The Coupled Model Intercomparison Project

 

All models used to project climate have some uncertainty associated with them, owing to approximations that must be made in representing certain physical processes. To understand the uncertainty in models, scientists compare them with other models and evaluate how much the models differ in their projections. To determine this, an ensemble of models is needed, allowing a range of simulations and projections to be analyzed and compared. The World Climate Research Programme has established the Coupled Model Intercomparison Project (CMIP) specifically for this purpose. An agreed-upon suite of historical simulations and future climate projections are performed using the same external forcing (changing GHGs, land-use, etc.). The outputs from the models are archived in a common format for analysis by the climate research community (Taylor et al., 2012). Previous versions of CMIP have provided model results assessed in earlier IPCC Assessment Reports. The most recent, fifth phase of this project, CMIP5, provided climate model results that were assessed in the IPCC Fifth Assessment Report (IPCC, 2013), and many of these results are available from the Canadian Climate Data and Scenarios website. Future climate projections in CMIP5 used the Representative Concentration Pathways emission scenarios (see Section 3.2) (van Vuuren et al., 2011). A new version, CMIP6, is currently underway and will serve as input to the IPCC Sixth Assessment.