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 A2 experiment. These datasets are available in netCDF and GRIB format. Initial conditions for this experiment were taken from 1 January 20 1 of the climate of the 20th century experiment named CM2.1U-D4_186-2000-AllForc_H2. Several time varying forcing agents used during t e first 100 years of this CM2.1U-H2_SresA2_W1 experiment were based on output of the MOZART global atmospheric chemistry climate model when driven with the SRES A2 emission scenarios. For the CM2.1U-H2_S esA2_W1 experiment volcanic aerosols were zero, land surface cover types were time invariant, and solar irradiance varied seasonally based upon late 20th century averages but with no interannual variation. 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.