Coupled Model Intercomparison Project Phase 5

Coupled Model Intercomparison Project Phase 5
Name	Coupled Model Intercomparison Project Phase 5
Abbreviation	CMIP5
Started	2008
Completed	2014
Coordinating body	World Climate Research Programme
Major publication	Fifth Assessment Report

Coupled Model Intercomparison Project Phase 5 was the fifth coordinated ensemble of global climate model experiments organized to support the Intergovernmental Panel on Climate Change Fifth Assessment Report and a broad community of climate researchers. It provided standardized experimental protocols, multi-model archives, and diagnostics used by teams from national laboratories, universities, and international agencies to assess model performance, projections, and uncertainties. The project influenced assessments by the Intergovernmental Panel on Climate Change, informed policy processes such as United Nations Framework Convention on Climate Change negotiations, and underpinned numerous peer-reviewed studies.

Overview

CMIP5 built on earlier phases coordinated by the World Climate Research Programme and linked to programs including the International Geosphere-Biosphere Programme, the Climate and Cryosphere Project, and the Global Carbon Project. It involved model groups from agencies such as National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, Met Office Hadley Centre, Max Planck Institute for Meteorology, Commonwealth Scientific and Industrial Research Organisation, Geophysical Fluid Dynamics Laboratory, and universities including Princeton University, University of Oxford, Massachusetts Institute of Technology, and Potsdam Institute for Climate Impact Research. Outputs were essential to chapters in the Fifth Assessment Report and to initiatives like the Task Force on National Greenhouse Gas Inventories and the Global Framework for Climate Services.

Experimental Design and Protocols

The CMIP5 experimental framework specified historical simulations, idealized experiments, and future scenarios defined by Representative Concentration Pathways used by the Intergovernmental Panel on Climate Change authors. Protocols required model runs for periods spanning preindustrial control, historical (1850–2005), and future projections (2006–2100) under scenarios such as RCP2.6, RCP4.5, RCP6.0, and RCP8.5. Experiments included decadal prediction setups influenced by methodologies from the European Centre for Medium-Range Weather Forecasts, initialized ocean–atmosphere systems championed by groups like NOAA Geophysical Fluid Dynamics Laboratory, and sensitivity tests following guidance from the World Climate Research Programme’s Working Group on Coupled Modelling. Standardized output conventions adopted practices from the Earth System Grid Federation and the Program for Climate Model Diagnosis and Intercomparison.

Participating Models and Institutions

Hundreds of model realizations came from modeling centers including NASA Goddard Institute for Space Studies, National Center for Atmospheric Research, Canadian Centre for Climate Modelling and Analysis, Meteorological Research Institute (Japan), Institute Pierre-Simon Laplace, Los Alamos National Laboratory, Tokyo Institute of Technology, and University of Washington. Model families encompassed atmosphere–ocean coupled systems, Earth system models with interactive carbon cycles developed at Lawrence Livermore National Laboratory and Centre National de Recherches Météorologiques, and regional downscaling experiments by groups such as International Centre for Theoretical Physics and Barcelona Supercomputing Center. Collaborative efforts included data curation by the Earth System Grid Federation and diagnostics provided by the Climate Model Intercomparison Project community and researchers affiliated with Imperial College London and the Swiss Federal Institute of Technology in Zurich.

Key Findings and Assessments

CMIP5 ensembles clarified ranges of climate sensitivity, transient climate response, and projected surface temperature and precipitation changes underpinning conclusions in the Fifth Assessment Report. Analyses quantified uncertainties arising from scenario choice, model formulation, and internal variability, with region-specific assessments for areas studied by teams at Columbia University, University of East Anglia, Stockholm University, and Australian National University. Results informed assessments of sea level rise synthesised with work by National Aeronautics and Space Administration and European Space Agency, informed projections of Arctic sea ice loss examined by groups at University of Alaska Fairbanks and University Centre in Svalbard, and advanced understanding of carbon cycle feedbacks investigated by the Global Carbon Project and International Geosphere-Biosphere Programme researchers.

Data Access and Archival Resources

CMIP5 data were archived and distributed via the Earth System Grid Federation portals hosted by centers including NCAR, PCMDI, ESGF Data Nodes, and computing facilities at Lawrence Berkeley National Laboratory and Argonne National Laboratory. Metadata and standardized file formats followed NetCDF conventions and Climate and Forecast (CF) metadata guidelines used by the Program for Climate Model Diagnosis and Intercomparison. The archive supported reproducible research by enabling cross-model diagnostics by teams at Princeton University, California Institute of Technology, University of Cambridge, and repositories linked to Digital Object Identifier assignment practices.

Impact on Climate Science and Policy

CMIP5 underpinned scientific chapters in the Fifth Assessment Report and provided evidence cited in policy fora such as Conference of the Parties to the United Nations Framework Convention on Climate Change sessions and technical inputs to the Intergovernmental Panel on Climate Change's policy-relevant assessments. The multi-model ensemble influenced adaptation planning in agencies including United States Environmental Protection Agency, national meteorological services such as the Met Office, and international programs like the World Meteorological Organization’s regional climate initiatives. CMIP5 also shaped methodological advances adopted in subsequent coordinated efforts led by the World Climate Research Programme and motivated community projects involving the European Union research funding mechanisms and national science agencies.

Category:Climate modelling