James Lovelock shares at least two things with Charles Darwin. One is that as a child he roved in the same Kent countryside near Orpington. The other is that popular conceptions of his scientific ideas often bear only a sketchy correspondence to his actual words. Although Lovelock's idea that the Earth is a super-organism, which he calls Gaia, has become a keystone of the environmental movement, his relationship with environmentalism is ambivalent and many greens would be shocked by his views. He is unrepentant about naming his hypothesis, at William Golding's suggestion, after a goddess. But he now encourages the term "geophysiology" in an attempt to shed the theory's mystical baggage. His talk of the "need to regain our ancient feeling for the Earth as an organism and to revere it again" resonates with grassroots environmentalism, yet Lovelock pulls no punches about "idiot greens, who are mostly innumerate and would freak out if you showed them an atom of chlorine." His private laboratory in Cornwall displays this dichotomy: outside, the white plaster figure of Gaia; inside, radioactive warning signs.
Both science and its sceptics need men like Lovelock. He does not fit into any camp, provoking scientists to think "outside the box" while imploring greens to learn some facts and figures. Moreover, Lovelock has won scientific respect by being patient, dignified and non-dogmatic in arguing his case, and by being explicit about its provisional nature. If you sense that nevertheless Lovelock suffers little fear that he is wrong, this is scarcely surprising, given his record of overturning entrenched wisdom. His early victories turned on robustly practical science-and it is the rewards from such work which make possible Lovelock's unusual status as a self-funded scientist.
Like many scientists of his generation, Lovelock regards the creativity of his formative years as fostered by an environment free of both the competitiveness and high financial stakes which characterise much research today. Raised in Brixton, the son of a gas board employee, he completed a chemistry degree in Manchester and then took a job in the 1940s with the Medical Research Council in London, which then boasted figures of world renown, such as Peter Medawar, John Cornforth and Archer Martin.
Lovelock was set to work on cryopreservation: freezing and reviving organisms. To warm up frozen mice and hamsters quickly, yet with minimal trauma, he hit on the idea of using microwaves. He used his device to heat his lunch too, but never dreamed of patenting the idea. Who, after all, would want to cook a meal with microwaves? Besides, the device cost about ?10,000 and "looked like a huge bomb."
It was his subsequent innovation that proved pivotal to his career. Lovelock found that much of the damage a frozen animal sustains is caused by the changes in their membranes. To understand these processes, Lovelock needed to analyse the molecular composition of membranes. He hoped that Archer Martin's technique of chemical analysis would do the trick, but Martin baulked at the tiny size of the specimens Lovelock produced-far too small for reliable measurements. "You could go and invent a more sensitive detector," Archer quipped. Lovelock did.
The result was the electron capture detector (ECD), an offspring of necessity wedded to serendipity. The device was peculiarly sensitive to certain human-made organic particles or vapours, such as the fumes of chlorinated organic solvents like chloroform. And Lovelock reasoned that the processes involved in triggering the detector would be similar to those which take place during oxygen-driven metabolism in our cells-in which case these organic compounds might interfere with cell function in harmful, perhaps carcinogenic, ways. It was hardly a thorough hypothesis, and it was roundly ridiculed at the time-the solvents were widely used. But industrial chlorinated organic compounds such as PCBs and dioxins are now recognised as some of the most dangerous contaminants in the environment.
Lovelock devised the ECD in 1957 and developed it into a reliable, cheap and portable instrument in 1959, while on sabbatical at Yale University. His US hosts were cannier about patent rights, and encouraged Lovelock to apply for them. Yet once the patent was granted in 1963, the US government decided that as the work was done at Yale, all patent rights devolved to the US state. Lovelock had to accede, and thereby lost about $20m in royalties.
Lovelock's philosophical attitude to the affair seems genuine, coming as he does from a tradition in which money and creative thinking are regarded as having an inverse relation. "I'd probably have been corrupted and wouldn't have had any urge to work." Besides, the invention of the ECD established Lovelock's reputation sufficiently for Hewlett-Packard to put him on a retainer for rights to subsequent innovations, helping to fund his later private research.
In any event, the real significance of the ECD was not financial, but where it led Lovelock's thinking-away from biology, and into the air. The detector's ability to sense tiny amounts of synthetic organic contaminants recommended it to companies such as Shell, for environmental monitoring, and to the US Food and Drugs Administration, for detecting pesticides in food. But in 1966, while on holiday on Ireland's Atlantic coast, Lovelock smelt something else: smog.
The nose is often a wonderful detector, but it doesn't generate scientific data. So Lovelock made some measurements with his ECD, tuned to sense the synthetic chemicals called chlorofluorocarbons (CFCs). Widely used in refrigerators, aerosol sprays and as industrial foaming agents in the 1960s, CFCs were a convenient fingerprint of urban air pollution. Although meteorologists denied that such contamination could travel so far from an urban centre, Lovelock's detector was capable of sensing the previously undetectable. He found CFCs at the level of around 150 parts per trillion-a few drops in a swimming pool-in the air from Europe. Lovelock also found CFCs at lower concentrations in air coming off the Atlantic. Could they have travelled from America? To test the idea that air pollution could reach this far, Lovelock travelled to Antarctica in 1971, and found CFCs in the polar wastes at 40 parts per trillion.
Still conventional wisdom resisted, and for several years his measurements were denounced as bogus. Among those who believed them were US atmospheric scientists Sherwood Rowland and Mario Molina. In 1974 they proposed that if CFCs stay in the atmosphere long enough to spread globally, they could partake in chemical reactions in the stratosphere. Generally, CFCs are chemically inert-the very reason for their wide industrial use. But high in the atmosphere they become exposed to ultraviolet (UV) rays from the sun, which break them into reactive compounds. These, Rowland and Molina argued, could react with and damage the layer of ozone in the stratosphere which absorbs and filters out most of the harmful UV solar radiation.
These fears were confirmed by the 1985 report of declining ozone concentrations over Antarctica in springtime. The "ozone hole" has subsequently appeared over the continent every austral spring, when the return of sunlight triggers the chemical reactions of chlorine compounds which destroy ozone.
Lovelock's response to the ozone alert is illuminating. Greens who see risks everywhere often fail to ask the critical question: how big a risk? To a man whose career was launched by a technique for unprecedentedly precise quantification, questions of scale are paramount. When Lovelock reported his global measurements of CFCs in 1973, he indicated that "the presence of these compounds constitutes no conceivable hazard."
Faced with the reality of the ozone hole, Lovelock now concedes that "this sentence has turned out to be one of my greatest blunders"-not because it was wrong, but because he didn't specify that he was referring only to the direct effects of CFCs as potential toxins, not to their ability to destroy ozone. For a time he remained sceptical that a slightly increased exposure to UV radiation was cause for concern, pointing out that life has adapted to a sevenfold natural variation in UV intensity from the equator to the poles, and to the paucity of knowledge about the effects of UV. He is similarly sceptical about the radiation hazards of nuclear power, admitting that "to my ecologist friends... these views seem like a betrayal." But to a man who used to scrape radium from old aircraft dials, radioactivity holds no fear. He has offered BNFL the use of his garden to store radioactive waste and believes a big expansion of nuclear power must be part of a strategy to combat global warming.
In the 1970s he opposed an absolute ban on CFCs. He even testified to the US congress on behalf of the chemical giant DuPont, which opposed such measures-against Rowland and Molina, whose work had initiated the concerns. Yet fears of the cancer risk from an ozone hole eventually led to an international agreement to restrict the production of CFCs: the Montreal Protocol, signed by 24 nations in 1987. The schedule for phasing out of CFCs was subsequently accelerated, and their build-up in the atmosphere is now slowing as a result. But because they last for many years, it will be some time before polar ozone depletion ceases. In the meantime, a hole has been observed over the Arctic, too. Ozone depletion will continue to make headlines, but it is a containable problem because the industrial countries are not addicted to CFCs in the way they are to fossil fuels.
Lovelock's position in the "ozone wars" has left no rancour. When Rowland and Molina won the Nobel prize in 1995 for their work on ozone depletion, Rowland acknowledged how Lovelock's detector initiated the discipline of atmospheric chemistry: tracking reactions between tiny amounts of gases in the atmosphere.
Lovelock's interest in the planetary environment had led to an invitation, in 1961, to join NASA's scientific team for the first lunar mission. He went west eagerly, joining the Mars programme to help develop instruments which would search for signs of life on the planet's surface. But he was unimpressed: "All they could think of was sending the kind of equipment they had in their own labs, automated on a robot, taking soil samples... and seeing if they grew micro-organisms. I thought this was crazy."
None the less, this was essentially the strategy followed when NASA sent its Viking lander spacecraft to Mars in the 1970s. The missions found no signs of life-and an even harsher environment, strafed with UV, than had been anticipated. Lovelock saw the Viking plans as prosaic. If life exists on Mars, he argued, it will leave its imprint in the atmosphere. The atmosphere of Earth is strongly conditioned by the totality of living organisms on the planet-the biosphere. Its high oxygen content-about 21 per cent-comes from plants, which take in carbon dioxide and expel oxygen as waste. The relatively minor but easily detectable levels of carbon dioxide and methane are also partly the products of life processes.
The blend of Earth's gases is not an equilibrium mixture-not one which has settled into a steady composition over billions of years. On a dead planet, in contrast, the atmosphere is more or less equilibrated. Life maintains the out-of-equilibrium terrestrial atmosphere by reprocessing, rearranging and recycling its components. This was brought home to Lovelock when analyses of the atmospheres of Mars and Venus showed them both to be more or less equilibrated, dominated by carbon dioxide.
Thus life proclaims itself in the blanket of gases surrounding a planet. Lovelock proposed that, to look for life on Mars, NASA should seek evidence of slight disequilibrium between the composition of the atmosphere and the planetary surface. Conditioned by science-fiction images of robot explorers, NASA scientists found this a bizarre idea, and it was never seriously adopted as the basis for a Mars mission.
But it was from these ideas that the Gaia hypothesis emerged. The Earth's temperature is regulated by greenhouse gases in the atmosphere: substances which, although present in only small amounts, trap solar heat rather than letting it radiate from the planet back into space. These gases include carbon dioxide, methane, and nitrous oxide, all from living organisms. The Earth is about 33oc warmer than it would be without them.
So, if living organisms decisively affect the composition of the atmosphere, and the atmosphere determines the planetary climate, then life on Earth has the potential to influence the conditions in which it grows. Lovelock began to suspect that the biosphere was capable of maintaining astonishing climate stability in the face of changing circumstances.
Carl Sagan, whom Lovelock met at NASA, was one of his more constructive critics. "He didn't entirely agree with my ideas for planetary life detection, but they did ring a bell with him." Sagan pointed out that since the formation of the solar system 4.6 billion years ago, the sun has become about 25-30 percent hotter. This is a great change-yet there is no sign that the Earth's climate has followed suit. Despite appreciable fluctuations in global mean temperatures-during the ice ages, for example-there is no sign in the geological record of steady global warming which parallels the sun's. Lovelock wondered whether the changes in solar output have been compensated for by changes in naturally generated greenhouse gases throughout the planet's lifetime, so as to keep the average temperature steady.
Most atmospheric scientists, Lovelock says, took the view in the 1960s that Earth had been blessed with an atmosphere uniquely suited to life, created through inorganic processes. They believed that oxygen, for example, came from the splitting of water molecules into hydrogen and oxygen, by sunlight. To Lovelock, "this view of the air as a product of wholly inorganic processes is the most magnificent nonsense... I do not know how it has managed to persist so long." In contrast, he proposed to put life centre stage in the story of our planet's environment.
Lovelock's simplest formulation of the Gaia idea is nothing more than that "the atmosphere [is] an integral part of the biosphere"-in other words, it is a product of the chemistry of life. This much is now uncontentious. But he was really proposing something more. He claimed that life can respond to climate change, thus maintaining the same steady state as that which keeps body temperature constant in the face of sun or snow. Such physiological constancy is known as homeostasis; it is in this sense that Gaia begins to look like a physiology of the planet.
To many greens, this suggests not only that the planet is alive but also that it is benevolent and sentient. Lovelock has never suggested this, and he phrases his interpretation cautiously. He first proposed the Gaia hypothesis in the early 1970s (with the aid of the biologist Lynn Margulis), but it was not until the publication of Gaia: A New Look at Life on Earth in 1979 that it became known outside the planetary science community. Only then did the trouble begin. Evolutionary biologists were scandalised, reading into the idea a suggestion of mystical communication between all living organisms. John Postgate, a leading microbiologist, called it "pseudo-scientific myth-making." One of its harshest critics was Richard Dawkins, who regarded the hypothesis as contrary to Darwinian natural selection. Worst of all were the suggestions that Gaia implied some kind of teleology, and so stood outside real science.
These criticisms pricked Lovelock because he recognised in them some validity. Although prepared to claim that "the biota interacts actively with its environment so as to maintain the environment at values of its own 'choosing,'" he had never intended Gaia to sound teleological-it is simply one of those ideas (like natural selection) to which teleological metaphors seem naturally to accrue. But neither had he provided a mechanism by which this seemingly miraculous behaviour of the biosphere could emerge.
In 1981 he found one. In "Daisyworld," Lovelock imagined a planet covered in black and white daisies. The black daisies absorb heat and light from the sun, and thus warm the planet's surface. The white daisies reflect more of the solar radiation, and thus have a cooling influence relative to the black daisies. Lovelock assumed that both have an optimal growth temperature, as real plants do. Because white daisies can stay cooler than black daisies, they thrive when the planet gets hot. Black daisies, on the other hand, prefer colder conditions, because they are better at capturing heat. Because of such differences, the flowers provide negative feedback, preventing the planet from getting too hot or too cold as the sun's output changes. Under a faint young sun, black daisies populate the planet and warm it up with such meagre solar heat as is available. As the sun heats up, the black daisies fry and the white daisies dominate, cooling the planet by reflection.
Daisyworld is a cartoon world, but it makes Lovelock's point that homeostasis can arise without purpose or communication. In response to criticisms that his model was simplistic, Lovelock demonstrated similar behaviour in more complex Daisyworlds: for example, with 20 species of daisy, from white through grey to black, or with rabbits which eat the daisies and foxes which eat the rabbits.
There are natural feedback processes on Earth which control climate. Ice sheets are like white daisies which thrive in the cold, not in warm conditions. If the Earth cools, ice sheets grow and reflect more sunlight, cooling the planet even further and thus accelerating the cooling. Some geologists now believe that the Earth has experienced at least one runaway cooling like this, leading to global freezing and almost pole-to-pole ice. Yet many climate processes involving the biosphere do exert a stabilising effect. For example, there is some evidence that plants grow faster when there is more carbon dioxide in the air, removing this greenhouse gas and so reducing its global warming effects.
But there is no guarantee that the net effect of such feedback will be stabilising. Indeed, Lovelock considers that most natural processes are now in positive feedback, exacerbating change. This, he says, reflects the "feverish" state of the planet during the warm periods between the ice ages. That is why, despite a strong aversion to alarmism, he senses danger in the greenhouse effect (which few now dispute) caused by carbon dioxide released from burning fossil fuels. "Maybe, if left to herself, Gaia could absorb the excess carbon dioxide and the heat that it brings," he said in 1988, when global warming was still just a hypothesis. But disturbing a "fevered" system can have unpredictable consequences-just as a person with severe hypothermia will die if put into a hot bath. Moreover, Lovelock points out, Gaia is not being left to herself-we are, for example, removing the carbon dioxide sinks of the tropical rainforest.
Daisyworld was a proof of principle; but Lovelock needed a real-world example of Gaia self-regulation. In the late 1980s he worked with climatologists Robert Charlson, Meinrat Andreae and Stephen Warren on the theory that marine algae can stabilise climate by controlling cloud formation. Some algae emit a gas called dimethyl sulphide (DMS). In the air, DMS reacts with oxygen to form sulphate, which aggregates into tiny dust-like particles. The sulphate particles absorb water vapour and help the formation of cloud droplets. The greater the amount of sulphate, the thicker the clouds and the more sunlight they reflect from their tops, cooling the surface below. Although there are other sources of sulphate particles on which cloud droplets can condense, DMS emissions from algae have an important effect on the cloudiness and climate of the oceans. The Gaian idea was that, in warmer conditions, the algae are more biologically active and so produce more DMS, generating cloud cover and counteracting the warmth.
Climate scientists set out to test this by measuring how DMS emissions from the seas, and cloud cover, vary with seasonally induced temperature changes. The observations were ambiguous; despite increasing understanding about how sulphur compounds are cycled between biosphere and atmosphere, they came up with no clear evidence either for or against this possible Gaian mechanism of climate regulation.
Nor have any other tests so far. Part of the problem is that the hypothesis is more like a world view than a scientific theory. "I know of no single and exclusive test that could prove or disprove the existence of Gaia as a living entity," Lovelock admits. This does not make the idea unverifiable; but support, if it exists, would have to be accumulated gradually.
Yet the objection of some evolutionary biologists is a more fundamental one (and biology today has a power of scientific veto-once the sole privilege of physicists). Dawkins considers the hypothesis an example of "bad poetic science"-a seductive metaphor coupled to a flawed idea. "It assumes," he says, "that individual organisms will sacrifice themselves for the benefit of the entire system and that's wrong." It is not clear that Dawkins has moved beyond his gut response to the half-formed idea of the 1970s; but the basic objection is valid. If organisms adapt only for short-term reproductive success, why should a climate-regulating biosphere emerge?
William Hamilton, one of the world's leading biologists and a long-term Gaia sceptic, was persuaded shortly before his death this year to pursue this question. One of his criticisms was that Lovelock's daisies could not adapt to different climate conditions. How might evolution reshape Gaia? With Tim Lenton, a Lovelock prot?, Hamilton considered whether there might be an evolutionary pay-off for algae which control cloud formation. Clouds create rising air masses, stimulating winds and ruffling the sea surface. Hamilton and Lenton suggested that algal spores released in wave spray and dispersed by winds enable them to propagate their genes elsewhere.
It remains unclear whether Gaia can be made to sit comfortably with Darwinism; but Lovelock recognises the importance of the attempt. For him, Gaia is most certainly not a deus ex machina. This openness to debate and interaction has softened sceptical biologists like Hamilton. All Lovelock now wants them to accept is that natural selection does not operate within a pre-imposed environment, but within one susceptible to alteration by life's handiwork.
Lovelock remains gallant to his critics, saying that they have helped him to refine his ideas. He says: "The battle between Gaia and the selfish gene is part of an outdated war between holists and reductionists. In a sensible world, we need them both." This is why he will never be the guru some greens want; for him, the holist/reductionist dichotomy misses the point. After all, the fashion for denouncing science as reductionist ignores many disciplines such as earth science, ecology, and even many areas of physics, within which the limitations of such an approach have always been recognised. Indeed, Lovelock regards the trend for referring to the study of the planet's environment as "earth system science" as a tacit assimilation of Gaian concepts. (Not that the system-level view is new. Lovelock acknowledges his debt to the 18th-century Scottish geologist James Hutton, who regarded the Earth as a super-organism. Leonardo da Vinci expounded the same idea, whose origins lie deep in antiquity.)
Lovelock's work on Gaia over the past 30 years has been conducted almost entirely as an independent scientist, and he cannot imagine it any other way. "As a university scientist I would have found it nearly impossible to do full-time research on the Earth as a living planet... I work at home, supporting myself and my family by whatever means come to hand. It is a delightful way of life that painters and novelist have always known about." He recently told the Big Issue that the next Einstein or Darwin might be a scientist on welfare-"you don't have to be rich, you don't have to have piles of equipment, and I'd love it if you didn't have to have qualifications either."
Lovelock shows no slackening of vigour. He celebrated his ninth decade by walking England's southwest coastal path from Poole to Minehead, and the prospect of a rapprochement between Gaia and neo-Darwinism is a new stimulus. But this is a tough task, which he is now devolving to others. "I have no belief in a hereafter," he says, "but it is comforting to think that... my destiny is to merge with the chemistry of our living planet."
Lovelock sees this as more than simple materialism: "We can put our trust, even faith, in Gaia, and this is different from the cold certainty of purposeless atheism or an unwavering belief in God's purpose... Gaia... offers a world view for agnostics"-one in which we can believe that we are part of something larger. But it is not clear to what manner of God or beast we would be entrusting our faith. The Gaia hypothesis, like the Bible, offers such latitude of interpretation that one can easily shape it to one's prejudices-not usually something to recommend in a theory. To greens, it can be a nurturing mother substitute. To polluting industries it says that, far from being fragile, nature is robust, able to absorb change. To those worried about eroding biodiversity, it reveals the interactive nature of the biosphere. At least this multiplicity of interpretations will save Gaia from dogma-something which has always been foreign to its creator. n
