Changes in global stratospheric ozone

The current state of knowledge of trends in ozone is reviewed. Recent analyses have confirmed the general features of stratospheric ozone reported previously. There is several depletion over Antarctica each Austral spring, periodic large losses over the Arctic in Boreal spring and smaller long-term decreases over the heavily mid-latitudes. There are no statistically significant trends over the tropics. Both changes in chemical composition, particularly chlorine and bromine amounts, and changes in atmospheric dynamics have influenced the ozone changes over the last decades. The importance and difficulty of accurately attributing the observed changes to these two causes is discussed.