Radar observations of mesosphere/lower thermosphere (MLT) monthly mean winds are analysed with respect to long-term trends and their changes between 1980 and 2015. Zonal prevailing winds are generally increasing with time, but there is a tendency for a change in trend in the 1990s. This is also visible in the meridional wind, which increases in the 1980s but decreases in more recent years. Numerical experiments with a mechanistic global circulation model with nudged tropospheric and lower stratospheric temperatures are performed that show the respective effect of continuous CO₂ increase and stratospheric ozone decrease, and the turnaround of ozone changes in the 1990s. It is also shown that the MLT dynamics and trends in the model strongly depend on the assimilated lower atmosphere data, while the summer trends are more determined by middle atmosphere trace gas changes.