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 SRES A2 experiment. These datasets are available in netCDF and GRIB format. This simulation was initiated from year 2000 of CCSM3 model run b30.030a and executed on hardware seaborg.nersc.gov. The input external forcings are ozone forcing : A2.ozone.128x64_L18_1991-2100_c040528.nc aerosol optics : AerosolOptics_c040105.nc aerosol MMR : AerosolMass_V_128x256_clim_c031022.nc carbon scaling : carbonscaling_1870-2000_c040225.nc solar forcing : Fixed at 1366.5 W m-2 GHGs : ghg_ipcc_A2_1870-2100_c040521.nc GHG loss rates : noaamisc.r8.nc volcanic forcing : none DMS emissions : DMS_emissions_128x256_clim_c040122.nc oxidants : oxid_128x256_L26_clim_c040112.nc SOx emissions : SOx_emissions_A2_128x256_L2_1990-2100_c040608.nc Integrations were performed by NCAR and CRIEPI with support and facilities provided by NSF, DOE, MEXT and ESC/JAMSTEC. For this experiment there are 5 ensemble runs available. For model output data in higher temporal resulution and more variables visit the web page https://esg.llnl.gov:8443/home/publicHomePage.do.