From its origins as a punctuated phasing of a few key coupled atmosphere–ocean general circulation model experiments, the Coupled Model Intercomparison Project (CMIP) has evolved into a continuous climate Earth system modelling programme supported by design of experimental protocol, forcing dataset development, infrastructure solutions, and format requirements. These defined phases tackle key and timely climate science questions and facilitate delivery of relevant multi-model simulations through shared infrastructure for the benefit of the climate research community, climate impact and adaptation practitioners, national and international climate assessments, and society at large. In a series of invited contributions, this special issue describes the evolving design and organization of CMIP, the suite of experiments of its seventh phase (CMIP7) including the new AR7 Fast Track component and registered model intercomparison projects (MIPs) adhering to CMIP data standards and best-practice experimental protocol and data requests, and enabling infrastructure. The papers provide the required information to produce a consistent set of climate model simulations that can be scientifically exploited to support the World Climate Research Programme (WCRP) science priorities, which currently include Fundamental understanding of the climate system, Prediction of the near-term evolution of the climate system, Long-term response of the climate system, and Bridging climate science and society, and future climate assessments informing policy and decision-making. A separate GMD special issue is providing an overview of the various CMIP7 forcings.

Review process: all papers of this special issue underwent the regular interactive peer-review process of Geoscientific Model Development handled by members of the GMD editorial board.