These data represent monthly averaged values of selected variables for the Data Distribution Centre (DDC) of the Intergovernmental Panel on Climate Change (IPCC). (see also http://www.ipcc-data.org/) The model output prepared for IPCC Fourth Assessment committed climate change experiment (COMMIT). These datasets are available in netCDF and GRIB format. For this experiment there is only one run available. Commitment experiment with CSIRO Mk 3.0 model, starting from year 2000 (model year 250) of 20C3M experiment. Radiative forcings held constant at year 2000 values for entire experiment. Model output data for CMIP3 in higher temporal resolutions and further variables are available in ESGF at https://esgf-node.llnl.gov/search/cmip3/.