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 1%/year CO2 increase experiment (to quadrupling). _ These datasets are available in netCDF and GRIB format. _ For this experiment there is only one run available. _ Model output data for CMIP3 in higher temporal resolutions and further variables are available in ESGF at https://esgf-node.llnl.gov/search/cmip3/.