The Intergovernmental Panel on Climate Change (IPCC) is an international organization established in 1988 by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO).
With its 195 member states, the IPCC is recognized by many as the world’s leading scientific authority on climate change. In 2007, it was awarded the Nobel Peace Prize for its central role in disseminating knowledge about climate change caused by humans and the measures needed to address it.
But what exactly is the IPCC doing to inform international climate action?
The IPCC: An interface between science and politics
The IPCC acts as an interface between the scientific community and political decision-making. Its role is not to produce new research or run climate models, but rather to analyze and synthesize the technical and socio-economic literature that has already been published. Based on this extensive literature, the IPCC produces periodic scientific assessments. They concern climate change, its impacts and future risks, as well as adaptation and mitigation measures. These assessments, which are recognized for their rigour and objectivity, provide governments with a solid basis on which to develop climate policies. These assessments also serve as a basis for international climate negotiations, such as those of the Conference of the Parties (COP) on climate change.
Although it was created by the United Nations, the IPCC operates autonomously, which ensures its integrity and the independence of its scientific conclusions from the UN agenda. Thus, it does not formulate specific policy recommendations, but informs decision-makers by presenting things like climate projections linked to various greenhouse gas emission scenarios and different risks related to climate change.
Assessment reports in three scientific domains
The IPCC produces assessment reports every 5 to 7 years, which outline the state of scientific knowledge on climate, its impacts, and possible adaptation and mitigation solutions. Six assessment cycles have already been completed and the seventh has been underway since July 2023.
Each assessment cycle comprises three main reports, each prepared by a specialist working group:
- Working Group I focuses on the physical scientific basis—the scientific foundations of the climate system and climate change (The Working Group I contribution to the Sixth Assessment Report, 2021).
- Working Group II deals with the consequences of climate change, as well as adaptation strategies and the vulnerability of human and natural systems (The Working Group II contribution to the Sixth Assessment Report, 2022).
- Working Group III is dedicated to studying ways to mitigate climate change, i.e. to reduce and stabilize greenhouse gas emissions (The Working Group III contribution to the Sixth Assessment Report, 2022).
In addition to these three working groups, there are also special teams, such as the one responsible for managing the national greenhouse gas inventories.
Overview of the other IPCC reports
In addition to its assessment reports, the IPCC also produces special reports. These are issued when a specific topic requires special attention or at the request of international organizations, such as the United Nations Framework Convention on Climate Change (UNFCCC). These special reports often involve several working groups, as they address cross-cutting issues.
During the sixth cycle, three special reports were published:
The IPCC also produces methodology reports, as well as guidelines for national greenhouse gas inventories. The guidelines published in 2006 and refined in 2019 are the international reference for ensuring reliable and comparable inventories.
Each assessment cycle concludes with a synthesis report, the latest of which was published in March 2023. This document summarizes the reports by the three working groups and the special reports. It offers a coherent overview of the knowledge on climate change, and its publication marks the transition to the next assessment cycle.
A rigorous collective review process
The preparation of an IPCC report is a complex process. It relies on the collaboration of hundreds or thousands of international experts.
The coordinating lead authors and the lead authors are collectively responsible for the content of their chapter. Their role is to analyze and synthesize thousands of scientific publications.
They are supported by hundreds of contributing authors with specialized knowledge or skills in a particular field. They help to ensure that the reports take the diversity of opinions expressed by the scientific community into account.
Young researchers, often at the beginning of their careers, support them in writing the different chapters. They also help create the figures and manage the references.
Who are the IPCC authors?
All IPCC authors are volunteers. They are selected for their scientific skills and experience, but also to represent a range of different scientific, technical and socio-economic perspectives.
The selection process is rigorous. In particular, it seeks to ensure a balance between the regions of the world, scientific disciplines, and the levels of development of countries. This balance helps to prevent the reports from disproportionately reflecting the perspective of one country or group of countries. It also ensures that certain important regional issues are not neglected. Gender parity is also one of the criteria to ensure the fairest and most inclusive representation possible.
To reflect the level of scientific certainty, key statements are accompanied by:
- An assessment of the confidence level, ranging from “very low” to “very high
- A likelihood scale ranging from “exceptionally unlikely” to “virtually certain”
This terminology, used uniformly in all recent reports, aims to improve the transparency and the understanding of the results. Once written, the reports go through several rounds of reviews:
- The first draft of the report is initially reviewed by thousands of experts.
- A second draft is submitted for comments by these experts and the governments.
- When the final version of the report is distributed to the governments, they make comments on the Summary for Policymakers, and on the overview in the case of methodology reports.
Summary for Policymakers: A meticulous approval process
The Summary for Policymakers presents the main findings of an IPCC synthesis report, in condensed form. It is approved line by line in a plenary session, by consensus of the 195 member states of the IPCC and in consultation with the scientific authors. The report’s statements are formulated as clearly, directly and unambiguously as possible, while taking the diversity of cultural and political contexts into account.
This approval process is often meticulous; it requires the member states to reach a consensus that is consistent with the state of science. The lead authors also ensure that any changes made to the text remain faithful to the main report and are scientifically valid.
