How much has ozone been depleted over Australia?
Ozone depletion in the 1980s and early 1990s was more severe in the southern hemisphere than the northern. Observations suggest that, in southern mid-latitudes (which includes Sydney, Canberra, Adelaide, Melbourne and Hobart) the amount of depletion caused by ODSs during this time was about 5%. The amount of depletion was observed to be smallest in the tropics and to increase with distance from the equator. It is important to remember, though, that total ozone varies considerably from year to year due to natural variations, not all of which are currently fully accounted for. This means that it takes many years for clear trends to be discernible. Further long-term ozone changes can be caused by changes in transport rather than chemistry. Nonetheless, there are now tentative early indications that ozone is recovering following the success of the Montreal Protocol and its amendments.
