These data represent monthly mean values of selected variables for ENSEMBLES (http://www.ensembles-eu.org). The list of output variables can be found in: http://ensembles.wdc-climate.de/output-variables. The model output was prepared for the ENSEMBLES Stream 2 experiment and comprises the HadGEM2-AO run aiklc (1/12/1999-1/01/2100). The model was initialised from the HadGEM2-AO 20C3M run 1 using 1999 conditions. Anthropogenic forcings (only) were changed through the run to follow values representing the SRES A1B scenario (according to the IMAGE2.2 model), i.e. changes in: CO2, CH4, N2O, CFC11*, CFC12, Ozone, Vegetation Distribution, Sulphur-cycle Emissions, Soot Emissions, Biomass Emissions. No variations were made to solar radiation and volcanic aerosols. (In this experiment CFC11* or equivalent-CFC11 is used to represent other halocarbon gases apart from CFC12). Some model-specific and scenario-specific forcings were needed for this experiment, in particular ship track emissions of sulphate aerosol precursors. Soot and biomass emissions were constructed by re-scaling A1B-IPCC datasets. The vegetation distribution and ozone forcing datasets used are identical to the A1B-IPCC experiments. For composition of dataset names see experiment METO-HC_HADGEM2AO_20C3M_1. For this experiment 1 run was carried out (data relating to aerosol variables is included).