The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body responsible for assessing scientific knowledge about climate change. Established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), it evaluates research on climate processes, environmental and socioeconomic impacts, and possible responses. It does not conduct original research or operate climate-monitoring systems. Its reports are intended to inform policy without prescribing particular policies. The IPCC has 195 member countries. (ipcc.ch)
Origins and institutional role
The IPCC was created to provide governments with regular assessments of the available scientific, technical, and socioeconomic information on climate change. The United Nations General Assembly endorsed its establishment in 1988. Its institutional design combines an intergovernmental decision-making body with expert authorship and review: governments determine the assessment programme, while specialists evaluate the underlying evidence. (ipcc.ch)
The First Assessment Report, published in 1990, contributed to the development of the United Nations Framework Convention on Climate Change (UNFCCC). The Second Assessment Report, issued in 1995, provided information used in negotiations preceding the Kyoto Protocol of 1997. In 2007, the IPCC shared the Nobel Peace Prize with Al Gore for work on understanding and communicating human-caused climate change. The IPCC supplies assessments to international negotiations rather than negotiating agreements itself. (ipcc.ch)
Organization and scientific scope
Representatives of member governments meet in plenary sessions to decide the work programme, budget, report outlines, and procedures, generally by consensus. They elect a scientific Bureau for each assessment cycle. Governments and observer organizations nominate experts; the relevant Bureau selects authors, considering expertise, geographical representation, gender balance, and the range of scientific perspectives. A Secretariat and technical support units support the assessment process. (ipcc.ch)
Scientific work is organized principally through three working groups:
- Working Group I assesses the physical science of the climate system, including observations, causes of change, and projections.
- Working Group II assesses impacts, vulnerability, and climate change adaptation in natural and human systems.
- Working Group III assesses climate change mitigation, including options for limiting emissions and enhancing greenhouse-gas removals. (ipcc.ch)
A separate Task Force on National Greenhouse Gas Inventories develops internationally agreed methods for estimating national greenhouse gas emissions and removals. These methodologies support reporting under the UNFCCC and the Paris Agreement. Its function differs from that of the working groups: it provides accounting methods rather than a comprehensive assessment of climate knowledge. (ipcc.ch)
Reports and assessment cycles
The IPCC produces comprehensive assessment reports, special reports on selected topics, and methodology reports. A comprehensive assessment normally includes contributions from the three working groups and a Synthesis Report that integrates their findings. Assessment cycles update the evidence base rather than simply reissue earlier conclusions. (ipcc.ch)
Following the first two assessments, the Third Assessment Report appeared in 2001, the Fourth in 2007, and the Fifth in 2013–2014. The Sixth Assessment Report concluded in March 2023. Its Synthesis Report assessed findings on warming, impacts, future risks, and response options, including their connections with sustainable development. (ipcc.ch)
The 2023 synthesis concluded that human activities, principally greenhouse-gas emissions, had unequivocally caused global warming. It reported global surface temperature in 2011–2020 at approximately 1.1°C above the 1850–1900 average. It also assessed changes in the ocean and cryosphere, sea level rise, and consequences for ecosystems and human communities. These figures describe the assessment’s specified historical periods, not a continuously updated estimate. (ipcc.ch)
The seventh assessment cycle began in July 2023. Its programme includes three working-group contributions, a Synthesis Report, and additional special and methodology reports. The Synthesis Report is planned for release by late 2029; this is a scheduled publication, not a completed assessment. (ipcc.ch)
Preparation, review, and approval
Authors synthesize scientific, technical, and socioeconomic literature, drawing on peer-reviewed research and other relevant publications. The first-order draft undergoes expert review; the second-order draft is reviewed by experts and governments. Authors respond to comments, while review editors oversee whether substantive comments and differing scientific views receive appropriate consideration. Review comments and responses are published to make the process traceable. (ipcc.ch)
Each major report includes a Summary for Policymakers. Government representatives approve this summary line by line in dialogue with the authors, ensuring consistency with the underlying assessment. The full working-group report is accepted rather than negotiated sentence by sentence. IPCC procedures distinguish approval, acceptance, and adoption, and provide a formal process for addressing alleged errors after publication. (ipcc.ch)
Evidence and uncertainty
IPCC assessments use calibrated language to distinguish the strength of evidence from the probability of an outcome. Confidence is a qualitative judgment based on the type, quantity, quality, and consistency of evidence, together with agreement among studies. Likelihood expresses quantified uncertainty: for example, “likely” corresponds to a probability of 66–100%, and “very likely” to 90–100%. These terms are not interchangeable. (ipcc.ch)
Projections based on climate models are conditional on assumptions about future emissions and other influences. The assessment framework allows authors to identify robust findings, unresolved disagreements, and evidence gaps. A low-confidence finding is not necessarily false; it indicates limitations in the available basis for assessment. Where supported, reports present numerical ranges or probability distributions alongside verbal uncertainty statements. (ipcc.ch)