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 A1B experiment. For this experiment there are 7 ensemble runs available. This simulation was initiated from year 2000 of, CCSM3 model run b30.030a and executed on, hardware cheetah.ccs.ornl.gov. The input external forcings are, "ozone forcing : A1B.ozone.128x64_L18_1991-2100_c040528.nc, "aerosol optics : AerosolOptics_c040105.nc, "aerosol MMR : AerosolMass_V_128x256_clim_c031022.nc, "carbon scaling : carbonscaling_A1B_1990-2100_c040609.nc, "solar forcing : Fixed at 1366.5 W m-2, "GHGs : ghg_ipcc_A1B_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_A1B_128x256_L2_1990-2100_c040608.nc, " Physical constants used for derived data:, " Lv (latent heat of evaporation): 2.501e6 J kg-1, " Lf (latent heat of fusion ): 3.337e5 J kg-1, " r[h2o] (density of water ): 1000 kg m-3, " g2kg (grams to kilograms ): 1000 g kg-1, Integrations were performed by NCAR and CRIEPI with support, and facilities provided by NSF, DOE, MEXT and ESC/JAMSTEC. For model output data in higher temporal resulution and more variables visit the web page https://esg.llnl.gov:8443/home/publicHomePage.do.