How much more ozone depletion will occur?
No one knows for certain. Even if all nations meet their international commitments to phase out ozone-depleting substances, the levels of these chemicals in the stratosphere will remain near peak values for the next 10 to 20 years. To the late 1990’s, the ozone layer over southern Canada thinned by an average of about 6 per cent. There is some concern that radiative effects of increased greenhouse gas concentrations may result in delayed ozone layer recovery. Eventually, however, a slow recovery is expected to begin, with a return to pre-1980 values after the mid-portion of the twenty-first century. It is important to note that scientific knowledge of the atmosphere and the processes that deplete the ozone layer is not complete. The sudden and unexpected appearance of the Antarctic ozone hole reveals that the ozone layer does not respond predictably to the quantities of industrial chemicals we are dumping into it.
No one knows for certain. Even if all nations meet their international commitments to phase out ozone-depleting substances, the levels of these chemicals in the stratosphere will remain near peak values for the next 10 to 20 years. To the late 1990’s, the ozone layer over southern Canada thinned by an average of about 6 per cent. There is some concern that radiative effects of increased greenhouse gas concentrations may result in delayed ozone layer recovery. Eventually, however, a slow recovery is expected to begin, with a return to pre-1980 values after the mid-portion of the twenty-first century. It is important to note that scientific knowledge of the atmosphere and the processes that deplete the ozone layer is not complete. The sudden and unexpected appearance of the Antarctic ozone hole reveals that the ozone layer does not respond predictably to the quantities of industrial chemicals we are dumping into it.
