The next major development in the story took place in 1985, when the discovery of the Antarctic ozone hole was announced. This did not happen until about eight years after the effect first appeared. It was a surprise announcement from a group that had been involved in the routine collection of data from a British Antarctic station for many years. Those involved with more sophisticated satellite-based ozone monitoring experiments had missed the effect completely, though they were able to find it in their data once the British announcement had been made. We will examine the rather surprising delay in discovery by the British team, and failure to discover by the NASA team.

In 1985, a letter was published in Nature, which dramatically changed the course of scientific investigations of stratospheric ozone (Farman et al., 1985). A team of scientists from the British Antarctic Survey reported a very large seasonal fall in column ozone values measured over their station at Halley Bay in Antarctica. Every year in September and October, ozone levels were falling significantly – typically by about 25 per cent, but sometimes by as much as 60 per cent.

The decline had started around 1976. Nineteen years of carefully collected data between 1957 and 1975 showed no such effect. But in the eight years from 1977 to 1984 the effect was clearly apparent, and seemed to be increasing. By about mid-November each year, the levels were returning to normal.