The phenomena we now popularly call the ozone hole( although it's not an actual hole – more like a depression ) was first observed by a research group from The British Antarctic Survey(BAS) in the 1970's. Joseph Farman, Brian Gardiner and Jonathan Shanklin, are the BAS scientists who discovered the Antarctic ozone hole by ground-based measurements from Halley Bay on the Antarctic coast, during the years 1980-84. At about the same time, an ozone decline was seen at the Japanese antarctic station of Syowa; this was less dramatic than those seen at Halley since Syowa is about 1000 km further north, and did not receive as much attention.



In 1984, when the British first reported their findings, October ozone levels were about 35 percent lower than the average for the 1960s. When the first measurements were taken, the drop in ozone levels in the stratosphere was so dramatic that, at first, the scientists thought their instruments were faulty. 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 and after that 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. Their discovery of the annual depletion of ozone above the Antarctic was first announced in a paper which appeared in Nature magazine in May 1985. Later, NASA scientists re-analyzed their satellite data and found that the whole of the Antarctic was affected.



The history of ozone measurements started in 1956, at Halley Bay. A few years later these were supplemented by measurements at the South Pole and elsewhere on the continent. They were originally intended for quite a different purpose, to study the structure and dynamics of the stratosphere, not its chemistry. Satellite measurements began in the early 70's, showing massive depletion of ozone around the south pole but the first really comprehensive satellite data came in 1978, with the TOMS (total ozone mapping spectrometer) and SBUV (solar backscatter UV) instruments on Nimbus-7( NASA ). However, these were initially rejected as unreasonable by data quality control algorithms (they were filtered out as errors since the values were unexpectedly low); the ozone hole was detected only in satellite data when the raw data was reprocessed following evidence of ozone depletion in in situ observations.

More recently an ozone hole has appeared over the North Pole. The ozone hole appeared first over the colder Antarctic because the ozone-destroying chemical process works best in cold conditions. The Antarctic continent has colder conditions than the Arctic, which has no land-mass. The ozone hole can be as big as 1.5 times larger than the United States.



The significance of this studies was in their eye-opening effect. It taught us that mankind can alter the environment on a planetary scale, possibly irrevocably...