Intergovernmental Panel on Climate Change (IPCC)

The World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) created the IPCC in 1988, and the UN General Assembly endorsed it later that year.^1,2,3 It is an organization of governments with 195 member countries.^1,2 Its purpose is to give governments at all levels scientific information they can use to develop climate policy, and its reports feed into international climate negotiations.² The secretariat is in Geneva, hosted by the WMO.⁴

The IPCC does not conduct its own research.^1,2 Experts volunteer as authors to assess the thousands of scientific papers published each year. They summarise what is known about the drivers of climate change, its impacts and future risks, and how adaptation and mitigation can reduce those risks.² Drafts are reviewed by experts and governments.² The reports are meant to be policy-relevant but not policy-prescriptive.¹ The work is split among three working groups. The first assesses the physical science basis of climate change. The second deals with the impacts of climate change, vulnerability to them and adaptation. The third deals with mitigation.² A Task Force on National Greenhouse Gas Inventories develops the method countries use to calculate and report their emissions and removals.²

Since 1988 the IPCC has had six assessment cycles and delivered six Assessment Reports.³ The first, in 1990, played a decisive role in the creation of the UN Framework Convention on Climate Change. The fifth, finalised in 2013 and 2014, gave the scientific input to the Paris Agreement, and the sixth was finalised in March 2023.³ A cycle usually runs six to seven years.⁴ The seventh began in July 2023 with the election of a new Chair and Bureaus.⁵ At its first session of the cycle, in Istanbul in January 2024, the Panel agreed to produce the three Working Group reports, with a Synthesis Report to follow by late 2029.⁵ Also planned are a Special Report on Climate Change and Cities, listed for March 2027, and methodology reports on short-lived climate forcers and on carbon dioxide removal, both listed for December 2027.^5,6 The Panel decided on the cities report in 2016 and agreed its outline in 2024. All three working groups lead it jointly.⁷

The Working Group I volume of the sixth report closes with an Atlas chapter on observed and projected change in regional climate.⁸ It uses model simulations from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP5 and CMIP6) and regional runs from the Coordinated Regional Climate Downscaling Experiment (CORDEX).⁸ A 2026 paper on this site ranks the CMIP6 models sector by sector.

The chapter comes with an online tool, the Interactive Atlas (interactive-atlas.ipcc.ch).^8,9 It maps observed trends and projected changes in temperature, precipitation, extreme indices and climatic impact-drivers. Projections are given for near, medium and long-term periods under emissions scenarios, and for global warming levels of 1.5, 2, 3 and 4 °C.⁸ Clicking on one or more regions brings up charts and tables of values averaged over each region, such as time series and annual cycles.⁸ The reference grids are 1° and 2°, the typical resolutions of CMIP6 and CMIP5 models.⁸ Images export as PNG or PDF, and the data behind the global maps download as NetCDF or GeoTIFF with provenance metadata.⁸ The scripts behind most of the chapter's figures are public at github.com/IPCC-WG1/Atlas.⁸ For someone modelling a city or a watershed, the atlas is a way to take the assessed regional projections, and the spread between models, as an input without running a climate model.