Explainer: What Is the IPCC?

As the Trump administration withdraws the US from key discussions about the Intergovernmental Panel on Climate Change’s upcoming global climate assessment, Earth.Org looks at the UN body’s mission and history, and how its work has shaped global climate policy in the last three decades.

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Since Eunice Newton Foote recognized carbon dioxide’s heat-capturing effect in 1856, climate science has come a long way. Not only do we now fully understand what is causing our planet to heat up – we also know how to stop it, and have all the instruments to do so. We owe most of this knowledge to the Intergovernmental Panel on Climate Change, or IPCC, a UN body founded in 1988 to advance scientific knowledge about human-made climate change.

But on the heels of the hottest year in history, the comeback of a climate denier at the White House is threatening to slow down progress and compromise future global efforts to curb climate change.

As the US pulls out of this week’s IPCC meeting in Hangzhou, China, Earth.Org looks at the UN body’s mission and contribution to advancing understanding of climate change around the world – and how recent developments could impact its future.

What Is the IPCC?

Founded in 1988 by the World Meteorological Organization and the United Nations Environment Programme, the Intergovernmental Panel on Climate Change is the climate science arm of the United Nations.

Through comprehensive scientific assessments published every five to seven years, the group informs policymakers on the crisis and its potential future risks, and puts forward adaptation and mitigation recommendations. 

But the IPCC does not conduct its own research – rather, its job is to gather experts from various fields, who then study the thousands of scientific papers on climate science published each year and summarize them into comprehensive reports. Once completed, the reports are thoroughly reviewed in plenary sessions by UN member states, who need to unanimously approve and adopt them. 

During plenary sessions, which take place at least once a year, the hundreds of attendees from relevant ministries, agencies, and research institutions from both member countries and observer organizations also decide on the IPCC’s budget and work programme as well as the scope and outline of its upcoming reports.

Working Groups and Task Force

Three Working Groups are responsible for putting together IPCC reports, with each of them analyzing a different aspect of the climate crisis: Working Group I (The Physical Science Basis), Working Group II (Impacts, Adaptation and Vulnerability) and Working Group III (Mitigation of Climate Change). 

There is also a Task Force on National Greenhouse Gas Inventories, whose main objective is to develop and refine a methodology for the calculation of and reporting of national greenhouse gas emissions and removals. 

The Working Groups and Task Force handle the preparation of reports and select and manage the experts working on them as authors. 

The panel does not tell governments what to do, but rather assesses possible solutions. Their conclusions are not predictions of the future but rather projections based on different warming scenarios. 

IPCC Reports

Over 8,000 experts have volunteered their time to the IPCC assessment cycles – six completed to date – putting together 36 “comprehensive and balanced” reports on various climate-related topics.

Each assessment cycle concludes with the publishing of an Assessment Report, covering the state of scientific, technical, and socio-economic knowledge on climate change, its impacts and future risks, and strategies to mitigate them or slow them down. They come in four parts – a contribution from each of the three IPCC Working Groups, plus a Synthesis Report, which includes a Summary for Policymakers.  

In what some scientists termed “the bleakest warning yet,” the IPCC’s most recent assessment report found that the window to secure a liveable future is closing, and that “[t]he magnitude and rate of climate change and associated risks depend strongly on near-term mitigation and adaptation actions.”

More on the topic: 8 Key Findings from the IPCC Sixth Assessment Report

The IPCC also produced 14 Special Reports on topics agreed to by its member governments, ranging from the impact of aviation and land-use change to carbon dioxide capture and storage, renewable energy, and managing the risks of extreme weather events. These are also integrated into the Synthesis Report of the assessment cycle in which they were carried out.

As part of the seventh assessment cycle, which formally began in July 2023, the UN body is working on a special report on climate change and cities, the outline of which was agreed last year.

The IPCC’s contribution to global climate change understanding is further enhanced by six Methodology Reports, which provide practical guidelines for the preparation of greenhouse gas inventories. These are lists of sources and their associated emissions, and are used both by scientists to develop atmospheric models and by policymakers to assist in the development of emissions reduction strategies and policies.

Across the scientific community, the IPCC’s work is broadly viewed as the most comprehensive and reliable assessment of the climate crisis, undergoing “more scrutiny than any other documents in the history of science.” The group was awarded the Nobel Piece Prize in 2007 “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.”

Is Global Climate Action at a Crossroads?

Trump’s decision to pull out the US – the world’s second-largest emitter of planet-warming greenhouse gases – from IPCC matters has sparked outrage and concern among the scientific community.

Johan Rockström, an internationally acclaimed Earth scientist and Director of Germany’s Potsdam Institute for Climate Impact Research, said the move was “another irresponsible self-destructive US behaviour” that “will damage US science and society.” A few weeks earlier, Trump signed an executive order to withdraw the US from the Paris Agreement, the most significant global climate deal to date, and blocked financial contributions to the UN’s climate body – the UN Framework Convention on Climate Change – and the Green Climate Fund.

“If Trump were to revoke the US funding, there would likely be shortfalls and that would impact the ability to convene expert meetings and conduct assessments,” said Delta Merner from the Union of Concerned Scientists. The IPCC is funded by very few member states, and the US is among the biggest contributors. The UN body received nearly $1.45 million from the Biden administration in 2024 – more than a quarter of the $5.3-million budget.

This week’s talks in China aim to flesh out plans for the upcoming IPCC report and discuss whether it can be produced in time to inform a key 2028 UN “stocktake” of the global response to a warming planet. At the time of writing, the three-part report is scheduled for completion and release in late 2029. The US’s absence at the table will cast a shadow.

UN Secretary-General António Guterres said the Paris agreement “can survive” without the US, but warned that the country’s exit could leave the process “crippled.” But the same could be said for other international efforts to curb the climate crisis.

“Defunding the IPCC doesn’t just weaken global climate action potential – but it also leaves the US less prepared for a climate risk that directly threatens communities, the economy and national security here,” said Merner.

Featured image: Mark Speight/IPCC via Flickr.