CMIP3

CMIP3
Name	CMIP3
Full name	Coupled Model Intercomparison Project Phase 3
Started	2004
Coordinated by	World Climate Research Programme; Intergovernmental Panel on Climate Change
Purpose	climate model intercomparison for Fourth Assessment Report
Participants	multiple international modeling centres
Successor	Coupled Model Intercomparison Project Phase 5

CMIP3 CMIP3 was the third phase of the Coupled Model Intercomparison Project organized to coordinate climate model experiments for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. It provided a standardized framework for multi-model simulations across leading institutions such as Hadley Centre, National Center for Atmospheric Research, Max Planck Institute for Meteorology, and Geophysical Fluid Dynamics Laboratory. CMIP3 outputs underpinned assessments by panels and working groups including IPCC Working Group I and influenced policymakers at venues like the United Nations Framework Convention on Climate Change.

Overview

CMIP3 assembled coupled atmosphere–ocean general circulation models from centres including Meteorological Research Institute, Canadian Centre for Climate Modelling and Analysis, CSIRO, Australian Bureau of Meteorology Research Centre, and Institute Pierre-Simon Laplace. It established standardized experiments drawing on forcing datasets tied to scenarios by Special Report on Emissions Scenarios and coordinated by World Climate Research Programme task forces. Outputs fed assessments by organizations such as National Aeronautics and Space Administration, European Centre for Medium-Range Weather Forecasts, National Oceanic and Atmospheric Administration, and United States Global Change Research Program.

Participating Models and Institutions

Major modelling groups contributed models including HadCM3, GFDL CM2, NCAR CCSM3, ECHAM5/MPI-OM, MIROC, MRI CGCM, CNRM CM3, and GISS ModelE. Institutions represented included Met Office Hadley Centre, Princeton University, Massachusetts Institute of Technology, Columbia University, University of Oxford, University of Tokyo, Centre National de Recherches Météorologiques, Argonne National Laboratory, Lawrence Livermore National Laboratory, and Scripps Institution of Oceanography. Collaborating projects and centers such as PANGEA, International Geosphere-Biosphere Programme, Global Climate Observing System, and World Data Center for Climate supported data archiving and distribution.

Experimental Design and Forcings

CMIP3 experiments used historical simulations and future projections driven by Special Report on Emissions Scenarios pathways like A2 scenario, B1 scenario, and A1B scenario. Forcings included greenhouse-gas concentrations from datasets compiled by Intergovernmental Panel on Climate Change authors, aerosol inventories informed by Aerosol and Chemical Transport Model studies, solar irradiance reconstructions linked to Royal Society sponsored work, and volcanic forcing series built from analyses by US Geological Survey and Smithsonian Institution. Boundary conditions and observational constraints referenced datasets from International Satellite Cloud Climatology Project, Global Precipitation Climatology Project, CRU TS, and HadCRUT3.

Key Findings and Climate Projections

CMIP3 multimodel ensembles projected twenty-first-century warming patterns consistent with paleoclimate evidence used by PAGES, showing amplified warming in high latitudes such as over Arctic Ocean regions and changes in precipitation over basins including the Amazon River, Mekong River, and Mississippi River. Projections indicated increases in global mean surface temperature under A2 scenario and A1B scenario with implications for sea-level rise estimates informed by IPCC Working Group II and IPCC Working Group III reports. CMIP3 outputs also explored changes in modes of climate variability including future shifts in El Niño–Southern Oscillation, alterations to the North Atlantic Oscillation, and responses of the Atlantic Meridional Overturning Circulation, informing studies by National Oceanography Centre, Woods Hole Oceanographic Institution, and Lamont–Doherty Earth Observatory.

Evaluation and Model Intercomparison

CMIP3 enabled systematic comparisons across models, assessing performance against observational products from Hadley Centre, NOAA National Climatic Data Center, ECMWF reanalysis, JRA-25, and NCEP/NCAR reanalysis. Intercomparison studies evaluated biases in temperature, precipitation, tropical convection, and sea-ice extent, with diagnostic frameworks developed by groups including PCMDI, CliC, SPARC, and WGCM. Model ranking and emergent constraints were investigated in publications from Nature, Science, Journal of Climate, and Geophysical Research Letters, with contributions from researchers affiliated with University of Reading, Princeton University, University of Colorado Boulder, and University of East Anglia.

Legacy and Influence on Subsequent CMIP Phases

CMIP3 shaped the design of Coupled Model Intercomparison Project Phase 5 and later Phase 6 by demonstrating the value of standardized experiments, archived outputs in portals like the PCMDI Data Archive, and community diagnostics under ESGF infrastructure. Its datasets underpinned policy-relevant assessments by IPCC and informed regional downscaling efforts by institutions such as CORDEX partners and national agencies including NOAA, Met Office, and Environment Canada. Lessons on model diversity, scenario representation, aerosol forcing, and data sharing influenced research programs at European Commission, National Science Foundation, Japan Agency for Marine-Earth Science and Technology, and Deutsches Klimarechenzentrum.

Category:Climate model intercomparison