Dramatic loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s by a research group who were
monitoring the atmosphere above Antarctica from a research station much like the picture to the right.
Folklore has it that when the first measurements were taken in 1985, the drop in ozone levels in the
stratosphere was so dramatic that at first the scientists thought their instruments were faulty. Replacement instruments were built and flown out, and it wasn't until they confirmed the earlier measurements, several months later, that the ozone depletion observed was accepted as genuine.
Another story goes that the TOMS satellite data didn't show the dramatic loss of ozone because the software processing the raw ozone data from the satellite was programmed to treat very low values of ozone as bad readings! Later analysis of the raw data when the results from the British Antarctic Survey team were published, confirmed their results and showed that the loss was rapid and large-scale; over most of the Antarctica continent.
Over Antarctica ( and recently over Arctic ), stratospheric ozone has been depleted over the last 15 years at certain times of the year. This is mainly due to the release of manmade chemicals containing chlorine such as CFC's ( Chloro Fluoro Carbons ) but also
compounds containing bromine, other related halogen compounds and also nitrogen oxides (NOx). CFC's are a common industrial product, used in refrigeration systems, air conditioners, aerosols, solvents and in the production of some types of packaging. Nitrogen oxides are a by-product of combustion processes, eg aircraft emissions.
The current levels of depletion have served to highlight a surprising degree of instability of the atmosphere, and the amount of ozone loss is still increasing. GreenPeace have documented many of the concerns it raises that this raises.
What Is Being Done?
The first global
agreement to restrict CFCs came with the signing of the Montreal Protocol in 1987 ultimately aiming to reduce them by half by the year 2000. Two revisions of this agreement have been made in the light of advances in scientific understanding, the latest being in 1992. Agreement has been reached on the control of industrial production of many halocarbons until the year 2030. The main CFCs will not be produced by any of the signatories after the end of 1995, except for a limited amount for essential uses, such as for medical sprays.
The countries of the European Community have adopted even stricter measures than are required under the Montreal Protocol agreements. Recognising their responsibility to the global environment they have agreed to halt production of the main CFCs from the beginning of 1995. Tighter deadlines for use of the other ozone-depleting compounds are also being adopted.
It was anticipated that these limitations would lead to a recovery of the ozone layer within 50 years of 2000; the World Meterological Organisation estimated 2045 , but recent investigations suggest the problem is perhaps on a much larger scale than anticipated