| Abstract |
CMIP, the Coupled Model Intercomparison Project, is the analog of AMIP for global coupled ocean-atmosphere general circulation models. CMIP began in 1995 under the auspices of the Numerical Experimentation Group 2 (NEG-2) of CLIVAR. The PCMDI supports CMIP in much the same way that it supports AMIP: by helping NEG-2 to determine the scope of the project, by maintaining the project's data base, and by participating in data analysis. At present, CMIP is a "Level 1" intercomparison, using model output that was produced with boundary conditions, initial conditions and spin-up procedures that differ somewhat from model to model. Later phases of CMIP may involve "Level 2" intercomparisons like AMIP.
The purpose of CMIP is to examine climate variability and predictability as simulated by the models, and to compare the model output with observations where available. Coupled ocean-atmosphere GCMs are used to predict future global changes, such as warming due to anthropogenic greenhouse gases (Houghton et al., 1996). In addition, coupled-GCM simulations of the natural climate (without human interference) can be compared with observations over the past century. Recent work along such lines concludes that an anthropogenic signal of global warming is emerging from natural variability "noise" (ibid.). More careful and systematic examination of the models thus seems warranted.
CMIP began in 1995 under the auspices of the Working Group on Coupled Models (WGCM) of CLIVAR. The PCMDI supports CMIP in much the same way that it supports AMIP: by helping WGCM to determine the scope of the project, by maintaining the project's data base, and by participating in data analysis.
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