The retreat of glaciers in Iceland due to climate warming during the last century has resulted in changed hydrological conditions at glacial margins and in larger sandy areas. Subsequently, aeolian processes have become more active. The aim of this research was to study wind erosion south of Langjökull glacier and the development of encroaching sand, as well as the influence of macro and micro topography on the processes. Automatic instruments and aeolian dust traps were used to monitor wind erosion and to estimate its dependence on surface roughness. Digital elevation model was used to analyse the effect of macro topography on sand encroachment. The study indicates that large quantities of sand have moved southwards from the glacial moraine and drained lakes. The spatial distribution of the sand confirms a dominating aeolian transportation by northerly dry winds. The topography influences wind directions and the flux of aeolian materials. Threshold velocities (wind speed measured at 2 m height) ranged from 6·2 m s−1 on level land to 10·7 m s−1 on rough surfaces. Flux can exceed 1000 kg m−1 hr−1 at 17 m s−1 wind speed. Slopes exceeding 7 per cent reduce or halt sand movement. Rough surfaces immobilize the aeolian material until accumulated material has leveled the surface, after that the flux continues. The intensified aeolian processes have buried previously vegetated areas and it is likely that continued glacier retreat due to climate warming will cause further land degradation in this area. Copyright © 2005 John Wiley & Sons, Ltd.