Ozon Hole

Ozone Hole


The influence of the human race on climate is still a matter for study and speculation, but the ability to perturb the ozone layer is an established fact.

The discovery by the British Antarctic Survey of the Antarctic ozone hole provided an early warning of the dangerous thinning of the ozone layer worldwide, and spurred international efforts to curb the production of CFCs. If the provisions of the Montreal Protocol on Substances that Deplete the Ozone Layer of 1987 are revised, strengthened and followed, there is a reasonable prospect that the Antarctic ozone hole will permanently repair itself, but not before the next appearance of Halley's comet! (in the year 2061)

Cover of The Antarctic ozone hole booklet, published by BASBritish scientists began their measurements of Antarctic ozone in 1957. The aim was to understand the important role that ozone plays through absorbing solar energy, in determining the temperature profile of the stratosphere and its wind circulation.

The amount of ozone overhead should follow a regular seasonal pattern. The Antarctic ozone layer did so for the first 20 years of BAS measurements, thereafter clear deviations were observed. In every successive spring the ozone layer was weaker than before, and by 1984 it was clear that the Antarctic stratosphere was changing progressively.

This phenomenon is the result of emissions, mainly in the northern hemisphere, of chlorofluorocarbons (CFCs) and halons. These gases are in widespread use in refrigeration, industrial solvents and fire control. If the provisions of the Montreal Protocol on Substances that Deplete the Ozone Layer of 1987 are strengthened and followed, there is a prospect that the Antarctic ozone hole will be repaired by 2100.
Ozone is destroyed in the Antarctic spring by chlorine formed during the sunless winter. T he chlorine is generated by an unusual reaction between stable molecules, on the surface of small stratospheric cloud particles which can only form in the intense cold of the polar winter. The stable molecules obtain their chlorine from CFCs which have previously been broken up in sunlit regions.

An important need is to determine the amount and the biological effects of the increased ultraviolet flux which is anticipated under a thinner ozone layer.