Results are presented for two greenhouse gas experiments of the Goddard Institute for Space Studies Atmosphere-Ocean Model (AOM). The computed trends of surface pressure, surface temperature, 850, 500 and 200 mb geopotential heights and related temperatures of the model for the time frame 1960-2000 are compared to those obtained from the National Centers for Environmental Prediction (NCEP) reanalysis. The domain of interest is the Northern Hemisphere (NH) because of the higher reliability of both the model results and the reanalysis. A spatial correlation analysis and mean value comparison are performed, showing good agreement in terms of statistical significance for most of the variables considered in the winter and in the annual means. The accuracy that this AOM has in describing through the atmosphere the regional and NH mean climate trends inferred from NCEP suggests that it may be reliable in forecasting future climate changes.