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 climate of the Pre-industrial control experimen t (picntrl). These datasets are available in netCDF and GRIB format. The initial condition is taken from the final state of a 450 year "pre-industrial spin-up (PIspup)" which initiated from the end of "present-day spin-up" run. The forcing of the PIspup and PIcntrl experiments includes greenhouse gases, sulfate aerosol (natural source only) direct effects and solar forcing, and is fixed at levels of year 1850. For this experiment there is only one run available. For model output data in higher temporal resulution and more variables visit the web page https://esg.llnl.gov:8443/home/publicHomePage.do.