A Summary of the CMIP5 Experiment Design

At a September 2008 meeting involving 20 climate modeling groups from around the world (i.e., most of the major groups performing climate change research today), the WCRP’s Working Group on Coupled Modelling (WGCM), with input from IGBP’s AIMES, agreed on a new set of coordinated climate model experiments, to be known as phase five of the Coupled Model Intercomparison Project (CMIP5). The purpose of these experiments is to address outstanding scientific questions that arose as part of the IPCC AR4 assessment process, improve understanding of climate, and to provide estimates of future climate change that will be useful to those considering its possible consequences. As in past CMIP phases, results from this new set of simulations is expected to lead to climate information and knowledge of particular relevance to future international assessments of climate science (e.g., the IPCC’s AR5, now scheduled to be published in 2013). Consequently, for the compelling science motivations and for the interest in the IPCC AR5, the CMIP5 simulations will become a high priority on the research agendas of most major climate modeling centers. CMIP5 is meant to provide a framework for coordinated climate change experiments for about the next five years and thus includes simulations for assessment in the AR5 as well as others that extend beyond the AR5. CMIP5 is not, however, meant to be comprehensive; it cannot possibly include all the different model intercomparison activities that might be of value, and it is expected that various groups and interested parties will develop additional experiments that might build on and augment the experiments described here. In the IPCC assessment context, it is expected that CMIP5 will provide information of value to all three IPCC Working Groups.