Free Radicals - Michael Brooks [103]
The spectrophotometer at Halley Bay measured the ozone concentration in the sky above by checking which frequencies of light made it through the atmosphere and which didn’t. The more UV that made it through, the less ozone there must be in the stratosphere. But Farman’s instrument was nearing the end of its life; a replacement was waiting in Cambridge. When that replacement was finally installed and began taking measurements, it found the same seasonal dip in ozone. The 1984 readings showed a 40 per cent dip over a period of around 30 days between September and October. The hole stretched from Halley Bay to a second measuring station a thousand miles to the north-west. It was a big hole, in every sense.
So why hadn’t the NASA satellite seen it? A pervasive rumour quickly circulated among the ozone-hunting community: the program NASA was using to analyse the satellite data had thrown out the anomalously low values. Though an appealing idea – schadenfreude is alive and well in science, especially when researchers are looking across national and cultural borders – it is not quite true. The NASA satellite receiver marked the data as anomalous: very different from what was expected, and probably the result of error. The anomalies were ‘flagged’ for checking later. Unfortunately for the NASA researchers, when they got round to it, they checked the anomalies against the readings of the Amundsen-Scott ground station, and its instruments, unlike Farman’s, were awry. Amundsen-Scott was recording ozone levels nearly twice as large as those the satellite recorded. And since that was more in line with expectation, the NASA researchers relaxed.
This is not to say that they threw the anomalous data out – they just took their time. It was a delay that the team leader, Richard McPeters, is probably still cursing to this day. We saw in Chapter 2 that data can be slippery. We saw in Chapter 6 that being first to a solid result is everything to the scientist. Perhaps that’s why McPeters has since claimed to be the first to report the ozone hole, in an abstract submitted in ‘late 1984’ to the organisers of a Prague conference. But Farman remains the man officially recognised as finding the Antarctic ozone hole. His team sent their findings to Nature in December – they arrived in Nature’s offices on Christmas Eve – and they were published, to universal astonishment, on 16 May 1985.
According to the historian of science Maureen Christie, the hole could conceivably have been found as early as 1981; the British team ‘could have saved two years if the data backlog had not developed, and up to another two if the team leader had been a bit less cautious’. NASA, meanwhile, had set up their system on the assumption that data on Antarctic ozone would be mundane rather than interesting, with no allowance ‘for the possibility of surprises’. So it was that, eight years after the hole appeared, the scientists finally had something with which to shock the politicians into action.
Experts at the United Nations Environment Programme now estimate that the 1987 Montreal Protocol, the international treaty that limited emissions of ozone-depleting chemicals, prevented up to 20 million cases of skin cancer and 130 million cases of eye cataracts. In 2010 they reported that ozone concentrations are no longer decreasing. Though they are not yet increasing, pre-1980 ozone levels are expected to be regained before 2050 over most areas of the Earth. Over the poles, where the most severe depletion occurred, full recovery may take an additional fifty years. In the face of the CFC crisis, no one can pretend that all the inventions of science are an unqualified boon. But at least free, radical scientists can help to solve the problems that progress creates.
In 1963, Dennis Gabor published a book called Inventing the Future. It makes fascinating reading now, because Gabor, a Hungarian-born scientist and inventor (of the hologram, as it happens, for which he won