No one had any idea that these chemicals could travel to the stratosphere and react with ozone. This treaty was the first international environmental treaty. For several years we have been measuring declining quantities of ozone depleting chemicals in the trophosphere. Because we know that ozone depleting chemicals must move from the surface of the planet through the troposphere before reaching the stratosphere, the declining levels observed in the troposphere tell us that the levels to be expected in the stratosphere are lower than in the recent past. The level of ozone depletion will not reach the originally predicted, incredibly dangerous, levels.
Ozone depletion follows a seasonal cycle.
In the June a vortex concentrates ozone depletion chemicals over Antarctica. Clouds form during the winter providing a surface for CFCs and other ozone depletion chemical to react resulting in the formation of Cl2, etc. The Cl- ions react with ozone, thus forming ClO, and stratospheric ozone concentrations decline. In the summer and fall, there are no stratospheric clouds, NO2, and CH4 react with ClO, and ozone levels increase but do not return to the previous summer's level. Explain the process of global warming.