transfer; emissions scenarios; land use, land-use change and forestry; carbon dioxide capture and storage; and the relationship between safeguarding the ozone layer and the global climate system. For more information on these see the Special Reports section of the Publications page.
 
Special Reports in the Sixth Assessment cycle
During the 43rd Session of the IPCC (Nairobi, Kenya, 11 – 13 April 2016), the Panel decided to produce three Special Reports during the Sixth Assessment Report (AR6) cycle.

It decided to accept the invitation from the UNFCCC to prepare Global Warming of 1.5ºC, an IPCC special report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. For more information including, timeline, documentation and other relevant links click here. It will be finalized in early October 2018.

The Panel also decided to prepare two other Special Reports requested by governments: Special Report on the Ocean and Cryosphere in a Changing Climate; and Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. These will be finalized by September 2019.
 
Two IPCC Special Reports in 2011

In 2011, two IPCC Special Reports were finalized; the Special Report on Renewable Energy Sources and Climate Change Mitigation (SRREN) and the Special Report on Managing Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX). Both Special Reports were requested by governments.
 

Special Report on Renewable Energy Sources and Climate Change Mitigation (SRREN)
 

The Special Report on Renewable Energy Sources and Climate Change Mitigation (SRREN) was approved and accepted at the 11th Session of Working Group III that took place on 5-8 May 2011 in Abu Dhabi, United Arab Emirates.

This report assesses existing literature on the future potential of renewable energy for the mitigation of climate change. It covers the six most important renewable energy technologies, as well as their integration into present and future energy systems. It also takes into consideration the environmental and social consequences associated with these technologies, the cost, and strategies to overcome technical as well as non-technical obstacles to their application and diffusion.

More than 130 authors and 100 contributing authors from all over the world contributed to the preparation of SRREN on a voluntary basis.

• Summary for Policymakers (SPM) released on 9 May 2011
• Press Release
• Generic Presentation
• Videos
• Information Note
• Full Report

Additional information on the report can be found here.
 

Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX)
 

The Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) was approved and accepted at the first Joint Session of IPCC Working Groups I and II that met on 14-17 November 2011 in Kampala, Uganda. 
 
The report assesses the effect that climate change has on the threat of natural disasters and how nations can better manage an expected change in the frequency of occurrence and intensity of severe weather patterns. It aims to be a resource for decision-makers to prepare more effectively for managing the risks of these events. A potentially important area for consideration is also the detection of trends in extreme events and the attribution of these trends to human influence.
 
More than 80 authors, 19 review editors, and more than 100 contributing authors from all over the world contributed to the preparation of SREX. The United Nations International Strategy for Disaster Reduction prepared the original proposal for the report.  

• Summary for Policymakers (SPM) released on 18 November 2011
• Press Release
• Generic Presentation
• Videos
• Fact Sheet
• Full Report
• SREX Press Conference [recording]
  

 

Additional information on the report can be found here.

Since 1992, the IPCC has been preparing methodologies and guidelines to assist Parties to the United Nations Framework Convention on Climate Change (UNFCCC) and its Kyoto Protocol to prepare national inventories of greenhouse gas emissions by sources and removals by sinks. The last major publication was the 2006 IPCC Guidelines for National Greenhouse Gas Inventories.
 
At the 43rd Session of the IPCC in April 2016, the Panel agreed to refine the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, including producing a Methodology Report in order to update and supplement the 2006 IPCC Guidelines. Work on the Guidelines is necessary to update and provide a sound scientific basis for future international climate action especially under the Paris Agreement. This process will result in a Methodology Report which will be used in conjunction with the 2006 IPCC Guidelines.
 
In October 2013, the IPCC accepted two new Methodology Reports prepared by its Task Force on National Greenhouse Gas Inventories (TFI); the 2013 Supplement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories: Wetlands (Wetlands Supplement) and the 2013 Revised Supplementary Methods and Good Practice Guidance arising from the Kyoto Protocol (KP Supplement).
 
At its 33rd session, the IPCC decided to produce additional guidance – the Wetlands Supplement – to cover inland wetlands such as peatlands, draining and rewetting of organic soils, and coastal wetlands such as mangroves. This was requested by the UNFCCC, and the IPCC hopes that the 2013 supplementary guidance will make an important contribution to future international action on wetlands. More information about the Wetlands Supplement can be found here.
 
At the invitation of the Parties to the Kyoto Protocol to the UNFCCC, and following agreement by the IPCC at its 35th Session, the TFI completed the KP Supplement. This supplement is a review and an update of the good practice guidance on estimating greenhouse gas emissions and removals from land use, land-use change and forestry (LULUCF) under the Kyoto Protocol. More information about the KP Supplement can be found here
 
The TFI has also produced IPCC Inventory Software. It is available free on CD or can be downloaded here. The TFI also produces other material to assist users of the guidelines, such as the Emissions Factor Database (EFDB).
 
For more information on the TFI please see the website.

Scenarios of potential future anthropogenic climate change, the underlying driving forces, and the response options are an important component of IPCC work. In the past the IPCC coordinated the process of developing scenarios for its assessments (see AR 1990, SR 1994 and SRES 2000). In 2006 the IPCC decided that rather than directly coordinating and approving scenarios, the process of scenario development should be coordinated by the scientific community. The IPCC would catalyze the timely production of new scenarios for possible use in its Fifth Assessment Report (AR5). To this end an expert meeting was held on 19-21 September 2007 in Noorwijkerhout, the Netherlands (Report of the meeting) which considered the plans by the scientific community and agreed representative concentration pathways. The meeting was attended by experts on integrated assessment (IAM), impacts; adaptation and vulnerability research (IAV); and climate modelling (CM).
 
Representative Concentration Pathways (RCPs), which were used in AR5 facilitated coordination of new integrated socioeconomic, emissions, and climate scenarios. The main rationale for beginning with RCPs was to expedite the development of a broad literature of ntegrated scenarios by allowing the modeling of climate system responses to human activities to proceed in parallel to emissions scenario development.
 
After the conclusion of AR5, the research community and the IPCC reflected on the new scenario process and how it can be further improved to allow for a more integrated assessment of mitigation, adaptation and climate change impacts and broader sustainable development across the entirety of IPCC work in the future. In this regard, an expert meeting on scenarios was held in Laxenburg, Austria on 18-20 May 2015 (Report of the Meeting).
 
The research community has developed Shared Socioeconomic Pathways (SSPs), consisting of a set of narratives and corresponding quantitative information describing how global socioeconomic issues could develop in the 21st century. The narratives were developed by a large team of experts and provide a ‘storyline’, describing how important trends such as resource availability, technical development, and lifestyle changes evolve, whilst the quantitative information translates these storylines into gridded projections of potential future population, GDP, and urbanization until 2100.
 
More information on scenario development and coordination with the scientific community can be found in the Progress Report submitted to the 32nd Session of the Panel, Busan, Republic of Korea, 11 - 14 October 2010 (IPCC-XXXII/Doc. 16). This report discusses the Draft Memorandum of Understanding between the Integrated Assessment Modeling Consortium (IAMC) and IPCC Working Groups II and III (IPCC-XXXII/INF.10), and the link between the IPCC and the scientific community on the scenario development process which continues now through the Co-Chairs of the Working Groups.
 
In this regard, a joint IPCC workshop of Working Groups II and III on "Socioeconomic Scenarios for Climate Change Impact and Response Assessments" was held in Berlin, Germary on 1-3 November 2010. For background and supporting material for this workshop, please see here.
 
Finally, the IPCC's Task Group on Data and Scenario Support for Impact and Climate Analysis (TGICA) also provides via the Data Distribution Centre (DDC) a set of web pages that provide an overview of processes for developing scenarios to support climate change research. These pages are intended for researchers who may wish to participate in scenario development, who use scenarios in their research, or who wish to learn more about current efforts to improve the coordination of different fields of climate research.