Homage to Gaia

by James Lovelock

  We all were polarized and, like two opposing tribes at war, were prepared to think the worst of each other. This is no way to do science. The adversarial approach of the law court may have evolved to settle differences between people and between them and the law. It is wholly out of place as a way to advance scientific knowledge. During the early years, up until 1977, there was great ignorance, little solid evidence, and a flood of wild speculation about ozone depletion. The rocks on which this edifice was built were sound enough—the Molina–Rowland theory and my own measurements of the CFCs. The theory was universally respected; only its quantitative aspects were questioned. The CFC measurements were qualitatively approved; only their quantitative reliability was in doubt. The greatest exaggeration and the most nonsense was over the effects of ultraviolet radiation on living organisms. The stratospheric chemists were, frankly, ignorant about biology. They knew that the DNA of the cells absorbed ultraviolet radiation and that the DNA molecules were damaged. Some of them even knew that the damage occurred at the nucleoside base, thymine. This was enough knowledge for them. If ultraviolet damages DNA, the key molecule of life, then it is wholly bad and any depletion of the ozone layer, which increases ultraviolet exposure, must be equally bad. In the real world things are not so simple.

  A few biologists had experimented with the effects of UV on organisms in their natural state but their voice was not heard during the Ozone War. If it had been they would have warned that, apart from light-skinned humans, considerable increases in ultraviolet intensity seem to have little adverse effect on the biosphere at large. Going from northern Europe to the equatorial highlands of Kenya increases ultraviolet exposure eight times; this is forty times more than the modellers predicted the UV would increase through ozone depletion in the 1970s. Nowhere on Earth is there a UV desert, a place where life does not survive because the UV is too strong for it. There are hot deserts, cold deserts, and salt deserts, but nowhere is there a UV desert. Organisms, even tiny bacteria with the thinnest of membranes, find it easy to avoid damage from ultraviolet. They make pigments that absorb the UV harmlessly. They have evolved subtle repair systems for damaged DNA. Much of my own scepticism came because, in the Second World War, my colleagues at the Medical Research Council had tried to kill potentially harmful bacteria using ultraviolet radiation. What they found was that UV equivalent to sunlight unfiltered by ozone had little effect on many organisms in their natural state. It was easy to kill by UV the same organisms growing in transparent quartz vessels, but this is not evidence about the natural world. In their natural state organisms are protected by a thin film of secretion that absorbs the radiation. Lynn Margulis and M Rambler tried exposing algae to the ultraviolet intensity of unfiltered sunlight. The algae grew in spite of a daylong flux of this potentially lethal radiation. Even in Kenya, where the ultraviolet would burn light-skinned Europeans in minutes, there are no sunburned trees or grasses. In short, the widely held belief that life could never have existed on the land before ozone appeared in the atmosphere is a legend based on faith, not science.

  Life is tough and enterprising. The evolution of ultraviolet protection is easy; far less difficult than evolving ways to live in saturated salt or at temperatures near boiling. The main point of those concerned with ozone depletion was that sunlight harms people—especially light-skinned people. We suffer sunburn and skin cancers because of exposure to ultraviolet. They speculated about damage to the biota as if they were reporting facts of observation. I admit to being a finicky scientist, but I found offensive the claims that rabbits and sheep in the southern hemisphere were made blind by increased ultraviolet caused by the ozone hole. Equally, I scorned the stories of algal destruction by ultraviolet in the southern oceans. Many of these claims came from anecdotes, not from scientific observations. Like zealots of warring tribes, both sides used their speculations like atrocity fiction, not caring about the truth.

  The nadir of this affair for me was a meeting at Logan, Utah, in September 1976. Here were gathered the faithful among the stratospheric scientists, together with environmental lawyers, politicians, and a small defensive party from the chemical industry. When, during a session on UV-induced cancer, I showed a slide illustrating the physical and biological changes that vary with latitude on the Earth, the chairman, Dr Kauffman, interrupted. He glared at me and said, ‘You are not medically qualified; you cannot speak on these matters.’ In spite of my PhD in medicine, I sat down, realizing I might as well be trying to plead for contraception at the Vatican. All this followed an uncritical paper linking the incidence of melanoma, a fatal skin cancer, to latitude. The further south, the higher is the incidence of melanoma in the United States of America. My slide showed that not just UV intensity but skin temperature and the atmospheric abundance of free radicals also increased with movement south. No one wanted to know. This was not a scientific debate, it was not even a courtroom—it was a place where industry could be publicly judged guilty and not allowed a defence. All that was lacking was punishment.

  One person who understood my difficulties was the science writer, Lydia Dotto. Here is an account of her interview with me from her book, The Ozone War, published in 1978, and written jointly with the Canadian atmospheric scientist, Harold Schiff.

  In a way, Mrs Lovelock started it all. Back in 1970 when her husband, Jim, decided he wanted to measure fluorocarbons in the Earth’s Atmosphere, no one was much interested—certainly not the people who supplied funds for scientific research in his native England. So Mrs Lovelock, the family business manager, broke out the grocery money, and with it her husband built a sensitive instrument that soon detected minute amounts of fluorocarbons in the atmosphere. These chemicals did not come from nature; they were man-made, and it was not hard to figure out where they did come from. What Jim Lovelock was measuring was largely the accumulation of several decade’s worth of hair spray and deodorant propellants, with perhaps a small amount of refrigerant and air-conditioning coolants thrown in. Though neither he nor his wife could know it at the time, their modest investment in pure scientific research would threaten the billion dollar refrigerant and spray can industry and touch off one of the major environmental rows of the decade.

  But Lovelock was no environmental crusader. He is an unassuming Englishman with modishly long greying hair and a soft almost hushed voice. There is a gentleness about him that provides a striking contrast to the rather high-powered American scientists who dominate the ozone controversy.

  When I returned home from Logan, I was surprised to find a letter waiting for me from Dr Kauffman. It was a friendly letter and mainly to ask for help with a problem involving the electron capture detector. It was not an apology for having denied me my chance to speak, but reading between the lines, I sensed his need to make amends.

  It was not long afterwards that Frank Bower and Ray McCarthy asked me whether I thought it feasible to set up a global monitoring network to measure CFCs in the atmosphere. Their reason for asking was that they had seen a proposal to the Chemical Manufacturers Association, the academic grant-funding agency of the industry, from Professor Ronald Prinn of the MIT. He proposed calculating the atmospheric residence times of the chlorofluorocarbons from accurate measurements of their atmospheric abundances in both hemispheres. Knowledge of the residence times was important for calculating whether CFCs were as dangerous as the stratospheric chemists feared. My reply was, yes, that four stations, two in the northern hemisphere and two in the southern hemisphere, should be sufficient to monitor long-lived gases like CFCs. I was less certain, however, that the required accuracy, better than five per cent, could easily be achieved. I offered to install immediately a new gas chromatograph at my monitoring station in Adrigole in Ireland. I would run it continuously for a year to check its reliability and accuracy. Here was an example of the value of independent science. If I had asked the CMA for money to buy the GC and funds to test it for a year they would have provided it, but I would have had to wait a year for their decision, and lon
ger for the money. As it was, I purchased immediately from my own pocket a new gas Chromatograph from Hewlett Packard and expected that the CMA would reimburse me sometime later. In fact, they never did. The year’s trial at Adrigole showed that an unattended gas Chromatograph could make as many as six automatic measurements a day. Moreover, the accuracy of the measurements appeared to be sufficient. Prinn’s proposals were then accepted and funded. The Adrigole station was included within the atmospheric long-range experiment (ALE). The other stations were in Barbados, Samoa in the Pacific, Cape Grim in Tasmania, and Cape Mears in Oregon, USA. They were all set up exactly according to my instructions, using the same equipment that I had tested in Adrigole. Prinn’s proposal was justified and we now know the residence times of CFC gases. These stations, except Adrigole, still operate and provide valuable information on the abundance of CFCs and other halocarbons.

  By 1978 I could no longer run the Adrigole station, and I passed the management of it to Peter Simmonds of the ALE experimental team. Helen’s increasing disability from multiple sclerosis made this decision unavoidable, since she was no longer able to travel with me to Ireland. Sadly, my departure from Adrigole led to the closure of the station. Within a few years, the politics of big science was used to justify moving the measurements to another Irish station, Mace Head, in Galway. This was a bad move scientifically: it lost two years’ observations. At least ten atmospheric scientists—including Michael Prather, Michael McElroy, Steven Wofsy, Gary Russell, and David Rind—opposed in public the closing of the Adrigole station. It was not just bad science, it also deprived my friend and neighbour, Michael O’Sullivan, of the chance to participate in, what was for him, fulfilling work. When we moved to Adrigole in 1965, Michael O’Sullivan was working as a small farmer scraping a bare living from the well-named Hungry Hill. Our presence opened a new world for him and his family and, although he had no scientific training whatever, he became, working with me, a skilled and diligent technician. He kept the apparatus running throughout the years of its use at Adrigole and he kept a record, using a sun photometer, of atmospheric turbidity. Michael and Teresa O’Sullivan’s unstinted help and friendship made possible the Adrigole station. Without it, we might not have discovered the accumulation of CFCs for as much as another decade. The closure of the station was untimely, unnecessary, and brutally done. At the time, I was fighting my own battles with illness and could not help. It was a shameful affair, for in the late 1980s I discovered that UK grant-funding agencies were generously funding the monitoring of CFCs at Mace Head. I had assumed that their earlier disdain for my own efforts was a price I had to pay for pioneering and for independence. Now I felt chagrin because, among those who now received grants, were members of the grant committees. I was a fool to feel this way: cronyism is everywhere, why should I think science was different? I do not regret following Rothschild’s advice to keep away from committees. Grants are a form of welfare and I did not need it. Even so, I feel incensed that I had no say in the closing of the Adrigole site. I would have been glad to recommend compensation to Michael O’Sullivan for his long service keeping the Adrigole station running.

  My last work for the Ozone War was to develop a method of calibrating the monitoring instruments. It all began when I was preparing for the Shackleton voyage in 1971. It was easy enough to detect CFCs in the air using a gas Chromatograph equipped with an electron capture detector, but I did not know how accurate my measurements would be. There were two ways to calibrate the instrument. First, I could take a minute but accurately known amount of pure CFC, dilute it in a large volume of air, and then use a sample of the dilute CFC to calibrate my gas Chromatograph. This was not a good method for CFCs: they were everywhere, so where could I find fifty cubic metres of air uncontaminated by CFCs? Some chemists tried diluting CFCs in pure gases such as nitrogen to a few parts per million. Then they further diluted the few parts per million to a few parts per billion, and finally to a few parts per trillion. I was too much of a hands-on chemist to have any trust in such a serial dilution procedure. I happily acknowledge the skill of Ray Weiss, who pioneered the direct dilution technique to make calibration at the parts-per-trillion level possible, but this was not available until the mid-1980s.

  My Green friends, many of whom believe in homeopathy and other kinds of alternative medicine, may be interested in my views on this kind of dilution. Homeopathic practitioners regularly serially dilute their drugs to levels trillions of times lower than parts per trillion. My experiences showed how difficult it is to dilute simple inert chemicals like CFCs. They made me deeply sceptical about the extreme dilutions of homeopathy. On the other hand, there can be few things as harmless as a drug applied homoeopathically, and there would be no side effects.

  The other way to calibrate the Shackleton chromatograph was to make an absolute detector. This is an old trick of instrument scientists. It is simple to do, but it requires a theory of how the detector works. I assumed that the reaction between free electrons that were floating inside the detector and chlorofluorocarbon molecules led to their mutual removal from the detector. Each electron lost this way was then equivalent to one CFC molecule. I knew the average numbers of electrons in the detector quite accurately from the current flowing in it. A typical detector current of a hundredth of a microampere is exactly equivalent to 62.415 billion electrons per second. So if CFCs at a flow of ten billion molecules per second were passed into the detector, ideally they should remove ten billion electrons per second and hence decrease the current flow by 1.602 nanoamperes. From the simple arithmetic it was not difficult to calculate, from the area of a chromatograph peak, how many electrons were removed and hence how many CFC molecules had reacted. Reality is more complicated. Some of the CFC molecules could escape reaction and fail to be counted. To answer this, I joined two detectors in series and detected the amount of CFC that escaped through the first detector. It turned out that forty per cent of the CFC escaped the detector I was using. Therefore, I had to correct my first estimate by this amount. There were other more recondite doubts, mainly about other reactions of the CFC molecules in the detector. Nevertheless, I chose to use this absolute procedure to quantify my measurements made on the Shackleton expedition. This was both foolhardy and brave. First measurements have no predecessors to compare with. If I were badly wrong about absolute detection, I could not have chosen a better way to advertise my error than the first paper on the global distribution of chlorofluorocarbons that was published in Nature in 1973.

  The first time that this procedure was called to account was at a meeting of the United States National Academy of Sciences’ panel on ozone depletion. It was at the ski resort of Snowmass in Colorado, which is a beautiful place, at about 8000 feet up in the Rocky Mountains. One of the panel scientists asked, ‘How accurate are your chlorofluorocarbon measurements?’ ‘About twenty per cent,’ I replied. Twenty per cent accuracy implies that a quoted value of 100 parts per trillion represents a true value in the range 80–120. The errors start when the air sample is taken. How close in volume is the air sample to the 5 cc marked on the syringe used to collect it? They end with the estimate of the peak area of the chromatogram. On the Shackleton, I did it using a pencil and ruler. These errors added up, I calculated, to make an uncertainty of about twenty per cent. The true error may have been less but I had learnt in a lifetime of measurements that it is best use the worst estimate when trying to guess errors. Almost immediately, an American analyst present at the meeting jumped up and said, ‘Oh, I can measure the CFCs to a one per cent accuracy.’ I was impressed; I knew that my home-made apparatus and dubious syringe method of sampling were less professional than I would have wished. I had not realized how far ahead the high technology of the United States had gone. The panel was equally impressed and in its published report categorized my measurements on the Shackleton as inaccurate. It took me five years to discover that the claim of one-per cent accuracy from the young man who jumped up at Snowmass was false. The claimant, I discover
ed, was hazy in his mind over the difference between accuracy and precision. He meant one-per cent precision, not one-per cent accuracy. The difference is this: a badly inaccurate but precise weighing machine will record your weight as 90 lbs, never varying from 89 to 91, when in fact your weight is 150 lbs. An accurate but imprecise weighing machine will give weights between 130 and 170 lbs, and if you weigh yourself often enough will provide an average close to your true weight.

  A professional body, the US Bureau of Standards, also grew suspicious of the analyst’s ability to measure CFCs with such astonishing accuracy. Ernest Hughes, William Dorko, and John Taylor of the Bureau designed an experiment to find out the truth about these claims. They filled one set of small gas cylinders with clean air and another set of cylinders from a batch of the same clean air with some pure nitrogen added to it. They sent one each of these cylinders to the principal analysts measuring CFCs in the atmosphere, and asked them to report their findings. When they returned their measurements, the National Bureau of Standards plotted the two measurements from each analyst on what statisticians call a Youdon plot. This is a graph where the value of one measurement is marked by its position on the horizontal axis and the other measurement by its position on the vertical axis. If all the measurements were accurate to one per cent then all the reported values would have centred within a small circle—like the throws of a champion darts player, all in the bull’s eye. In fact, the FC11 results were scattered over a range going from less than half to more than twice the true value and the FC12 results were worse even than this. My twenty per cent did not look so bad compared with this. Their report, which revealed inaccuracy throughout the community, brought me sharply back to my student encounter with Professor Todd, and the time when he could not believe the accuracy of my student exercise, not knowing about my professional training. Scientists working at universities, and using unfamiliar techniques, often make inaccurate measurements because they rarely have the time to become proficient.