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. This simulation was initiated from year 0140-03 of PCM1 model run B04.10 and executed on hardware nirvana.acl.lanl.gov. The input external forcings are ozone forcing : ozn.T42.0596, cycled solar forcing : Fixed 1367.0 W m-2 GHGs : CO2 only increases 1% per year volcanic forcing : none SOx emissions : sulfate_1985ab.nc, scaled in code and cycled 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 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/.