"When I was young, chemistry had soul. Things went bang, and flash. There were wonderfully coloured lights, and the most amazing assortment of smells, some of them wonderful, some of them absolutely disgusting. All that has gone now. The Health and Safety people won't allow it. No wonder children don't want to study science any more." James Lovelock sits in his study by a river in Devon, watching the ruin of the world. In front of him, on a large flat panel monitor, there is a climate map of the northern hemisphere, updating constantly with evidence of climate change. All around Greenland there is unfrozen water; though it's early December the North West passage has only just closed.
The room is lined with books and instruments, some of which he has built himself. Behind the monitor, on a window ledge, is what appears to be a little aluminium model of some insect antenna. In fact, it is his most famous instrument, the electron capture detector, an extraordinarily sensitive device, which showed, in the 1960s, that the atmosphere was full of pesticide residues, and in the 1970s that it was full of CFCs. Both discoveries were hugely important to the Green movement; still more important, perhaps, was his Gaia hypothesis - the belief that the Earth and its life forms together constitute a single life form, which has maintained itself for more than three billion years.
Gaia seems to offer a rational basis for the religious feeling that inspires some environmentalists; but it is not a cuddly deity. Most life forms - for much of Gaia's life, all of them - have been bacteria; and the history of mass extinctions suggests the life of anything larger than a bacterium will always be precarious. "If there were a nuclear war, and humanity were wiped out, the Earth would breathe a sigh of relief. It doesn't mind radiation. From the planet's viewpoint, it could say 'that was a rotten experiment. I'm glad it's over.' Gaia has a destructive side, like Kali," says Lovelock.
His strong support of nuclear power, though, made him a heretic to many Greens. Nuclear power, he says, is much safer than the alternatives, and desperately needed to help us survive the effects of global warming. "To save ourselves we need to have a proper nuclear programme. The Greens don't seem to understand that without electricity, civilisation would collapse. Just imagine London without electricity. Within three weeks it would be like Darfur." He has no time for the long-term arguments about waste and safety: in a crisis, you do what you need to survive. "We are like paramedics to the planet. We just have to stabilise things."
He thinks it is a ludicrous presumption to suppose that we can save the world. Serious climate change is now inevitable, whatever we do: by the middle of the century, he says, the Arctic icecap will have gone; by the end of it, the rain forests will have disappeared too, to be replaced by desolation. The Earth's temperature will have risen by 8C, as it has before, and it will probably stay there for another 200,000 years.
"In a sense, since we are part of the whole system, you can say we are the consciousness of the planet. We are part of it, we can never consider ourselves as something separate. To think we could be its stewards is grotesque. We will be struggling against it. We've got to make peace while we're still strong enough to make terms, and not just a rabble. I see Kyoto as like Munich. It's an attempt to buy time before the real struggle starts." This attitude was shaped by his experience in the second world war, as a government scientist and conscientious objector, and by the struggles of his early life.
He was born in Brixton in 1919, to working-class parents determined their son should better himself. They ran an art gallery on Brixton Hill in their spare time, an enterprise somewhat before its time. The young Lovelock found refuge in the basement of the Brixton library, where the science books were kept. From the age of eight, he would "find great fat tomes of chemistry and take them home to read". He still has the Merck Index, a boxy, well-bound reference book, with thumb holes down the side, describing the history and qualities of almost all the chemicals so far discovered or made. "You can get it on CD now, of course: a sign that [the index in book form] is coming to the end."
When he takes it down to talk about fluorine, it is possible to understand how chemistry became for him, as for the young Oliver Sacks, a kind of grammar of the universe. Lots of children will leap into great heaps of apparently dry facts with as much delight as if they were drifts of autumn leaves, but why chemistry? In part, he didn't like the other sciences. Mild dyslexia made maths difficult, which ruled out physics, and biology was badly taught: "I had no desire to carve up frogs." Part was rebellion against his parents: "My mother and father were very much in the arts world. Their desire for me was that I should become interested in art, music, all the civilised things of life. I didn't like it. I soon found the Science Museum. So on Sundays, they would go to the V&A and I would go to the Science Museum."
After serving an apprenticeship in a chemical supplies firm in Kensington, he went to Manchester University and from there to the Medical Research Council, where he worked on everything from the prevention of colds to the freezing of sperm. He may have been the first man to use microwaves deliberately for heating frozen things, in his case hamsters. Lovelock's team froze whole live hamsters slowly, then used the microwaves to restore them to life by thawing their hearts before the rest of the animal. This proved, among other things, that memory is preserved in the way that brain cells grow together, since a hamster that had learned to run in a maze would retain the knowledge even after being frozen and resuscitated. But in the early 1960s he left this well-paid, pensionable post to become a freelance or independent scientist, even though he had four children, the youngest brain-damaged, and a wife with multiple sclerosis. His trust in his own judgment is so absolute that when I asked if there were any books that had changed the way he saw the world, his first reply was: "I think I'm so obstinate that I have never read such a book."
Far more scientists should work independently, as he does, he thinks. The reason they don't is just lack of courage; but Lovelock had been working in America, on the space programme, and told himself he lived next to a huge waterfall of money, and all he had to do was to catch a little of the spray.
It worked. By a mixture of inventions and consultancies, he was able to do the work he loved while still supporting his family and living in the countryside that he thinks is vital for surival.
His inventions kept him solvent. Gaia made him famous, and brought him his second wife, Sandy, a much younger American whom he met in a coup de foudre at a conference for "Global leaders" in Oxford while his first wife was dying, and who had read his first book on Gaia. The two seem constantly aware of each other, turning together like birds in a flock.
The gadgets and tools along the walls of Lovelock's study are essential to his thought processes. For as long as he can remember, he has used his hands as well as his mind. That is why the loss of noisy, smelly, sensual chemistry matters so much to him. "There is a hand-to-brain link which is essential in science, and that is how the youngsters are losing out. Imagine being shown a skateboard or a bicycle and then being told that you can't play with it."
He gestures at the climate map on the monitor in front of him: "I often think of the conscious mind as a display screen. The real processing goes on elsewhere. Just imagine trying to put a Vermeer on to the screen of a mobile phone. If you don't get your hands involved in what you're doing it doesn't somehow go into the unconscious properly.
"Science is far more expensive than it ought to be because most scientists don't make their own instruments. They could make them, but they don't. If you're forced to do it yourself and you then make it specifically for that job, [it is] probably better than a commercial one. The awful thing is that they have no idea how commercial ones work, whereas if you make your own you have to understand."
His appetite for life remains gargantuan. "One of the awful things I find today is that young people come to me and ask if there is any hope. Of course there's hope. At the moment, we are just waiting as we were in the 30s, when everyone knew war was coming but no one knew what to do about it. The moment the war started, we knew that the prospect was pretty awful, but there was a wonderful sense of purpose. There were no consumer goods, and food was strictly rationed. We never considered that time hopeless. When climate change gets bad, then there will be excitement, and that's the payoff. As Crispin Tickell said, what we need is leadership - and disaster."