James Lovelock has complained before about the lack of urgency with which governments have reacted to his warnings about the future of the planet, but he must be pleased with last week's news. The strong indication that the Prime Minister supports the building of a new generation of nuclear power plants in order to cut our greenhouse gas emissions comes only 18 months after Lovelock's bombshell of an article in The Independent, which launched a fierce debate among scientists and green activists. It was the breaking of the great green taboo.
In it he declared that there was no viable alternative to nuclear energy if we were to alleviate the already dire consequences of climate change which will become obvious within a few decades. Lovelock believes that the widespread fear of nuclear energy is ignorant and irrational: "What at first was proper concern for safety has become a near-pathological anxiety."
Much of the blame for this, he said, belongs to the news media, television and film industries and green lobbyists who have demonised anything to do with nuclear power: "No source of power is entirely safe, but compared to nuclear power the dangers of continuing to burn fossil fuels as our main energy source are far greater and they threaten not just individuals but civilisation itself."
In the public mind Lovelock is the green guru, the proposer of the Gaia hypothesis that the planet functions like a single organism. But although he is one of the most famous scientists on the planet and one of the creators of our current environmental consciousness, he has often been considered a maverick by the green movement.
For him it's a question of scientific rigour: "Their hearts are very much in the right place, but they often get the science wrong, and you can't really be a green without being involved with science. Fifty years ahead when the problems of the greenhouse effect really hit us hard, somebody is going to point a finger back at the greens and say, if we had nuclear power we wouldn't be in this mess now."
Though his intervention into the nuclear debate is recent, he has long believed in this green heresy. In 1988 he wrote, "I have never regarded nuclear radiation or nuclear power as anything other than a normal and inevitable part of the environment. Our forebears evolved on a planet-sized lump of fallout from a star-sized nuclear explosion, a supernova that synthesised the elements that go to make our planet and ourselves."
Such independence of mind has been a distinguishing quality throughout his long and extraordinary career. Science was an early passion. He was born in 1919 and grew up in Brixton. He began to know and love science through visits to the Science and Natural History Museums in South Kensington and the science fiction of H G Wells and Jules Verne.
At weekends his father took him to the countryside where he grew to appreciate the natural world. His father, though poorly educated, was intelligent and curious and knew the common names of almost every species of plant, animal or insect.
"I learnt from him a respect for living things," Lovelock said. "He had the mind of an ecologist and recognised the interconnection between the plants and insects." His schoolfriends gave him the nickname of "The Mad Scientist", but his grammar school did not recognise his abilities.
Because his family wasn't wealthy enough to send him to university, on leaving school he became an apprentice with a firm of consulting chemists and studied chemistry in the evening at London University. "The hands-on experience I gathered as an apprentice was a priceless gift that has served throughout my life as a scientist. I grew to regard accuracy in measurement as almost sacred."
When the war came, London colleges were closed, but Lovelock's first-year results were good enough for him to obtain a scholarship to study full-time at Manchester. One month after his arrival he was called to his professor's office and accused of cheating.
"I was amazed and confused but he went on, 'Look at the results of your gravimetric analyses. You have reported exactly the concentrations of bromide ion in the two solutions you analysed. You may not know it, but students almost never get the right answer to gravimetric analyses, and certainly never twice running. There is only one possible explanation: you must have looked up the answers in the class book that the demonstrator foolishly left in the lab.' By then he was in full flood. It took nearly 30 minutes to convince him that I was, after two years' apprenticeship, a professional at this analysis. It was for me a routine task and one I expected to get right. The exchange left us both wondering what university training was really about."
Although exempt from military service as a student, Lovelock typically insisted on registering as a conscientious objector. At the time he would have described himself as a socialist, though later he became a social and an economic conservative and a great admirer of another chemistry graduate, Margaret Thatcher.
After graduating and taking a PhD in medicine, he took a job at the National Institute for Medical Research in London, where he spent the next 20 years. Here in 1957 he invented and developed the electron capture detector (ECD), a simple, small device which became an invaluable tool in environmental research through its ability to detect infinitesimal amounts of chemicals in the atmosphere and elsewhere.
Its first use was in the practical analysis of pesticide residues in foodstuffs. When it was realised that pesticides such as DDT were distributed across the world, that they were in the fat of Antarctic penguins and in the milk of nursing mothers in Finland, it was the first recognition that pollution was no longer just a local problem. Humans were affecting the environment on a global scale. The data about the distribution of pesticides and their poisonous effect on birds of prey led Rachel Carson to write her seminal book The Silent Spring.
Lovelock's own researches in the mid-1960s with the ECD led to the discovery of the rising levels of chlorofluorocarbon gases in the atmosphere and the consequent and potentially dangerous depletion of the ozone layer.
In 1961, through his brilliance as an inventor, he was asked to join Nasa to develop sensitive instruments for the analysis of extraterrestrial atmospheres and planetary surfaces. In response to the questions "Is there life on Mars?" and "How do we test for it?", Lovelock came up with ingenious solution of simply examining the composition of its atmosphere from Earth using infrared astronomy, because any Martian lifeforms would be obliged to make use of it (and alter it).
He discovered that the atmosphere was in a stable condition close to its chemical equilibrium, with very little oxygen, methane or hydrogen, but with an overwhelming abundance of carbon dioxide. To Lovelock, the stark contrast between the Martian atmosphere and chemically dynamic mixture of that of the Earth was strongly indicative of the absence of life on the planet.
The top-down view of Earth's atmospheric chemistry was for him a revelation. The analysis revealed the atmosphere as a gas mixture like that of the intake manifold of an internal combustion engine: oxygen and combustible gases mixed. Also, the chemical composition of the atmosphere was stable for long periods.
One afternoon in 1965 at the Jet Propulsion Laboratory in California the thought came to him in a flash that such constancy required the existence of an active control system, involving the whole planet and all the life on it. The Earth seemed to operate as a superorganism. He discussed this idea with his friend, the novelist William Golding, who suggested the name Gaia, after the Greek goddess of the Earth.
After developing the concept of Gaia with the biologist Lynn Margulis, he published some articles in the 1970s and eventually a book, Gaia: A New Look at Life on Earth, in 1979. It was aimed at the general reader and became a bestseller, embraced by radical environmentalists, goddess worshippers and New Age philosophers - though many scientists were dubious about the theory and repelled by the quasi-spiritual overtones.
Lovelock admits that it would have had a better reception among scientists without the Gaia label, but he was eager for the widest possible audience for the book and intent on raising awareness of the environmental threat to the planet. "Gaia embraces the intuitive side of science as well as the rational. It makes the theory a personal presence, more accessible to the non-scientist." He later backed off from some of the more extreme claims - that the Earth is a consciously living organism, for example: "Nowhere in my writings do I express the idea that planetary self-regulation is purposeful, or involves foresight or planning by the biota."
Today, the "weak" Gaia hypothesis that organisms on the Earth have radically altered its composition and that the biosphere effectively acts as if it is a self-organising system to keep an equilibrium that is broadly conducive to life has a much wider acceptance among scientists. Lovelock says it has been a bruising battle.
"I've devoted most of my working life to Gaia. Most of my research has been self-funded. I could never get a grant. No surprise, though. If you start any large theory, such as quantum mechanics, plate tectonics, evolution, it generally takes about 40 years for mainstream science to come around. Gaia has been going for only 30 years or so."
And he remains optimistic about the future despite the ravages he expects to caused by global warming. "Human beings are very tough and will survive - have survived for at least a million years. Civilisations, though, are fragile. Thirty or so have come and gone in the past 5,000 years. And there's no reason to assume that ours is permanent."
A Life in Brief
BORN James Ephraim Lovelock, 26 July 1919, in Letchworth, Hertfordshire, son of Tom and Nellie Lovelock.
FAMILY Four children by his first wife, Helen; now lives with second wife, Sandy, an American scientist.
EDUCATION Studied chemistry at London University and the University of Manchester; in 1948, received a PhD in medicine from the London School of Hygiene and Tropical Medicine.
CAREER Worked 20 years at the Institute of Medical Research, then for Nasa at the Jet Propulsion Laboratory in California. Since the mid-1960s he has been an independent scientist. Published Gaia: A New Look at Life on Earth in 1979.
HE SAYS "I hope that I have shown that science can still be a vocation, not just a career. Something that can even be done at home, in the way an artist or novelist works."
THEY SAY He is the most important and original scientific thinker in the world today." - John Gray, Professor of European Thought at the London School of Economics