Intergovernmental Panel on Climate Change (IPCC)

The Intergovernmental Panel on Climate Change (IPCC) is the United Nations‑mandated body that synthesises the latest peer‑reviewed climate science, impacts, and mitigation knowledge for the benefit of governments and the public. Founded jointly by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988, the panel is unique in its global reach—195 member states participate, and its assessments are the only scientific reports that carry the explicit endorsement of the UN system. By translating complex research into policy‑relevant summaries, the IPCC has become the cornerstone of international climate negotiations, from the Kyoto Protocol to the Paris Agreement. ## Origins and Institutional Structure The IPCC’s creation was prompted by growing concerns in the late 1970s that rising greenhouse‑gas concentrations could alter the Earth’s climate system. UNEP’s Executive Director, Maurice Strong, and WMO’s Secretary‑General, Jacob Bjerknes, convened an inaugural meeting in Geneva in 1988, adopting a charter that defined the panel’s mandate to assess “the scientific, technical and socio‑economic information relevant for understanding the risk of human-induced climate change.” Governance rests with a Panel of 34 elected members, one from each UN region, who meet annually at a plenary session. The Panel elects a Chair and Vice‑Chairs; the current Chair, Hoesung Lee of South Korea, has served since 2015. An Executive Committee (ExCom) and a Bureau support the Panel, while three permanent Working Groups (WGs) and a Task Force on National Greenhouse Gas Inventories (TFI) carry out the substantive work. As of 2023, the IPCC draws on roughly 3,000 scientists from academia, research institutes, and NGOs, with about 800 authors contributing to each assessment cycle. ## Assessment Process and Working Groups Each assessment cycle follows a multi‑stage, transparent peer‑review process that can span five to seven years. Working Group I evaluates the physical science basis of climate change, WG II examines impacts, adaptation, and vulnerability, and WG III focuses on mitigation pathways and policy options. Draft chapters undergo two rounds of expert review, followed by a government review where all member states can comment. The final synthesis report is approved line‑by‑line at a plenary meeting, ensuring that the conclusions reflect both scientific consensus and governmental acceptance. The IPCC also maintains the TFI, which produces the annual “National Greenhouse Gas Inventory Reports” that standardise emissions accounting for the UNFCCC reporting process. This inventory framework underpins the transparency mechanism of the Paris Agreement, allowing countries to compare their mitigation efforts against a common baseline. ## Assessment Reports and Special Reports To date the IPCC has released six comprehensive Assessment Reports (AR): AR1 (1990), AR2 (1995), AR3 (2001), AR4 (2007), AR5 (2014), and AR6 (2021‑2022). AR4 famously introduced the term “global warming of 2 °C” as a policy threshold, while AR5 quantified a 1.5 °C warming as a “dangerous” level with a 50 % probability of exceeding it within the next two decades. AR6, published in three volumes between August 2021 and March 2022, reaffirmed that human influence is “unequivocal” and that limiting warming to 1.5 °C would require net‑zero CO₂ emissions by around 2050. In addition to the full assessments, the panel issues Special Reports on urgent topics. SR1 (2019) on “Global Warming of 1.5 °C” informed the 2015 Paris Agreement’s ambition clause; SRCCL (2022) examined land‑use change and its climate implications; and SROCC (2022) addressed oceanic and cryospheric changes. Each Special Report follows the same rigorous review protocol but is produced in a compressed timeframe of 18‑24 months. ## Influence on International Climate Policy The IPCC’s assessments have directly shaped the architecture of global climate governance. The 1992 United Nations Framework Convention on Climate Change (UNFCCC) cites the panel’s scientific findings as the basis for “common but differentiated responsibilities.” The Kyoto Protocol’s binding emission targets were calibrated using AR2 and AR3 data, while the Paris Agreement’s nationally determined contributions (NDCs) rely on the mitigation pathways outlined in AR5 and AR6. Beyond treaty texts, the IPCC informs national climate strategies, financial mechanisms, and sectoral regulations. For instance, the European Union’s “Fit for 55” package references AR6’s carbon budget estimates, and the United States’ Inflation Reduction Act’s clean‑energy tax credits align with WG III’s cost‑effectiveness analyses. The panel’s credibility—derived from its open‑review process and broad author base—has made its reports the