Intergovernmental Panel on Climate Change

• 1. Introduction

  ›

  The Intergovernmental Panel on Climate Change was born from an unusual political tension. In 1988, the Reagan administration worried that if independent scientists were left to shape international climate policy on their own, governments would lose control of the conversation. So the United States pushed for a body where science and government would be intertwined from the start. The result was the IPCC, co-created by the World Meteorological Organization and the United Nations Environment Programme, and later endorsed by the UN General Assembly that same year.

  What makes the IPCC remarkable is what it does not do. It conducts no original research. It runs no laboratories. It employs no permanent scientific staff in the conventional sense. Instead, it convenes thousands of volunteers, scientists from universities, government agencies, and NGOs around the world, and asks them to read everything published on climate change and then agree on what it means.

  The question at the heart of this documentary is how such an unwieldy, consensus-driven body became the most authoritative voice on one of the most contested scientific and political questions in modern history. And what happens when that authority is tested from all sides at once.

• 2. Before the IPCC

  ›

  Three organizations created a predecessor body called the Advisory Group on Greenhouse Gases in 1986. The International Council of Scientific Unions, UNEP, and the WMO formed the AGGG to review research on greenhouse gases and track their rising concentrations in the atmosphere.

  Climate science was expanding rapidly in the mid-1980s. It was pulling in disciplines that had never worked together before, from oceanography to economics to atmospheric physics. The small team of scientists in the AGGG simply lacked the resources to keep pace.

  The United States Environmental Protection Agency, meanwhile, was pushing for an international convention to restrict greenhouse gas emissions. The Reagan administration's concern was that if independent scientists drove that process, the United States would have little leverage over what the science was seen to say. So Washington backed a different model, one where governments themselves would be at the table when findings were produced and endorsed. That political calculation gave birth to the IPCC's unusual dual identity as both a scientific body and an organization of governments.

  The United Nations General Assembly resolution that endorsed the IPCC's creation in 1988 was unusually blunt about the stakes. It noted that human activity could change the climate, that rising greenhouse gas concentrations could warm the planet and raise sea levels, and that the effects on humanity would be disastrous if timely steps were not taken. The AGGG, the small group that preceded the IPCC, was quietly absorbed into the new structure.

• 3. How the Machine Works

  ›

  A typical chapter in an IPCC assessment report is written by two coordinating lead authors, ten to fifteen lead authors, and a larger number of contributing authors. None of them are paid by the IPCC for this work. All of them volunteer, relying on salaries from their home institutions.

  The selection process begins with governments and observer organizations nominating candidates. The Bureau of the relevant Working Group then appoints authors from those lists, though it retains the right to choose people who were never nominated if scientific excellence or diversity of viewpoint requires it. The Bureau also seeks a balance between developed and developing countries, between experienced IPCC authors and newcomers, and between men and women.

  Once authors are in place, the review process runs in multiple stages. A first draft goes to external experts only. A revised draft then goes to both experts and government representatives. The Summary for Policymakers, the document most likely to be read by ministers and negotiators, is reviewed line by line with government representatives in the room. This is the stage where political pressure most visibly meets scientific language. Review comments and author responses must remain in an open archive for at least five years after a report is published.

  More than 3,000 coordinating lead authors, lead authors, and review editors have participated in IPCC reports since the body was created. The work can be disruptive to a scientist's research program, and there has been ongoing concern that the demands of the process discourage some qualified scientists from taking part.

• 4. From Uncertainty to Code Red

  ›

  The First Assessment Report, published in 1990, was measured in its language. The authors said they were certain that greenhouse gases were increasing because of human activity and that this was resulting in warming. But the report also catalogued uncertainties and acknowledged the limits of what scientists could say with confidence at the time. Its most concrete legacy was that it helped establish the United Nations Framework Convention on Climate Change.

  By 1995, the Second Assessment Report was prepared to go further, stating that there was a discernible human influence on global climate. That phrasing, cautious as it sounds, was significant. It provided key scientific material for the negotiations that led to the Kyoto Protocol.

  The Third Assessment Report in 2001 introduced what became known as the "hockey stick" graph, a reconstruction of global temperatures going back to the year 1000. The sharp upward turn in recent decades made the image immediately legible to general audiences. That report also found that most of the warming seen over the previous fifty years was due to human activity.

  The Fourth Assessment Report in 2007 opened with a sentence that had been carefully negotiated: "Warming of the climate system is unequivocal." That year, the IPCC and former U.S. Vice-President Al Gore shared the Nobel Peace Prize for contributions to understanding climate change. In December 2007, the Nobel committee cited the IPCC's efforts to build up and disseminate knowledge about man-made climate change and to lay foundations for the measures needed to counteract it.

  By August 2021, UN Secretary-General Antonio Guterres described the Working Group I contribution to the Sixth Assessment Report as "code red for humanity." The Guardian called it the "starkest warning yet" of major inevitable and irreversible climate changes. The report confirmed that climate changes not seen in thousands of years were already underway in every region, and that sea-level rise would remain irreversible over hundreds of thousands of years even with strong emission reductions.

• 5. The 1.5 Degree Report

  ›

  When the Paris Agreement was reached at COP21 in 2015, it set a goal of keeping warming well below 2 degrees Celsius while trying to hold it to 1.5 degrees. There was one problem. Almost no one could say with scientific precision what the difference between those two targets actually meant in practice.

  The UNFCCC invited the IPCC to fill that gap, and the resulting Special Report on Global Warming of 1.5 degrees Celsius was published in 2018. It showed that staying below 1.5 degrees was physically possible during the 21st century, but only through deep cuts in emissions and rapid, far-reaching changes across all sectors of society. It also showed that every fraction of additional warming carried meaningfully more severe consequences than the fraction before it.

  The report had an impact on public debate that the IPCC had not seen before. The 1.5-degree target moved from a diplomatic compromise to the rallying point of a global climate movement. Youth activism surged in 2018, and the report's findings were central to that mobilization. The IPCC's communications team had expanded its outreach work deliberately in the years leading up to this moment, following an Expert Meeting on Communication held in February 2016. Bringing communications expertise into the Working Group Technical Support Units had been one of the concrete steps taken after that meeting.

  The Special Report on Climate Change and Land, released in 2019, added another dimension. It found that reducing emissions from farming, forestry, and land use would be essential to keeping warming well below 2 degrees. That report was a collaboration among all three Working Groups and the Task Force on National Greenhouse Gas Inventories, the most complex collaborative structure the IPCC had assembled for a special report up to that point.

• 6. Pressures and Disputes

  ›

  Climate scientist James E. Hansen has argued that the IPCC's conservatism seriously underestimates the risk of sea-level rise on the scale of meters, enough to inundate areas such as the southern third of Florida. In January 2024, he told the Guardian that the panel's framing of the 1.5-degree milestone reflected a story he described in blunt terms as inaccurate.

  Some critics take a different view of the same pattern. Stefan Rahmstorf, a professor of physics and oceanography at the University of Potsdam, argued in 2007 that the IPCC's caution was in fact one of its strengths. Being conservative, he argued, made the body harder to attack and more durable as an authority.

  Political interference has also appeared in more direct forms. A memo from ExxonMobil to the Bush administration in 2002 led to active lobbying by the Bush White House to remove Robert Watson as IPCC chair and replace him with Rajendra Pachauri, who was considered more industry-friendly at the time. Watson had been elected to the role in 1997.

  In 2023, it was reported that Brazil and Argentina, both countries with large beef industries, pressured the IPCC to drop text recommending plant-based diets from a report. A leaked earlier draft had included language stating that plant-based diets could reduce greenhouse gas emissions by up to 50 percent compared to an average emission-intensive Western diet.

  The InterAcademy Council review of 2010 addressed a cluster of these tensions directly. The IAC panel, chaired by Harold Tafler Shapiro, released its report on the 1st of September 2010, after being asked to examine the IPCC's processes in the wake of controversies including an error about Himalayan glacier melt in the Fourth Assessment Report. The IAC made seven formal recommendations, and the IPCC implemented most of them by 2012, including a new protocol for handling errors in published reports.

• 7. Budget, Membership, and Awards

  ›

  In 2021, the IPCC operated on an annual budget of approximately six million euros, contributed voluntarily by its 195 member states. By 2022, that figure had risen to a little less than eight million euros. The countries contributing the most money in 2021 included the United States, Japan, France, Germany, and Norway. Developing countries often contribute in other ways, by hosting IPCC meetings rather than providing direct financial support.

  The WMO covers the operating costs of the IPCC secretariat in Geneva and sets the body's financial regulations. The trust fund that finances IPCC activities was established by UNEP and the WMO in 1989. The Panel itself sets the annual budget.

  British energy scientist Jim Skea has served as IPCC Chair since the 28th of July 2023, hosted by the International Institute for Environment and Development. Before Skea, Korean economist Hoesung Lee held the role after being elected in 2015. The chair before Lee was Rajendra K. Pachauri, elected in 2002, and before him Robert Watson, elected in 1997. The first IPCC chair was Bert Bolin, elected when the body was founded in 1988.

  In October 2022, the IPCC and the Intergovernmental Platform on Biodiversity and Ecosystem Services shared the Gulbenkian Prize for Humanity. The two bodies were recognized for producing scientific knowledge, alerting society, and informing decision-makers about climate change and biodiversity loss. In January 2026, U.S. President Donald Trump announced that the United States would withdraw from the IPCC, removing the organization's largest financial contributor from membership.