The Vanishing Face of Gaia, By James LovelockHe Knew He Was Right, By John Gribbin and Mary Gribbin

It is one of the supreme ironies of intellectual and scientific history that a profound new understanding of the Earth should come along just in time to forecast its end.

Perhaps not the end of the planet itself, but certainly the end of much of the life that has flourished upon it, and of human society: to foresee this has become in the last few years the role of the Gaia theory, the compelling idea of the British scientist James Lovelock, that our world behaves like a single organism, and possesses a planetary-scale control system which keeps the environment fit for living things.

Forty years ago when he worked it out, Lovelock named the system after the Greek goddess of the Earth, creating in many people's eyes a new Earth Mother, benevolent and all-wise, watching over us. Now he believes that our abuses of the planet are making this system work against us, and that this means climate change, the greatest threat the human world has ever faced, will be impossible to solve, and will soon destroy civilisation as we know it, perhaps within the lifetime of a person born today.

Can there ever have been such a double leap inside the head of a thinker? First, to conceive of an entirely new way of looking at life on Earth, the first since Darwin, with the revolutionary insight that it is living things themselves, interacting with their environment, which maintain the stable conditions we need to exist – stable air temperature, stable composition of the atmosphere, stable salinity of the sea.

To have that accepted by mainstream scientific opinion involved a struggle of many years – it is widely accepted now – and most of us might want to rest on our laurels when it was done. But then, half a lifetime later, to become convinced that it is this very system which means we will not be able to escape the terrible consequences of our own despoiling of the biosphere with the waste products we are pouring into it, greenhouse gases above all. Well! These are two succeeding insights, each enormous in scale; they would normally belong to two successive and enormous intellects; yet they followed each other in the head of the same man.

He will be 90 in July. There is no sign of diminution, however, of James Lovelock's intellectual powers or his energy, no slipping in the logic of his thinking, the logic which led remorselessly from his proclamation of Gaia the protector, to the role he plays now as ringer of the planetary alarm bells, and which he takes up once more in his new book. The Vanishing Face of Gaia follows on from the 2006 book in which he announced the danger, The Revenge of Gaia, and if the second goes over some of the same ground as the first, it does so with enormous force and lucidity.

At the heart of Lovelock's concern is feedback, that feature of cybernetics, or the control of systems, in which a part of the output of a process returns to affect the input; his key insight in the conception of the Gaia theory was that the Earth, or the "Earth System", was maintained in a stable state by a whole series of feedback mechanisms. They were benevolent; but our stressing of the system, Lovelock is convinced, means they will now turn against us and combine to amplify the changes to come.

A perfect example is the melting of the Arctic sea ice. As it disappears, the bright surface which reflected back much of the sun's warmth goes with it, leaving dark ocean, which absorbs more heat, which leads in turn to more melting, and so on. The Vanishing Face of Gaia makes a gripping, convincing and indeed terrifying case that this process, this moving of the whole Gaian system against us, will make catastrophic global warming impossible to stop, and that the end of our current way of life is far closer than almost anyone imagines.

If you are coming to Lovelock fresh, in picking it up, you will quite simply never have read a book like this. Lovelock believes that the UN's climate scientists (who were accused of exaggerating by the Bush administration) have in fact grossly underestimated the speed at which climate change is happening, and that what we must do now is concentrate on survival. His recipes are as controversial as his forecasts are unpalatable, in particular, his urging us to abandon renewable energy schemes as a waste of time and concentrate on nuclear power.

And yet the man behind this apocalyptic message has been led there solely by logic and a unusually fertile mind; in his personal life, as John and Mary Gribbin make abundantly clear in their absorbing new biography, Lovelock is the most genial and common-sense of characters, a boy from Brixton whose endless curiosity led him to become one of the 20th century's leading inventors of scientific instruments, before stumbling on something far greater. Now, as he comes up for his tenth decade, he has another remarkable project in mind: to see the earth as he has never seen it before. Richard Branson is developing a rocket plane to take passengers to the edge of space, and has promised Lovelock a free ride. His final ambition is to behold Gaia from above, in all her glory: let us wish him a fervent bon voyage.

Penguin are issuing the two books together, which is a marketing ploy, but in this case a worthy one, as the Gribbins' enormous scientific knowledge and clarity of expression make equally comprehensible Lovelock's initial Gaian vision, and the frightening conclusion to which it has now led him.

Michael McCarthy is environment editor of 'The Independent'. His book, 'Say Goodbye to the Cuckoo', will be published by John Murray on 2 April

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