# The IPCC The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body responsible for assessing the science of climate change. Established in 1988 by the World Meteorological Organization and the United Nations Environment Programme, it does not conduct original research. Instead it reviews and synthesizes the published, peer-reviewed literature, producing comprehensive assessment reports roughly every six to seven years that have become the authoritative reference for governments worldwide. It shared the 2007 [[Nobel Peace Prize]] for this work. ## How It Works The IPCC is organized into three working groups — the physical science, impacts and adaptation, and mitigation — staffed by thousands of volunteer scientists nominated by member governments. Each report passes through multiple rounds of expert and government review, with every comment logged and answered on the public record. The most-read product is the Summary for Policymakers, whose wording is approved line by line by government delegates in a process that is sometimes mischaracterized as politicization. In practice the negotiation runs the other way: because every sentence must survive both scientific review and the unanimous sign-off of nearly two hundred governments, including major petrostates, the language tends to be *more* cautious than the underlying science, not less. This built-in conservatism is the key to understanding the IPCC. Its estimates of sea level rise, ice-sheet loss, and other impacts have repeatedly proven too low rather than too high, because consensus bodies gravitate toward the least controversial reading of the evidence. The reports also use a careful calibrated-uncertainty language — "virtually certain," "likely," "low confidence" — that conveys precise degrees of confidence but is easily quote-mined by critics who present any hedge as doubt about the whole. ## Assessment Reports and the Denial Response Six assessment cycles have been completed. The First (1990) helped launch the UN climate convention; the Third (2001) introduced the famous "hockey stick" reconstruction associated with [[Michael Mann]]; the Fourth (2007) drew the [[American Enterprise Institute]]'s reported offer of $10,000 to scientists willing to critique it; and the Sixth (2021–2023) concluded human influence on warming is "unequivocal." Each cycle coordinates the standardized [[Emissions Scenarios]] that [[Climate Models]] are run against. The IPCC has been a standing target for the denial movement precisely because it embodies the institutional [[The Scientific Consensus on Climate Change]]. The 2009 "Climategate" affair — stolen emails from climate scientists, misrepresented as evidence of fraud — and a handful of minor errors found in the voluminous Fourth Assessment were amplified into a campaign to discredit the entire enterprise. Multiple independent investigations cleared the scientists of wrongdoing, but the manufactured scandal achieved its aim of seeding public doubt during the run-up to the Copenhagen climate summit. ## Connections The IPCC institutionalizes [[The Scientific Consensus on Climate Change]], coordinates the [[Emissions Scenarios]] used by [[Climate Models]], and is the synthesizing hub of [[Climate Science]]. For the field overview, see [[Climate Science]].