The Intergovernmental Panel on Climate Change (IPCC) is a group made up of governments within the United Nations (UN). Its purpose is to "provide scientific information to governments so they can create climate policies." The World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) created the IPCC in 1988. The UN approved the creation of the IPCC later that same year. The IPCC has an office in Geneva, Switzerland, managed by the WMO. It has 195 member countries that help govern the IPCC. These countries choose a group of scientists to lead the IPCC’s work during an assessment cycle. A cycle usually lasts six to seven years. The group selects experts to write IPCC reports. Experts are chosen through a formal process by governments and other organizations. The IPCC has three working groups and a task force that handle its scientific work.

The IPCC shares information about what scientists know about climate change with governments. It does this by reviewing all scientific research related to climate change, including natural, economic, and social effects, as well as possible ways to respond. The IPCC does not do its own research. It tries to be fair and thorough. Thousands of scientists and experts volunteer to check the work. They gather important findings into "Assessment Reports" for leaders and the public. Experts have called this process the largest peer review in science. The IPCC was the first of three global science policy groups. The next groups were the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), created in 2012, and the Intergovernmental Science-Policy Panel on Chemicals, Waste and Pollution (ISPCWP), created in 2025.

Scientists and all member countries support the IPCC’s findings. This shows the IPCC is a trusted source on climate change. Governments, organizations, and the media often use the IPCC’s reports. These reports are important in yearly climate meetings held by the United Nations Framework Convention on Climate Change (UNFCCC). The IPCC’s Fifth Assessment Report helped shape the Paris Agreement in 2015. The IPCC shared the 2007 Nobel Peace Prize with Al Gore for helping people understand climate change.

The seventh assessment cycle of the IPCC began in 2023. In August 2021, the IPCC released its Working Group I report on the physical science basis of climate change as part of the Sixth Assessment Report. In February 2022, the IPCC published its Working Group II report on impacts and adaptation. It released its Working Group III report on reducing climate change in April 2022. The Sixth Assessment Report ended with a Synthesis Report in March 2023.

During the Sixth Assessment Report, the IPCC published three special reports. The most important one was the Special Report on Global Warming of 1.5°C in 2018. Other reports were published in 2019: one on climate change and land, and one on the ocean and cryosphere. The IPCC updated its methods in 2019, making the sixth assessment cycle the most ambitious in its history.

In January 2026, United States President Donald Trump announced that the United States would leave the organization.

Origins

The group that came before the IPCC was called the Advisory Group on Greenhouse Gases (AGGG). Three organizations created the AGGG in 1986. These were the International Council of Scientific Unions, the United Nations Environment Programme (UNEP), and the World Meteorological Organization (WMO). The AGGG looked at scientific research about greenhouse gases. It also studied how greenhouse gas levels were increasing. At that time, climate science was becoming more complex and involved more areas of study. This small group of scientists did not have enough resources to handle all the work.

The United States Environmental Protection Agency wanted an international agreement to limit greenhouse gas emissions. The Reagan administration was concerned that independent scientists might have too much influence. Because of this, the WMO and UNEP created the IPCC as an international organization in 1988. Scientists join the IPCC as both experts and representatives of governments. The IPCC creates reports supported by all top scientists in the field. All member governments must agree to these reports by consensus. This means the IPCC works with both scientists and governments. Its role is to inform governments about what scientists know about climate change. It also looks at the effects of climate change and possible ways to address it. The IPCC does this by reviewing scientific studies that have been checked by experts.

In 1988, the United Nations approved the creation of the IPCC. A resolution by the General Assembly said that human activities could change the climate. This could cause serious economic and social problems. The resolution also noted that higher levels of greenhouse gases could warm the planet. This warming could lead to rising sea levels. If steps to address these issues were not taken quickly, the effects on people would be very serious.

Organization

The IPCC does not perform original research. It creates detailed reports that summarize what scientists know about climate change. It also writes reports on specific climate-related topics and develops methods. These methods help countries measure their greenhouse gas emissions and how much carbon is removed by natural processes. Its reports build on earlier studies and scientific papers. Over six reports, the evidence shows that climate change is happening and that human actions are the main cause.

The IPCC follows rules called the "Principles Governing IPCC Work." These rules say the IPCC will evaluate:
• the risks of climate change caused by human activities,
• the possible effects of climate change, and
• ways to prevent or reduce climate change.

IPCC reports are detailed, fair, open, and clear. They include all information important for understanding climate change. This includes scientific, technical, and social and economic data. The reports do not suggest specific policies but may discuss factors that influence policy decisions.

The IPCC has the following structure:
• IPCC Panel: Meets in full meetings about twice a year. It may meet more often when approving reports. It manages the IPCC’s structure, procedures, work plan, and budget. It approves IPCC reports. The Panel is the main decision-making group of the IPCC.
• Chair: Elected by the Panel. Leads the Bureau and other groups. Represents the IPCC.
• Bureau: Elected by the Panel. Has 34 members from different regions. Includes the Chair and three Vice-Chairs. Provides leadership for the IPCC’s three Working Groups and Task Force. Helps the Panel with scientific and technical guidance.
• Working Groups: Each has two Co-Chairs, one from a developed and one from a developing country. A technical team supports each group. Working Group sessions approve the Summary for Policymakers in reports. Each group has a Bureau made up of its Co-Chairs and Vice-Chairs, who also serve on the IPCC Bureau.
– Working Group I: Studies the science of the climate system and climate change. Co-Chairs: Robert Vautard (France) and Xiaoye Zhang (China).
– Working Group II: Studies the effects of climate change on people and nature and ways to adapt. Co-Chairs: Bart van den Hurk (Netherlands) and Winston Chow (Singapore).
– Working Group III: Studies ways to reduce greenhouse gas emissions (called "mitigation"). Co-Chairs: Katherine Calvin (United States) and Joy Jacqueline Pereira (Malaysia).
• Task Force on National Greenhouse Gas Inventories: Creates methods for measuring emissions. Co-Chairs: Takeshi Enoki (Japan) and Mazhar Hayat (Pakistan). The Task Force Bureau includes two Co-Chairs and 12 members.
• Executive Committee: Includes the Chair, Vice-Chairs, and Co-Chairs of Working Groups and the Task Force. Handles urgent issues between Panel meetings.
• Secretariat: Manages daily activities, supports the Chair and Bureau, and communicates with governments. Supported by UNEP and WMO.

The current IPCC Chair is Jim Skea, a British energy scientist. He was elected in July 2023. His predecessor was Hoesung Lee (Korea), elected in 2015. Earlier chairs were Rajendra K. Pachauri (2002), Robert Watson (1997), and Bert Bolin (1988).

The IPCC Panel includes government representatives. They attend IPCC meetings and Working Group sessions. Non-governmental and international organizations may observe meetings. Only invited people attend IPCC meetings. At the 48th Panel Session in 2018, about 500 people from 130 countries attended, including 290 government officials and 60 observers. Media are allowed to attend opening ceremonies of Panel and Lead Author Meetings. Other meetings are closed to the public.

The IPCC receives money from a special trust fund. UNEP and WMO created the fund in 1989. Governments and other organizations give money voluntarily. WMO covers the secretariat’s costs and sets financial rules. The Panel decides the annual budget.

In 2021, the IPCC’s budget was about six million euros, funded by 195 UN member states. The top contributors were the United States, Japan, France, Germany, and Norway. Some countries, especially developing ones, contribute by hosting IPCC meetings. In 2022, the budget was about eight million euros.

The IPCC follows decisions made by UNEP and WMO, which created the IPCC. It also supports the UNFCCC. Its main work is preparing assessments and reports. It also helps manage data through the Data Distribution Centre.

The IPCC has a "Gender Policy and Implementation Plan" to ensure equal participation and respect for all. It aims to include everyone fairly in its work.

The IPCC improved its communication efforts for the Fifth Assessment Report. For example, it shared approved reports and press releases with media before public release. It also created an outreach calendar. In 2016, the IPCC held a meeting about communication for the Sixth Assessment Report. Experts and Bureau members discussed ways to improve communication. Recommendations included hiring communication experts and considering communication early in report writing.

After these changes, the IPCC saw more media coverage of its reports. This was especially true for the 2018 Special Report on Global Warming of 1.5 °C and the 2021 report on the physical science basis of climate change. Public interest also grew, leading to youth-led movements in 2018.

IPCC reports are important for raising public awareness and helping governments make policies. This has led to many studies about how the IPCC communicates its findings.

The IPCC stores its reports and electronic files on its website. These include feedback from experts on draft reports. The Harvard Library also archives IPCC reports in its Environmental Science and Public Policy Archives.

Assessment reports

Between 1990 and 2023, the IPCC published six detailed reports that review the latest climate science. The IPCC also created 14 special reports on specific topics. Each assessment report has four parts: contributions from each of the three working groups and a synthesis report. The synthesis report combines the working group contributions and any special reports made during that assessment cycle.

The IPCC does not conduct research or monitor climate data. Instead, it reviews scientific papers and results from other organizations. The IPCC sets a deadline for including scientific papers in a report. Reports do not include information that appears after this deadline. However, key findings and confidence levels in science improve with each new report. Each report also highlights areas where science has improved and areas needing more research.

The First Assessment Report was published in 1990 and updated in 1992. New editions of the IPCC Assessment Reports were published every six years.

Focal points from member states and observer organizations provide lists of people to the IPCC Bureau. The Bureau uses these lists to select authors, prioritizing scientific excellence and diverse viewpoints. Authors can include researchers, people from the private sector, and experts from NGOs.

The IPCC Bureau selects report authors based on government nominations. Lead authors review published information about climate change, focusing on peer-reviewed sources. Non-peer-reviewed sources, such as government or NGO reports, may be used if they are high quality.

Authors write drafts of full reports, divided into chapters. They also create a technical summary and a summary for policymakers. Each chapter has multiple authors, including coordinating lead authors, lead authors, and contributing authors. Coordinating lead authors organize contributions and ensure they follow formatting rules. They report to working group co-chairs. Lead authors write sections and invite contributing authors to add text, graphs, or data. Review editors ensure authors address feedback during two review stages: one for experts and researchers, and one for government representatives.

The IPCC Bureau chooses authors to ensure a range of views, expertise, and geographic representation. This includes experts from both developing and developed countries, as well as a balance between male and female authors. It also balances those with prior IPCC experience and new participants.

Scientists who work on IPCC reports do not receive payment. They rely on their home institutions or other jobs for income. The work is time-consuming and may affect their research. This has raised concerns that some scientists might avoid participating. Over 3,000 authors have contributed to IPCC reports since the organization began.

Expert reviewers comment on drafts at different stages. Reviewers come from member governments, IPCC observers, or anyone with relevant expertise.

The review process has three stages. First, experts review the first draft of chapters. Next, governments and experts review revised chapter drafts and the first draft of the Summary for Policymakers. Finally, governments review the revised Summary for Policymakers. All comments and responses are kept in an open archive for at least five years. Government representatives and authors review the Summary for Policymakers line by line to ensure it accurately summarizes the report. This final review happens during working group or Panel sessions.

Documents receive different types of endorsement:
– Approval: Material is discussed and agreed upon line by line. Working Groups approve their summaries for policymakers, and the Panel approves the Synthesis Report’s summary.
– Adoption: Sections are approved individually, not line by line. The Panel adopts the full Synthesis Report and Overview Chapters of Methodology Reports.
– Acceptance: Material is not reviewed line by line but presents a balanced view. Working Groups accept their reports, and the Panel accepts summaries after approval.

The IPCC’s First Assessment Report (FAR) was published in 1990. It provided an overview of climate science, noted uncertainties, and stated that human activity increases greenhouse gases, causing Earth’s warming. This report led to the creation of the United Nations Framework Convention on Climate Change (UNFCCC).

The Second Assessment Report (SAR) was published in 1995. It confirmed human influence on climate change and supported the Kyoto Protocol negotiations.

The Third Assessment Report (TAR) was completed in 2001. It showed more evidence that human activity caused most of the global warming in the past 50 years. It included a graph showing a sharp temperature rise, called the "hockey stick," and discussed climate change adaptation.

The Fourth Assessment Report (AR4) was published in 2007. It stated that climate change is certain and raised global awareness. The IPCC shared the Nobel Peace Prize that year for its work.

The Fifth Assessment Report (AR5) was published in 2013 and 2014. It confirmed climate change and warned of its impacts.

Other reports

The IPCC also creates other types of reports. It makes Special Reports on topics suggested by governments or groups that watch over the IPCC. From 1994 to 2019, the IPCC published 14 special reports. Today, more than one working group usually works together to create a special report. The process for making and approving these reports is the same as for assessment reports.

During the fifth assessment cycle, the IPCC made two special reports. It finished the Special Report on Renewable Energy Sources and Climate Change Mitigation in 2011. Working Group III created this report. The report looked at ways to use different types of renewable energy instead of fossil fuels. It said the cost of most renewable technologies had decreased and might decrease even more with new technology. It explained that renewable energy could help more people get access to energy. The report studied 164 scenarios showing how renewable energy could help stop climate change. In more than half of these scenarios, renewable energy would provide more than 27% of the primary energy supply by mid-century. This would be more than double the 13% share in 2008. In scenarios with the highest use of renewable energy, it would provide 77% of energy by 2050.

Later in 2011, the IPCC released the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. This report was made by Working Groups I and II. It was the first time two working groups worked together on a special report. The report explained how climate change has changed extreme weather events. It also showed how policies to avoid or prepare for these events can reduce their effects. Policies to respond to and recover from events can also help societies become more resilient.

During the sixth assessment cycle, the IPCC made three special reports. This was the most ambitious cycle in IPCC history. The UNFCCC set a goal to keep global warming well below 2°C (36°F) and try to keep it at 1.5°C (34.7°F) after the Paris Agreement in 2015. At that time, there was little understanding of what warming at 1.5°C meant. There was also little research on how the effects of 1.5°C would differ from 2°C, or how to keep warming at 1.5°C. The UNFCCC asked the IPCC to prepare a report on global warming of 1.5°C. The IPCC released the Special Report on Global Warming of 1.5°C (SR15) in 2018. The report said it was possible to keep warming below 1.5°C during the 21st century. However, this would require major reductions in emissions and rapid changes in all areas of society. The report showed that warming at 2°C would have much worse effects than warming at 1.5°C. In other words, every degree of warming matters. SR15 had a major impact on the media and public. It placed the 1.5°C target at the center of climate activism.

In 2019, the IPCC released two more special reports that studied different parts of the climate system. The Special Report on Climate Change and Land looked at how land use affects the climate. It studied emissions from farming and forestry, not from energy or transport. It also studied how climate change is affecting land. All three IPCC working groups and the Task Force on National Greenhouse Gas Inventories worked together on this report. The report said climate change is adding to the pressures we place on the land we use for living and growing food. It said that keeping warming well below 2°C will only be possible if emissions are reduced in all sectors, including land and food.

The Special Report on the Ocean and Cryosphere in a Changing Climate studied how the ocean and frozen parts of the planet interact with climate change. (The cryosphere includes ice sheets, glaciers, and permafrost.) Working Groups I and II created this report. It showed the need to address changes in the ocean and cryosphere. It also explained how adaptation can help achieve sustainable development.

The IPCC has a National Greenhouse Gas Inventories Programme. It helps countries report their greenhouse gas emissions by developing methods and software. The IPCC's Task Force on National Greenhouse Gas Inventories (TFI) has managed this program since 1998. Japan's Institute for Global Environmental Strategies hosts the TFI's Technical Support Unit.

The IPCC released its first Methodology Report, the IPCC Guidelines for National Greenhouse Gas Inventories, in 1994. The Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories updated this report. Two "good practice reports" complete these guidelines: the Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories and the Good Practice Guidance for Land Use, Land-Use Change and Forestry. Parties to the UNFCCC and its Kyoto Protocol use the 1996 guidelines and the two good practice reports for their annual emissions reports.

The 2006 IPCC Guidelines for National Greenhouse Gas Inventories updated these methods further. They include many "default emission factors," which are used to estimate emissions for different activities. The IPCC created this version of the guidelines at the request of the UNFCCC. The UNFCCC accepted them for use at its 2013 Climate Change Conference, COP19, in Warsaw. The IPCC added more information in its 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories.

The TFI has started preparing a methodology report on short-lived climate forcers (SLCFs). It will finish this report during the next assessment cycle, the seventh.

Challenges and controversies

The IPCC reports also face criticism. Some people say the reports overstate the risks of climate change, while others say they understate the risks. The IPCC's method of reaching agreement has faced challenges from inside and outside the organization.

Some scientists argue that IPCC reports are too cautious when describing climate risks. In 2012, it was reported that some scientists criticized the IPCC for consistently underestimating how quickly global warming is happening and its effects. They believe this leads to findings that are the "simplest or safest answer that everyone can agree on." Similar claims were made by scientists who noticed that recent IPCC reports focused more on lower temperature goals, like 1.5°C, and gave less attention to higher temperatures, such as 2°C, even though current trends suggest higher temperatures are more likely.

David Biello, writing in Scientific American, says the IPCC reports give conservative estimates because they must agree on findings among government representatives. Science editor Brooks Hanson wrote in 2010 that IPCC reports have underestimated how fast climate change is happening and overestimated how well societies can reduce greenhouse gas emissions.

Climate scientist James E. Hansen argues that the IPCC's cautious approach underestimates the risk of sea-level rise, which could flood many low-lying areas, such as the southern third of Florida. In January 2024, he told the Guardian that the world has entered the 1.5°C temperature range. He added that passing this milestone shows the United Nations and the IPCC may not be accurately addressing the issue.

Roger A. Pielke Sr. said humans are changing the climate in many ways beyond just carbon dioxide emissions. He argued the IPCC has been too cautious in recognizing these changes.

Stefan Rahmstorf, a professor at the University of Potsdam, said in 2007 that the IPCC's cautious approach has benefits. He argued that being careful helps ensure reports are reliable. IPCC reports summarize thousands of scientific studies to inform policymakers. Individual studies may have different conclusions than IPCC reports, especially those published after a report is released. This can lead to criticism that the IPCC is either too alarmist or too conservative. New findings are not considered until the next assessment report is made.

In 2002, a memo from ExxonMobil to the U.S. government suggested possible political influence on the IPCC. This led to pressure to replace Robert Watson, a climate scientist, as IPCC chair with Rajendra Pachauri, who was seen as more friendly to industry interests.

Governments form the IPCC and are its main audience. They have a formal role in shaping reports, including reviewing and approving summaries for policymakers. However, some activists say governments use this role to influence report outcomes.

In 2023, pressure from Brazil and Argentina, countries with large beef industries, caused the IPCC to remove text recommending plant-based diets. An earlier draft of the report had stated that plant-based diets could reduce greenhouse gas emissions by up to 50% compared to Western diets.

The IPCC faced intense media scrutiny in 2009 before the Copenhagen climate conference. This included the "Climatic Research Unit email controversy," where emails from scientists involved in the 2007 Fourth Assessment Report were leaked. An error in the report about Himalayan glaciers melting by 2035 added to the pressure. Scientific groups supported the overall findings of the report but called for the IPCC to review its processes.

After the 2009 release of the Fourth Assessment Report, the IPCC was criticized for bias and inaccuracies. In 2010, the U.N. Secretary-General and the IPCC chair asked the InterAcademy Council (IAC) to review the IPCC's processes. The IAC recommended improving management, conflict-of-interest policies, and the review process. Most recommendations were implemented by 2012, including a protocol for handling errors. However, the IPCC did not adopt a proposal to hire a full-time executive secretary.

Michael Oppenheimer, a long-time IPCC participant, said the consensus approach has limitations. He suggested smaller, focused assessments instead of large-scale reports. Others argue that including minority opinions and clarifying uncertainties could improve the IPCC's work.

Some criticism has come from experts invited to contribute to IPCC reports. For example, John Christy, a contributing author, said the process makes it hard to establish scientific consensus because authors and reviewers have limited influence. Christopher Landsea, a hurricane researcher, said he could not continue contributing to the IPCC after disagreeing with comments made by another scientist.

Endorsements and awards

The IPCC reports are the main reference for climate science. Many scientists support the IPCC's work. Other scientific groups and experts have also shown agreement. Official statements from several scientific organizations back the IPCC's findings. For example:

• The Third Assessment Report from 2001 received support from the Canadian Foundation for Climate and Atmospheric Sciences, the United States National Research Council, and the European Geosciences Union.
• The Fourth Assessment Report from 2007 received support from the International Council for Science (ICSU) and the Network of African Science Academies.

In December 2007, the IPCC was awarded the Nobel Peace Prize for helping to increase understanding of human-caused climate change and for creating the basis for actions to address this issue. The prize was shared with former U.S. Vice President Al Gore for his work on climate change and the documentary An Inconvenient Truth.

In October 2022, the IPCC and IPBES received the Gulbenkian Prize for Humanity. These two international organizations won the prize for producing scientific knowledge, raising awareness about important issues, and helping leaders make informed decisions to fight climate change and protect biodiversity.