Few of us, I suppose, react as emotionally as did Julian Lennon:
We are a rock revolving
Around a golden sun;
We are a billion children
Rolled into one;
So when I hear about
The hole in the sky,
Saltwater wells in my eyes.
But perhaps we should.
It was early in 1985, in the science journal Nature, when Joe Farman and two colleagues announced the presence of an "ozone hole". The evocative name is applied to a dramatic decrease in ozone concentrations which has been found to occur every southern spring high over the South Pole.
Each year the decrease becomes obvious in September, just as the sun begins to peep over the horizon after the long polar night. It intensifies during the following weeks and then, in late October or November, the "hole" fills up again, and ozone concentrations return to near their normal values.
And so this time every year many meteorologists fix their gaze on the antipodes. Data on these matters are collected by many agencies around the world and collated by the World Meteorological Organisation (WMO) in Geneva.
WMO publishes regular bulletins on the ozone hole during the critical months, and its latest missive on the subject was released last week.
It seems that by the end of September this year the Antarctic ozone hole had become the "deepest" on record: there was less ozone in the upper atmosphere over the South Pole than has been the case in any previous year since observations of the phenomenon began.
Over some 20 million square kilometres, an area 2 1/2 times the size of Europe from the Atlantic to the Ural Mountains, stratospheric ozone amounts were below 50 per cent of normal values.
Since the lowest values of the season consistently occur in early October, we can expect the hole to have become deeper and larger still before the usual recovery begins.
The high rate of ozone depletion this year was largely expected. Very low temperatures are required for man-made catalysts which have drifted into the stratosphere to initiate the destruction of the ozone, and this year temperatures high in the atmosphere over Antarctica were significantly lower than usual in July and August.
Indeed, these abnormally low temperatures are probably themselves a consequence of the periodic lack of ozone. Solar radiation, which would otherwise be absorbed by ozone in the stratosphere, thus raising the temperature in those regions, now often passes more readily downwards towards the surface of the Earth to contribute to the other great meteorological problem of our age, global warming.