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 4 ensemble runs available. This simulation was initiated from year 1980-03 of PCM1 model run B06.08 and executed on hardware cheetah.ccs.ornl.gov. The input external forcings are: "ozone forcing : noaao3.122yr.IPCC.041299.nc, "solar forcing : Hoyt/Schatten solar forcing, defined in code, " : see website for details, "GHGs : defined in code, see website, "volcanic forcing : none, "SOx emissions : SO4-A1.1980-2099.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 For model output data in higher temporal resulution and more variables visit the web page https://esg.llnl.gov:8443/home/publicHomePage.do.