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. These datasets are available in netCDF and GRIB format. For this experiment there are 3 ensemble runs available. This model run continues from the end of the 20th century simulation with GHG and aerosol loadings for the IPCC SRES A1B scenario as tabulated in the IPCC Third Assessment Report, Appendix II. The CO2 concentrations are from the Bern-CC model (Contribution of Working Group I to the Third Assesment Report of IPCC, p808) and the aerosol loadings are from O. Boucher, Laboratoire d`Optique Atmospherique, France. For years 2101-2300, all GHG concentrations and the aerosol loading are held constant at the values obtained by extrapolation to year 2101. For model output data in higher temporal resulution and more variables visit the web page https://esg.llnl.gov:8443/home/publicHomePage.do.