Intergovernmental Panel on Climate Change

The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations responsible for advancing knowledge on human-induced climate change.^[1] It was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), and later endorsed by the United Nations General Assembly.^[2] It is based in Geneva, Switzerland, and is composed of 195 member states.^[3] The IPCC is governed by its member states, which elect a bureau of scientists to serve for the duration of an assessment cycle (usually six to seven years); the bureau selects experts nominated by governments and observer organisations to prepare IPCC reports.^[4] The IPCC is supported by a secretariat and various "Technical Support Units" from specialised working groups and task forces.^[4]

The IPCC provides objective and comprehensive scientific information on anthropogenic climate change, including the natural, political, and economic impacts and risks, and possible response options. It does not conduct original research nor monitor climate change, but rather undertakes a periodic, systematic review of all relevant published literature.^[5] Thousands of scientists and other experts volunteer to review the data and compile key findings into "Assessment Reports" for policymakers and the general public;^[6] this has been described as the biggest peer review process in the scientific community.^[7]

The IPCC is an internationally accepted authority on climate change, and its work is widely agreed upon by leading climate scientists as well as governments.^[8][7] Its reports play a key role in the United Nations Framework Convention on Climate Change (UNFCCC),^{[9] [10]} with the Fifth Assessment Report heavily informing the landmark Paris Agreement in 2015.^[11] The IPCC shared the 2007 Nobel Peace Prize with Al Gore for contributions to the human understanding of climate change.^[12]

In 2015, the IPCC began its sixth assessment cycle, to be completed in 2023. In August 2021, the IPCC published its Working Group I contribution to the Sixth Assessment Report (IPCC AR6) on the physical science basis of climate change,^[13] which The Guardian described as the "starkest warning yet" of "major inevitable and irreversible climate changes",^[14] a theme echoed by many newspapers around the world.^[15] On 28 February 2022, the IPCC released its Working Group II report on impacts and adaptation.^[16] Working Group III's "mitigation of climate change" contribution to the Sixth Assessment was made available on 4 April 2022.^[17] The Sixth Assessment Report is due to be completed with a Synthesis Report in March 2023.

During this period of the Sixth Assessment Report, the IPCC has released three special reports: the Special Report on Global Warming of 1.5 °C in 2018, and the Special Report on Climate Change and Land (SRCCL), and the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC), both in 2019. It also updated its methodologies in 2019. Consequently, the sixth assessment cycle has been described as the most ambitious in the IPCC's history.^[18]

Origins and aims[edit | edit source]

The IPCC developed from an international scientific body, the Advisory Group on Greenhouse Gases^[19] set up in 1986 by the International Council of Scientific Unions, the United Nations Environment Programme (UNEP), and the World Meteorological Organization (WMO) to review scientific research on greenhouse gases and assess increases in greenhouse gases and their impacts. This small group of scientists lacked the resources to cover the increasingly complex interdisciplinary nature of climate science. The United States government sought an international convention for restrictions on greenhouse gases, and under the conservative Reagan Administration expressed concern about unrestrained influence from independent scientists or from United Nations bodies such as UNEP and the WMO. The U.S. government was the main force in shaping the IPCC as an autonomous intergovernmental body with the participation of scientists as both experts and official representatives of their governments, which would produce reports backed by all leading relevant scientists, and which then had to gain consensus agreement from every participating government. In this way, the IPCC was formed as a hybrid between a scientific body and an intergovernmental political organization.^[20]

The United Nations formally endorsed the creation of the IPCC in 1988, citing the fact that "[c]ertain human activities could change global climate patterns, threatening present and future generations with potentially severe economic and social consequences", and that "[c]ontinued growth in atmospheric concentrations of 'greenhouse' gases could produce global warming with an eventual rise in sea levels, the effects of which could be disastrous for mankind if timely steps are not taken at all levels".^[2] To that end, the IPCC was tasked with reviewing peer-reviewed scientific literature and other relevant publications to provide information on the state of knowledge about climate change and its consequences and impacts.

Organization[edit | edit source]

The IPCC does not conduct original research, but produces comprehensive assessments, reports on special topics, and methodologies to help countries estimate their emissions and removals through sinks of greenhouse gases. Its assessments build on previous reports and scientific publications, highlighting the trajectory towards the latest knowledge; for example, the wording of the reports from the first to the sixth assessment reflects the growing evidence for a changing climate caused by human activity.

The IPCC has adopted and published "Principles Governing IPCC Work", which states that the IPCC will assess:^[10]

• the risk of human-induced climate change,
• its potential impacts, and
• possible options for prevention.

The IPCC conducts its assessments on a "comprehensive, objective, open and transparent basis" that encompasses all "scientific, technical and socioeconomic information relevant to understanding the scientific basis" of climate change. IPCC reports must be neutral with respect to policy recommendations, but may address the objective scientific, technical and socioeconomic factors relevant to enacting certain policies.^[10]

The IPCC is chaired by Korean economist Hoesung Lee, who has served since 8 October 2015 with the election of the new IPCC Bureau,^[21] along with three vice-chairs, Youba Sokona [fr] (Mali), Ko Barrett (USA) and Thelma Krug (Brazil).^[22] Before this election, the IPCC was led by Vice-Chair Ismail El Gizouli, who was designated acting chair after the resignation of Rajendra K. Pachauri in February 2015.^[23] The previous chairs were Rajendra K. Pachauri, elected in 2002; Robert Watson in 1997; and Bert Bolin in 1988.^[24]

The Panel itself is composed of representatives appointed by governments who take part in plenary sessions of the IPCC and its Working Groups. Participation of delegates with appropriate expertise is encouraged. Non-governmental and intergovernmental organizations may attend as observers.^[25] Sessions of the Panel, IPCC Bureau, workshops, expert and lead authors meetings are by invitation only.^[10] About 500 people from 130 countries attended the 48th Session of the Panel in Incheon, Republic of Korea, in October 2018, including 290 government officials and 60 representatives of observer organizations. The opening ceremonies of sessions of the Panel and of Lead Author Meetings are open to media, but otherwise IPCC meetings are closed.

The IPCC is structured as follows:

• IPCC Panel: Meets in plenary session about twice a year (more for approval of reports).^[4] It controls the organization's structure, procedures, work programme and budget, and accepts and approves IPCC reports. The Panel is the IPCC corporate entity.^[6]
• Chair: Elected by the Panel. Chairs the Bureau and other bodies and represents the organization externally.
• Secretariat: Administers activities, supports the Chair and Bureau, point of contact for governments. Supported by UNEP and the WMO.
• Bureau: Elected by the Panel. Its 34 members include IPCC Vice-Chairs, Co-Chairs of Working Groups and the Task Force, and Vice-Chairs of the Working Groups.^[26] It provides guidance to the Panel on the scientific and technical aspects of its work.^[27]
• Working Groups: Each has two Co-Chairs, one from the developed and one from developing world, and a technical support unit. Sessions of the Working Group approve the Summary for Policymakers of special reports and working group contributions to an assessment report. Each Working Group has a Bureau comprising its Co-Chairs and Vice-Chairs, who are also members of the IPCC Bureau.
  • Working Group I: Assesses scientific aspects of the climate system and climate change. Co-Chairs: Valérie Masson-Delmotte and Panmao Zhai^[26]
  • Working Group II: Assesses vulnerability of socioeconomic and natural systems to climate change, consequences, and adaptation options. Co-Chairs: Hans-Otto Pörtner and Debra Roberts^[26]
  • Working Group III: Assesses options for limiting greenhouse gas emissions and otherwise mitigating climate change. Co-Chairs: Priyadarshi R. Shukla and Jim Skea^[26]
• Task Force on National Greenhouse Gas Inventories.^[28] Co-Chairs: Kiyoto Tanabe and Eduardo Calvo Buendía
  • Task Force Bureau: Comprises the two Co-Chairs, who are also members of the IPCC Bureau, and 12 members.
• Executive Committee: Comprises the Chair, IPCC Vice-Chairs and the Co-Chairs of the Working Groups and Task Force. Its role includes addressing urgent issues that arise between sessions of the Panel.^[29]

Funding[edit | edit source]

The IPCC receives funding through a dedicated trust fund, established in 1989 by UNEP and the WMO. The trust fund receives annual cash contributions by the WMO, UNEP, and IPCC member governments; payments are voluntary and there is no set amount required. Administrative and operational costs, such as for the secretariat and headquarters, are provided by the WMO, which also sets the IPCC's financial regulations and rules.^[30] The Panel sets the annual budget.

List of all reports[edit | edit source]

Assessment reports[edit | edit source]

The IPCC has published five comprehensive assessment reports and is completing the sixth, reviewing the latest climate science, as well as a number of special reports on particular topics.^[31] These reports are prepared by teams of relevant researchers selected by the Bureau from government nominations. Expert reviewers from a wide range of governments, IPCC observers and other organizations are invited at different stages to comment on various aspects of the drafts.^[32]

The IPCC published its First Assessment Report (FAR) in 1990. Its most recent assessment report is the Sixth Assessment Report (AR6), whose first three instalments were released in 2021 to 2022, with the final synthesis report due in March 2023. Each assessment report consists of a contribution form each of the three working groups, plus a synthesis report that integrates the working group contributions and any special reports produced in that assessment cycle.

The IPCC does not carry out its own research nor does it monitor climate related data. Its reports assess scientific papers and independently documented results from other scientific bodies. Therefore, its schedule for producing reports requires a deadline for consideration of publications prior to the report's finalization. In principle, this means that any significant new evidence or events that change our understanding of climate science between this deadline and publication of an IPCC report cannot be included. However, there is a steady evolution of key findings and levels of scientific confidence from one assessment report to the next.^[33] Each subsequent IPCC report notes areas where the science has improved since the previous report and also notes areas where further research is required.

Scope and preparation of the reports[edit | edit source]

Lead authors of IPCC reports assess the available information about climate change based on published sources.^[5][34] According to IPCC guidelines, authors should give priority to peer-reviewed sources.^[5] Authors may refer to non-peer-reviewed sources ("grey literature"), provided that they are of sufficient quality.^[5] Examples of non-peer-reviewed sources include model results, reports from government agencies and non-governmental organizations, and industry journals.^[5]

Authors prepare drafts of a full report divided into chapters, a technical summary of this report, and a summary for policymakers. ^[5]

There are generally three stages in the review process:^[5] Expert review, government/expert review and government review of: summaries for policymakers, overview chapters and the synthesis report. Review comments are in an open archive for at least five years.The report is completed at sessions of the responsible working group and panel, where government representatives review the Summary for Policymakers in dialogue with the authors who have drafted it.

There are several types of endorsement which documents receive:

• Approval - Material has been subjected to detailed, line by line discussion and agreement (Working Group Summaries for Policymakers are approved by their Working Groups, the Synthesis Report Summary for Policymakers is approved by the Panel).
• Adoption - Endorsed section by section (and not line by line) (the Panel adopts Overview Chapters of Methodology Reports and the IPCC Synthesis Report).
• Acceptance - Not been subject to line by line discussion and agreement, but presents a comprehensive, objective, and balanced view of the subject matter (Working Groups accept their reports, Task Force Reports are accepted by the Panel, Working Group Summaries for Policymakers are accepted by the Panel after working group approval).

Authors[edit | edit source]

Each chapter has a number of authors who are responsible for writing and editing the material. A chapter typically has two "coordinating lead authors", ten to fifteen "lead authors", and a somewhat larger number of "contributing authors". The coordinating lead authors are responsible for assembling the contributions of the other authors, ensuring that they meet stylistic and formatting requirements, and reporting to the Working Group chairs. Lead authors are responsible for writing sections of chapters. Contributing authors prepare text, graphs or data for inclusion by the lead authors.^[35]

The choice of authors by the Bureau aims for a range of views, expertise and geographical representation, ensuring representation of experts from developing and developed countries and countries with economies in transition. The Bureau also seeks a balance between male and female authors and a balance between those who have worked previously on IPCC reports and those new to the process.

Scientists who participate in the IPCC assessment process do so without any compensation other than the normal salaries they receive from their home institutions. The process is labour-intensive, diverting time and resources from participating scientists' research programs.^[36] Concerns have been raised that the large uncompensated time commitment and disruption to their own research may discourage qualified scientists from participating.^[37]

First assessment report (1990)[edit | edit source]

Second assessment report (1995)[edit | edit source]

Third assessment report (2001)[edit | edit source]

Fourth assessment report (2007)[edit | edit source]

Fifth assessment report (2014)[edit | edit source]

Sixth assessment report (2021/2022)[edit | edit source]

Other reports[edit | edit source]

Special reports[edit | edit source]

In addition to comprehensive assessments of climate change, the IPCC publishes Special Reports on specific topics proposed by governments or observer organizations. The preparation and approval process for all IPCC Special Reports follows the same procedures as for IPCC Assessment Reports. Details of recent examples follow.

Special Report on Emissions Scenarios (SRES)[edit | edit source]

The Special Report on Emissions Scenarios (SRES) is a report by the IPCC which was published in 2000.^[51] The SRES contains "scenarios" of future changes in emissions of greenhouse gases and sulphur dioxide.^[52] One of the uses of the SRES scenarios is to project future changes in climate, e.g., changes in global mean temperature. The SRES scenarios were used in the IPCC's Third^[53] and Fourth Assessment Reports.^[54]

The SRES scenarios are "baseline" (or "reference") scenarios, which means that they do not take into account any current or future measures to limit greenhouse gas (GHG) emissions (e.g., the Kyoto Protocol to the United Nations Framework Convention on Climate Change).^[55] SRES emissions projections are broadly comparable in range to the baseline projections that have been developed by the scientific community.^[56]

Special report on Renewable Energy Sources and Climate Change Mitigation (SRREN)[edit | edit source]

This report assesses existing literature on renewable energy commercialisation for the mitigation of climate change.^[57] It was approved in 2011 and covers the six most important renewable energy technologies in a transition, 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 from all over the world contributed to the preparation of report on a voluntary basis – not to mention more than 100 scientists, who served as contributing authors.

Special Report on managing the risks of extreme events and disasters to advance climate change adaptation (SREX)[edit | edit source]

The report was approved in 2011.^[58] It 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 become 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 this report.

Special Report on Global Warming of 1.5 °C (SR15)[edit | edit source]

Special Report on Climate Change and Land (SRCCL)[edit | edit source]

Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC)[edit | edit source]

Methodology Reports[edit | edit source]

Within the IPCC the National Greenhouse Gas Inventory Programme develops methodologies to estimate emissions and removals of greenhouse gases.^[71] Originally undertaken by IPCC Working Group I in collaboration with the Organization for Economic Co-operation and Development and the International Energy Agency, the programme has been managed since 1998 by the IPCC's Task Force on National Greenhouse Gas Inventories (TFI) ^[72] whose Technical Support Unit is hosted by Japan's Institute for Global Environment Strategies . The objectives of the National Greenhouse Gas Inventory Programme are:

• to develop and refine an internationally agreed methodology and software for the calculation and reporting of national greenhouse gas emissions and removals; and
• to encourage the widespread use of this methodology by countries participating in the IPCC and by signatories of the UNFCCC.

The IPCC has started preparations for a methodology report on short-lived climate forcers to be completed in the seventh assessment cycle.

Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories[edit | edit source]

The 1996 Guidelines for National Greenhouse Gas Inventories provide the methodological basis for the estimation of national greenhouse gas emissions inventories.^[73] Over time these guidelines have been completed with good practice reports: Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories and Good Practice Guidance for Land Use, Land-Use Change and Forestry.

The 1996 guidelines and the two good practice reports are to be used by parties to the UNFCCC and to the Kyoto Protocol in their annual submissions of national greenhouse gas inventories.

2006 IPCC Guidelines for National Greenhouse Gas Inventories[edit | edit source]

The 2006 IPCC Guidelines for National Greenhouse Gas Inventories is an update to these emission estimation methodologies, including a large number of default emission factors (a factor estimating the amount of emissions for an activity).^[74] The IPCC prepared this new version of the guidelines on request of the parties to the UNFCCC,^[75] and the methods were officially accepted for use in national greenhouse gas emissions reporting under the UNFCCC and the Kyoto Protocol at the 2013 United Nations Climate Change Conference.^[76] Further material was provided in the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories.^[77]

Other activities[edit | edit source]

The IPCC concentrates its activities on the tasks allotted to it by the relevant WMO Executive Council and UNEP Governing Council resolutions and decisions as well as on actions in support of the UNFCCC process.^[10] While the preparation of the assessment reports is a major IPCC function, it also supports other activities, such as the Data Distribution Centre,^[78] which helps manage data related to IPCC reports.

The IPCC has a Gender Policy and Implementation Plan^[79] dedicated to mainstreaming gender in its work in an inclusive and respectful manner, where there is balance in participation, and all have equal opportunity.

Communications and dissemination activities[edit | edit source]

Already in the Fifth Assessment Report, the IPCC had enhanced its communications activities, for instance by making the approved report and press release available to registered media under embargo before the release,^[80] and expanding its outreach activities with an outreach calendar.^[81] At the start of the Sixth Assessment Report cycle, the IPCC held an Expert Meeting on Communication in February 2016, bringing together members of the old and new Bureau and Technical Support Units with communications experts and practitioners. This meeting produced a series of recommendations.^[82] Many of these were taken up subsequently by the IPCC, such as bringing people with communications expertise into the Working Group Technical Support Units, and considering communications questions early on in the preparation of reports.

This increasing professionalism in IPCC communications was followed by a significant increase in the media coverage of some IPCC reports such as the Special Report on Global Warming of 1.5ºC in 2018 and "Climate Change 2021: The Physical Science Basis" (the Working Group I contribution to the Sixth Assessment Report) in 2021, as well as public interest reflected in the youth and other movements that emerged in 2018.^[83]

The importance of IPCC reports for public awareness of climate change and related policymaking has led to number of academic studies of IPCC communications. The journal "Climatic Change" published a "Topical Collection" on IPCC communications with contributions from communications scientists and IPCC insiders, launched at the annual climate conference COP26 in Glasgow.^[84][85]

Archiving[edit | edit source]

Papers and electronic files of certain working groups of the IPCC, including reviews and comments on drafts of their Assessment Reports, are archived at the Environmental Science and Public Policy Archives in the Harvard Library, as well as on the IPCC website.^[86]

Challenges and controversies[edit | edit source]

The assessment reports and special reports by IPCC have attracted criticism both from those who say they exaggerate the risks and those who argue they understate them.^[87] The global IPCC consensus approach has been challenged internally and externally.^[88][89]

Conservative nature of IPCC reports[edit | edit source]

Some critics have contended that the IPCC reports tend to be conservative by consistently underestimating the pace and impacts of global warming,^[87] and report only the "lowest common denominator" findings.^[90] In 2007 Stefan Rahmstorf, professor of physics and oceanography at Potsdam University, stated: "In a way, it is one of the strengths of the IPCC to be very conservative and cautious and not overstate any climate change risk".^[91] IPCC reports are intended to inform policymakers and others about the state of knowledge on climate change by assessing the findings of the thousands of scientific papers available on the subject at a given time in a process with multiple drafts and reviews. Individual publications, including those appearing just after the release of an IPCC report, may have different conclusions, leading to criticism that the IPCC is either overly alarmist or excessively conservative. New findings are reflected in the next assessment. ^{[92] [93]}

Potential political influence[edit | edit source]

A potential political influence on the IPCC has been documented by the release of a memo by ExxonMobil to the Bush administration in the United States in 2002, and its effects on the IPCC's leadership. The memo led to strong Bush administration lobbying, evidently at the behest of ExxonMobil, to oust Robert Watson, a climate scientist, from the IPCC chairmanship, and to have him replaced by Rajendra Pachauri, who was seen at the time as more mild-mannered and industry-friendly.^[94]

Governments form the membership of the IPCC, and are the prime audience for IPCC reports. IPCC rules gives them a formal role in the scoping, preparation and approval of reports. ^[95] For instance governments take part in the review process and work with authors to approve the Summary for Policymakers of reports. But some activists have argued that governments abuse this role to influence the outcome of reports. ^[96]

Controversy and review after Fourth Assessment Report in 2007[edit | edit source]

The IPCC came under unprecedented media scrutiny in 2009 in the run-up to the Copenhagen climate conference. This followed the leak of emails from climate scientists (so called "Climatic Research Unit email controversy"), many of whom were IPCC authors of the Fourth Assessment Report which was published in 2007. The discovery of an error in this report about the projected date for melting of Himalayan glaciers in early 2010 put the IPCC under further pressure.^[97] Scientific bodies upheld the general findings of the Fourth Assessment Report and the IPCC’s approach.^[98][99] But the Chair of the IPCC and UN Secretary-General invited the InterAcademy Council to carry out an independent review of IPCC procedures (see below).^[100]

InterAcademy Council review in 2010[edit | edit source]

In March 2010, at the invitation of the United Nations secretary-general and the chair of the IPCC, the InterAcademy Council (IAC) was asked to review the IPCC's processes for developing its reports.^[100][101] The IAC panel, chaired by Harold Tafler Shapiro, released its report on 1 September 2010.^[102] The panel made seven formal recommendations for improving the IPCC's assessment process. The IPCC implemented most of the review's recommendations by 2012, including the introduction of a protocol to handle errors in reports.^[103][104] Others included strengthening the science-review process and improving communications, but the IPCC did not adopt the proposal to appoint a full-time executive secretary.^[102][105]

Issues with consensual approach[edit | edit source]

Michael Oppenheimer, a long-time participant in the IPCC and coordinating lead author of the Fifth Assessment Report, conceded some limitations of the IPCC consensus approach and asked for concurring, smaller assessments of special problems instead of the large scale approach as in the previous IPCC assessment reports.^[89] Others see "mixed blessings" of the drive for consensus within the IPCC process and ask to include dissenting or minority positions^[106] or to improve statements about uncertainties.^[107][108]

Endorsements and awards[edit | edit source]

IPCC reports are the benchmark for climate science.^[109] There is widespread support for the IPCC in the scientific community, which is reflected in publications by other scientific bodies and experts.^[110][111] Various scientific bodies have issued official statements endorsing and concurring with the findings of the IPCC, for example:

• For the Third Assessment Report in 2001 endorsements came from the Canadian Foundation for Climate and Atmospheric Sciences,^[112] United States National Research Council^[113] and European Geosciences Union.^[114]
• For the Fourth Assessment Report in 2007 endorsements came from the International Council for Science (ICSU),^[115] and the Network of African Science Academies.^[116]

Nobel Peace Prize in 2007[edit | edit source]

Wikisource has original text related to this article:

Al Gore's Nobel Peace Prize acceptance speech

In December 2007, the IPCC was awarded the Nobel Peace Prize "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change". The award is shared with former U.S. Vice-president Al Gore for his work on climate change and the documentary An Inconvenient Truth.^[117]

Gulbenkian Prize for Humanity in 2022[edit | edit source]

In October 2022, the IPCC and the IPBES shared the Gulbenkian Prize for Humanity, because the two intergovernmental organisations "produce scientific knowledge, alert society, and inform decision-makers to make better choices for combatting climate change and the loss of biodiversity". ^[118]

See also[edit | edit source]

• Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services – Towards science-led government policy – Towards science-led government policy
• United Nations Framework Convention on Climate Change – 1994 international environmental treaty – 1994 international environmental treaty

References[edit | edit source]

Sources[edit | edit source]

External links[edit | edit source]

• Official website
• IPCC Data Distribution Centre Climate data and guidance on its use.