An evolving Coupled Model Intercomparison Project phase 7 (CMIP7) and Fast Track in support of future climate assessment

Abstract. The vision for the Coupled Model Intercomparison Project (CMIP) is to coordinate community based efforts to answer key and timely climate science questions and facilitate delivery of relevant multi-model simulations through shared infrastructure for the benefit of the physical understanding, vulnerability, impacts and adaptations analysis, national and international climate assessments, and society at large. From its origins as a punctuated phasing of climate model intercomparison and evaluation, CMIP is now evolving through coordinated and federated planning into a more continuous climate modelling programme. The activity is supported by the design of experimental protocols, an infrastructure that supports data publication and access, and the phased delivery or “fast track” of climate information for national and international climate assessments informing decision making. Key to these CMIP7 efforts are: an expansion of the Diagnostic, Evaluation and Characterization of Klima (DECK) to include historical, effective radiative forcing, and focus on CO₂-emissions-driven experiments; sustained support for community MIPs; periodic updating of historical forcings and diagnostics requests; and a collection of experiments drawn from community MIPs to support research towards the 7th Intergovernmental Panel on Climate Change Assessment Reporting cycle, or “AR7 Fast Track”, and climate services goals across prediction and projection, characterization, attribution and process understanding.