The geographical distribution and the seasonal variability of soil dust aerosol have been investigated with the climate model ECHAM4. Two experiments have been performed: a climatological with prescribed climatological sea surface temperatures (CLIM) and a nudged where the model is forced by ECMWF Reanalysis data of the particular years 1986--1991 (NUDGE). The mean geographical distribution and the seasonal variability of mineral dust alter between the different modes of operation of the climate model. Largest deviations occur in Northern Hemisphere winter and are related to the overestimation and the mislocation of the Azores high in ECHAM4. The Saharan dust plume is shifted farther north in CLIM compared to NUDGE and Meteosat satellite observations with significant implication for the cross-Atlantic transport. In the dust source regions the wind speed distribution is slightly shifted and creates a twofold difference in total dust emissions. Our results indicate that the mode of operation of the climate model seems to be as important as the interannual variability of the dust cloud by climate variations alone.