Ozone soundings at middle and high latitudes of the Northern Hemisphere during recent decades indicate a decreasing trend in the lower stratosphere and an increasing trend in the troposphere especially at the upper troposphere. Changes in the O3 vertical distribution can change the radiative forcing (solar and longwave radiation) to the troposphere-surface system with climate implications. here, we use the O3 soundings at seven middle and high latitudes stations to study its variations in the last few decades and discuss the climate implications in the context of increasing other greenhouse gases CO2, CH4, CFC-11, CFC-12, and N2O. The results suggest that changes in O3 vertical distribution can perturb substantially the radiative forcing, in particular at the middle latitudes where the tropospheric increases can induce a positive radiative forcing (warming) with magnitude comparable to that due to increasing these other greenhouse gases. ¿ American Geophysical Union 1993