Reduced Complexity Model Intercomparison Project phase 3: experimental protocol for coordinated constraining and evaluation of reduced-complexity models
Abstract. Reduced-Complexity Models (RCMs) are a critical tool for synthesising climate science knowledge and providing climate projections for a wide range of emissions scenarios. The Reduced-Complexity Model Intercomparison Project (RCMIP) provides a framework for the coordinated evaluation and application of these models. Here, we introduce the experimental protocol for RCMIP Phase 3 (RCMIP3), which is timed to inform the upcoming seventh assessment cycle of the Intergovernmental Panel on Climate Change (IPCC AR7). Taking stock of lessons from previous phases, RCMIP3 builds on community climate assessment products to support a common framework to compare RCM output against historical climate benchmarks. The experimental design aims to support a comprehensive assessment of RCMs across multiple climate-relevant domains, with a particular focus on carbon cycle dynamics and climate reversibility. The protocol is designed in tandem with the Coupled Model Intercomparison Project Phase 7 (CMIP7), replicating its “Assessment Fast Track” together with complementary experiments which explore wider state dependencies, sampling multiple scenario generations, long timescale response and diverse emissions-driven process representation.
Authors
- Benjamin Mark Sanderson (ORCID: https://orcid.org/0000-0001-8635-4624)
- Chris Smith (ORCID: https://orcid.org/0000-0003-0599-4633)
- Norman Julius Steinert (ORCID: https://orcid.org/0000-0002-2154-5857)
- Katsumasa Tanaka (ORCID: https://orcid.org/0000-0001-9601-6442)
- Jarmo Kikstra (ORCID: https://orcid.org/0000-0001-9405-1228)
- Camilla Mathison (ORCID: https://orcid.org/0000-0002-6269-4605)
- Zebedee Nicholls (ORCID: https://orcid.org/0000-0002-4767-2723)
- Marit Sandstad (ORCID: https://orcid.org/0009-0007-2329-694X)
- Thomas Gasser (ORCID: https://orcid.org/0000-0003-4882-2647)
- K. Weber (ORCID: https://orcid.org/0009-0003-5230-0283)
- Alejandro Romero-Prieto (ORCID: https://orcid.org/0009-0005-8522-7697)
- Thomas J. Aubry (ORCID: https://orcid.org/0000-0002-9275-4293)
Institutions
- Met Office (GB)
- Centre National de la Recherche Scientifique (FR)
- University of Leeds (GB)
- International Institute for Applied Systems Analysis (AT)
- The University of Melbourne (AU)
- Université de Versailles Saint-Quentin-en-Yvelines (FR)
- National Institute for Environmental Studies (JP)
- University of Exeter (GB)
- Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR)
- Université Paris-Saclay (FR)
- ETH Zurich (CH)
- University of Oxford (GB)
- Institute for Biomedical Engineering (CH)
- CICERO Center for International Climate Research (NO)
- Climate Analytics (DE)
- Laboratoire des Sciences du Climat et de l'Environnement (FR)
- CEA Paris-Saclay (FR)
Publication Details
- Journal
- Geoscientific model development
- Published
- 2026-08-03
- DOI
- https://doi.org/10.5194/gmd-19-7111-2026
- Primary Topic
- Sustainability and Climate Change Governance
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Government of the United Kingdom
- UK Research and Innovation
- European Space Agency
- European Commission
- Met Office
- Norges Forskningsråd
- HORIZON EUROPE Framework Programme
- Natural Environment Research Council
- Horizon 2020