CMIP5 - Coupled Model Intercomparison Project Phase 5 - Overview
At a September 2008 meeting involving 20 climate modeling groups from around the world, the WCRP’s Working Group on Coupled Modelling (WGCM), with input from the IGBP AIMES project, agreed to promote a new set of coordinated climate model experiments. These experiments comprise the fifth phase of the Coupled Model Intercomparison Project (CMIP5). CMIP5 will notably provide a multi-model context for 1) assessing the mechanisms responsible for model differences in poorly understood feedbacks associated with the carbon cycle and with clouds, 2) examining climate “predictability” and exploring the ability of models to predict climate on decadal time scales, and, more generally, 3) determining why similarly forced models produce a range of responses.
It is expected that some of the scientific questions that arose during preparation of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) will through CMIP5 be addressed in time for evaluation in the Fifth Assessment Report (AR5, scheduled for publication in late 2013). The IPCC/CMIP5 schedule (pdf) is now available and the three key dates are as follows:
- February 2011: First model output is expected to be available for analysis,
- July 31, 2012: By this date papers must be submitted for publication to be eligible for assesment by WG1,
- March 15, 2013: By this date papers cited by WG1 must be published or accepted.
The IPCC’s AR5 was published in September 2013. Future timeline information can be found on IPCC WG1 website.
CMIP5 is meant to provide a framework for coordinated climate change experiments for 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.
CMIP5 promotes a standard set of model simulations in order to:
- Evaluate how realistic the models are in simulating the recent past
- Provide projections of future climate change on two time scales, near term (out to about 2035) and long term (out to 2100 and beyond)
- And to understand some of the factors responsible for differences in model projections, including quantifying some key feedbacks such as those involving clouds and the carbon cycle
The CMIP5 (CMIP Phase 5) experiment design has been finalized with the following suites of experiments:
- Decadal Hindcasts and Predictions simulations,
- “long-term” simulations,
- “atmosphere-only” (prescribed SST) simulations for especially computationally-demanding models.