Homage to Gaia

by James Lovelock

  Daisyworld is the first mathematical model of a world that evolves by Darwinian natural selection, and on which the evolution of the environment, represented by temperature and the evolution of the organisms, is a single coupled process. The self-regulation of global climate emerges as the model evolves. It is both a simple climate model and a population biology model. Peter Saunders, Professor of Mathematics at King’s College London, wrote a fine paper for the Journal of Theoretical Biology in 1994 analysing the mathematics of Daisyworld and confirmed it as a valid evolutionary model. Few biologists seem to agree and some even refer to it as a mere computer game. There are fouls in science, just as in sport, and this foul criticism of Daisyworld is an own goal. No competent computer modeller would make the mistake of denigrating a computer game. However trivial the play, it can take the imagination of an artist and the skill of a wrangler to write the program for a game. A high moment in my quest for Gaia was a visit to Coombe Mill of a talented game programmer, Will Wright, who was at that time with the firm Maxis, and who had developed the popular game SimCity. He asked me if I would collaborate with them to produce a game about the Earth called SimEarth, which would include versions of Daisyworld. It was a thrill and enlightenment for me to work for a while with so competent a computer programmer. Maxis, without my asking, paid royalties from the sales of SimEarth to our charity, Gaia, that sustained our research during a difficult time.

  The years between 1979 and 1984 were difficult. No matter how I tried to persuade scientists that they should take Gaia seriously, I rarely succeeded. Through the 1980s, Gaia was treated more as science fiction than science, and it became almost impossible to publish a paper with Gaia in the title or even in the text, unless it was to denounce it. The New Age movement took Gaia to their bosom but, sadly, too many of their good intentions were neutralized by a lack of rigour. The rejection by some New Agers of science itself made my task even harder. It confirmed for many senior scientists that Gaia was not only wrong; it was dangerous. They saw it as a topic like astrology that masqueraded as a science but was nonsense. An outstanding exception to the loose thinking of the New Age was the journal Co-Evolution Quarterly, under the editorship of Stewart Brand. The journal published several articles from Lynn and from me and from scientists who criticized Gaia. Stewart and Patti, his wife, became good friends, and we have visited and corresponded over the years.

  A great comfort during these bad times was the presence of Teddy Goldsmith at Withiel, not far from Coombe Mill. Teddy was much like my Uncle Hugo Leakey—wonderfully erudite, fast on his feet in argument and, like his famous brother Sir James Goldsmith, effective. He was a fine critic and needed to be, because there were many issues of Green politics on which we disagreed, notably my liking for nuclear power. Teddy had more influence on my thinking than I think he knew. His strength and consistency made him for me a touchstone on Green affairs and his book on Green philosophy, The Way, is a powerful statement of the philosophy behind Green thinking. Teddy and his wife Kathy lived in a manor house where they lived a life consistent with their principles, even to the extent of using earth closets inside the manor house. Few things vex me more than Green hypocrisy, such as the sight of a monstrous four-wheel-drive gas-guzzler with a sticker on the back bearing some trendy Green message.

  The disappointment I felt over Gaia’s rejection was intensified by my problems at home; Helen was slowly losing her battle with multiple sclerosis, and I seemed to spend too much of my time in hospital for surgery. The 1980s were a decade of pain and long discomfort. Of course, there were good moments: visits to and from Bob and Cynthia Garrels were joyful events. And looking back, I think I was too depressed by my personal problems to notice that the work I did with Andrew Watson and Michael Whitfield at the Marine Biology Laboratory in Plymouth, was key to the establishment of Gaia theory in science. I had long thought that the observation that CO2 in the soil throughout the world was concentrated between ten and thirty times more than in the atmosphere was important evidence for Gaia. Biogeochemists accepted the evidence and agreed that it was due to the metabolism of soil micro-organisms, but they failed to see its significance globally. I saw the high concentration of soil CO2 linked with faster rock weathering and a greater rate of removal of CO2 from the air, which in turn leads to a cooler global climate. We proposed that the weathering of the rocks by carbon dioxide and rainwater was part of a self-regulating process, which involved the living organisms in the soil. When it was warm, growth was faster, more carbon dioxide was pumped from the air, and any tendency to excessive heat or carbon dioxide was resisted. By this and other means the Earth was kept always at a comfortable level for life. We argued that rock weathering was more than just a geochemical activity, because the rocks were always in contact with organisms ranging from bacteria, through lichens, to plants, and we suggested that weathering took place at least ten times faster as a result. Not only this, but because plant growth is temperature-sensitive, the presence of organisms coupled climate to weathering, and to the rate of removal of carbon dioxide from the air. This long-term geological process has kept the Earth at a favourable temperature as the Sun has warmed up. We published these ideas in two papers in the early 1980s and the American scientists, David Schwartzman and Tyler Volk confirmed them by experiment in 1989. They are now part of the wisdom of Earth System Science.

  I was always seeking possible mechanisms for the self-regulation of climate, and the work of Glenn Shaw, an aeronomist working at the University of Alaska, intrigued me. He proposed that the biological emission of sulphur compounds from ocean sources was the source of the sulphate aerosol in the stratosphere. This aerosol reflects sunlight back to space and makes the earth cooler. It occasionally increases in density when volcanoes inject sulphur dioxide into the stratosphere, and consequently several years of cold weather follow the eruption. Glenn Shaw suggested that the biological emission of sulphur gases from the ocean might be part of a climate-regulating mechanism. It might have been in the Earth’s past, but it seemed that at present the climatic effect of the background stratospheric aerosol was small.

  The event that was to lift Gaia theory from its mid-life doldrums came unexpectedly. In 1986 the ocean scientist, Dr Murray, of the University of Washington in Seattle, invited me to be a Walker Ames Visiting Professor. This involved a month’s visit to lecture and to interact with students and scientists of the university. Following a lecture in the Chemistry department, I had a fruitful discussion with Robert Charlson, a distinguished atmospheric scientist interested in clouds. Bob Charlson belied the name of his calling, he was no light ethereal being, but one with feet firmly anchored to the ground. He is a dark-haired sturdy man with the look of a sailor, and he would have fitted naturally on the quayside of my nearest fishing village, Port Isaac. I am proud to have him as a friend.

  Bob told me that there was an unanswered question about clouds over the ocean. What is the source of the tiny particles, the nuclei of water-soluble substances, from which clouds form? Without these nuclei, there can be no clouds. When Bob said this, I was surprised. Surely, the water that evaporates from the warm sea will condense into droplets as it rises into the cold air. ‘Yes,’ he said, ‘it will. But the droplets will be large because there are few nuclei for them to condense on. They will not be cloud droplets, which are so small that they almost float in the air. They will be large drops that fall from a clear blue sky.’ He went on to say that over the land there are always particles for clouds to form on, such as the sulphuric droplets of air pollution; over the oceans, apart from a few volcanoes on islands, there are no sources of these nuclei. We used to think that sea-salt crystals blown and dried by the winds from the sea were the condensation nuclei. We have sampled the air over the Pacific Ocean far from land and we find a few sea salt crystals, but we always find abundant nuclei in the form of droplets of sulphuric acid and ammonium sulphate. Bob finished with the question ‘Where does this sulphuric acid and ammonium sulphate come from?’ It was one o
f those important moments in science. I had lectured the previous day on the regulation of the sulphur and other chemical cycles through the emission of dimethyl sulphide from ocean algae, and suddenly it occurred to us both that the oxidation of dimethyl sulphide could make the cloud-nucleating sulphuric acid droplets. We went on to wonder if this was part of some large-scale climate self-regulation. By coming to Seattle and talking about Gaia, Bob and I had been able to share two essential pieces of information that solved the puzzle: where do the clouds over the ocean come from? Here perhaps was the most important scientific discovery that either of us had made. Without the clouds over the ocean, life as we know it would not exist. This is because oceans cover seventy per cent of the surface of the Earth, and they are dark, and absorb sunlight strongly, whereas clouds are white and reflect sunlight. Bob told me that without clouds the Earth would be about twenty degrees Celsius hotter and that a cloudless Earth would have a surface temperature near 35° C, which would make the world inhospitable for our kind of life. There are other sources of nuclei for cloud formation, but we did think it reasonable to speculate about the link between climate, clouds, DMS, and algae as part of Gaia’s self-regulation. There was little doubt that the microscopic algae of the oceans were the principal source of DMS.

  We decided to put our ideas in print as an article in Nature. We sought the help of Bob’s graduate student, Steven Warren, and the eminent geochemist, Andi Andreae, who knew more than anyone else about the DMS emissions from the oceans. Moreover, the editor of Nature at that time, John Maddox, had written to me to express his regret that Nature had turned down the Daisyworld paper. He invited me to send the next Gaia paper to him personally. I sent our paper to Nature with a covering letter to the editor marked ‘Personal’. True to his word, after a proper round of peer review, the journal published our paper as a lead article. I consider it one of the most important scientific papers I have participated in. So did the scientific community, for two years later, they awarded the four of us the Norbert Gerbier Prize of the World Meteorological Organization (WMO). This paper was the turning point for Gaian fortunes, and has started a scientific enterprise linking algae to the climate and chemistry of the atmosphere that must now employ hundreds, if not thousands, of scientists worldwide.

  It was natural for me to think that the success of the cloud algae research would make Gaia a respectable name in science, but the conference held in San Diego in March 1988 by the American Geophysical Union soon dispelled this illusion. The distinguished climatologist, Stephen Schneider, and the MIT professor, Penelope Boston organized this meeting on Gaia against considerable opposition from conventionally minded geophysicists who thought that to hold such a meeting would bring disrepute to the society. Naïvely, I saw their conference as a wonderful opportunity to establish the scientific respectability of Gaia. I spent many weeks putting all I knew, as succinctly as possible, into my paper ‘Geophysiology—the Science of Gaia’ and was given the opportunity to open the meeting. They heard my paper almost without comment. Lynn and Greg Hinkel followed it with a paper entitled ‘The biota and Gaia: 150 years of support for environmental science’. Lynn and I had by now established a double act in which she argued from biology and I argued from physical chemistry. The audience listened politely but said little. Then came David Abraham’s moving philosophical paper, and a long run of papers which had little to do with Gaia directly. There were some good sound criticisms by Ken Caldiera and Dick Holland, but most speakers chose a topic connected with their own work.

  One delegate, my friend Ann Henderson-Sellers commented: ‘This meeting is like the parable of the three monkeys. One sees no Gaia, one hears no Gaia, and one says no Gaia.’ This went on until the session on Wednesday evening when a young physicist, James Kirchner, gave his talk ‘The Gaia Hypotheses: are they testable? Are they useful?’ In the manner of a skilled barrister he took selected quotes from my early papers and from my first book. He ignored their context and used the quotes to ridicule and diminish Gaia theory. He ignored entirely the paper I had just given at the meeting. I listened with growing chagrin as he proceeded with forensic skill to dissect, sterilize and destroy the separated parts of Gaia. I should have risen and replied vigorously, by arguing that Kirchner’s arguments were sophistry, not science, and that Gaia can only be considered as a whole system, but I am not a natural debater. All I could do when I went to the lectern to reply was to congratulate him on his skill and ask for time to think before I replied. James Kirchner’s was by far the best presented speech, and so strongly influenced the meeting that, from then on, few took Gaia seriously. Richard Kerr, writing in Science, shared Penelope Boston’s view that the jury was still out, but D Lindley, a staff writer for Nature, confirmed my own opinion that Kirchner’s speech carried the meeting. The organizers invited me to speak after the conference dinner and, sensing the mood, I asked, ‘Is Gaia just a spoof?’, and received a burst of laughter. I went on to say that I would be proud if one day Gaia was described as Popper had described the Theory of Evolution: merely a research programme in metaphysics. My after-dinner speech won a standing ovation, but it was for me as a good loser, sadly not for Gaia who I thought I had betrayed. You will find our speeches in the book of the meeting edited by Stephen Schneider and Penelope Boston: Scientists on Gaia. From then on scientists rarely ever spoke of Gaia, but the science of Gaia—the understanding of the Earth through geophysiology, flourished. It was the Gaia legend that languished. My memories of the San Diego meeting are sad and were made more so by a telephone call from Cynthia Garrels to tell me that her husband and my friend and supporter Bob Garrels had died.

  One reason why Gaia has had a hard time is that few scientists have a proper grasp of self-regulating systems; these are often transdisciplinary and modern scientists are most often specialists. There are notable exceptions, and the first to come to mind is Christian de Duve, the Belgian biologist whose enthralling book Vital Dust presents the most convincing account I have read of the events in the evolution of life starting from Earth’s primeval surface chemistry. Inventors intuitively understand self-regulation but such understanding is denied to some of our most competent analytical mathematicians. One of the first successful self-regulating devices was James Watt’s steam-engine governor. This simple device regulates the speed of an engine by means of a pair of spinning balls mounted on a vertical shaft. The rotation of the shaft causes the balls to spin out and move a lever that partially closed the valve supplying steam to the engine. If the engine went too fast, the balls swung further out and shut off the steam, if too slow they fell inwards and increased the supply of steam. It worked wonderfully well and was demonstrated at a Royal Society Conversazione in London during the 19th century. Among the audience was James Clerk Maxwell, perhaps the greatest physicist of his time. He is reported to have said three days later that he was kept awake trying to analyse mathematically Watt’s invention; he had no doubt that it worked but analysis eluded him. If it was too difficult for Maxwell to analyse then it is hardly surprising that the more complex system Gaia is not immediately obvious to most scientists.

  In October 1988 Sandy and I were in New York for the launch of my second book, The Ages of Gaia. Ed Barber of the distinguished American publishers, WW Norton, was our host, and the Commonwealth Fund, who supported me while I wrote the book, had arranged a party to celebrate its publication. Among the guests was the United Kingdom’s permanent representative on the UN Security Council, Sir Crispin Tickell. I was delighted to meet him, for I recalled with pleasure the kind letter he had written after the publication of my first book. We tried to talk, but were frustrated by the noise of the reception and the effort of eating while trying to hold in one hand canapés and a glass of wine. We arranged to talk under quieter conditions over breakfast. Sandy and I were staying at the Algonquin, and next morning, in a quiet alcove chosen by the head waiter, we enthusiastically exchanged our ideas on climate change and Gaia. From our meeting came a lasting friendship. Sir Cr
ispin has done more than anyone to make the idea of Gaia acceptable, especially among the powerful and influential circles in which he moves. As I mentioned earlier, TH Huxley, who did so much to establish Darwin’s science, was his great-great-grandfather. I am deeply grateful to have so staunch a friend. He told us that he would be retiring from his Ambassadorial post in the autumn and would be returning to England to become the Warden of Green College, Oxford. As Warden, he founded the Green College Centre, and so gave Oxford a global presence in environmental affairs. He also endorsed the College’s invitation to me to become an Honorary Visiting Fellow. My battles for Gaia have taught me the value of an elevated position in the very human affair of science. For this I shall always be grateful to him and to Sir John Hanson, his successor as Warden, for sustaining my Fellowship.

  In the summer of 1988, the publishers Jos and David Pearson of Gaia Books asked me if I would write a book on Gaia for them. I gladly accepted their offer as the chance to put on paper my ideas about planetary medicine. It would be a book about the Earth that saw it as sufficiently alive to suffer disease and then try to understand the Earth system through the perturbations of its maladies. I gave the book the title The Practical Science of Planetary Medicine. Not an exciting title but alternatives such as ‘Earth Medicine’ all seemed even more misleading. Gaia Books published it in the United Kingdom in 1991 and it is the book that I think best expresses the practical science of Gaia. The American publishers Harmony Books issued it in the United States under the title Healing Gaia because they were sure that my choice of name was wrong. It turned out that they were even more wrong and booksellers put the book on their New Age shelves along with books on astrology, aromatherapy, and the usual range of New Age topics, where it languished.