The Revenge of Gaia by James Lovelock

A lot of hot air comes from sacred cows

So says James Lovelock in The Revenge of Gaia. What brought on this apocalyptic vision? Actually, it was the prospect of a wind farm being built near his house in Devon. "It was this that awakened my fury, and made me fully aware of the coming crisis of global heating," he writes. It's one of many "hang on a minute..." moments in a book that is to be both argued and agreed with. But Lovelock's vast learning, crisp and energetic writing, and original thinking mean that every disagreement is a prompt to become better informed and clearer-thinking about climate change.

Lovelock's Gaia hypothesis, formulated in the late 1960s, has it that life on earth regulates the climate, so as to keep conditions favourable for itself. He noticed, for example, that ocean algae release a sulphur compound that makes clouds form. Warm, sunny weather means more algae, which make more clouds, which reflect sunlight and cool the earth.

Many mainstream biologists dismissed Lovelock's ideas, because they seemed incompatible with what we know about evolution, namely, that it has no foresight and no incentive to promote planetary health. Gaia theory, however, is now, although not proven, at least fairly respectable in academic circles, where it trades under the less emotive name of Earth system science. This is one of a number of disciplines seeking to understand how ordered, persistent structures and behaviour can arise in large, complex systems, whether they are living, like an ant's nest, purely physical, like Jupiter's great red spot, or both, like the Earth system. Lovelock still writes about Gaia as having the goal of regulating the climate, which I think is wrong, even as a metaphor. But he is right to highlight the extent to which life does not just adapt to its physical environment, but shapes it too.

Climate change is an experiment in Gaia theory. At first glance, Gaia-tinted thinking seems comforting. Most plants will grow more in air enriched with carbon dioxide. So perhaps increased plant growth on land and sea will absorb carbon dioxide and buffer the climate. But the evidence so far gives few grounds for such optimism. Nobody knows how the living world will respond to climate change, and how this will in turn change the climate. But the answer to how much plant growth will increase in the global greenhouse, and how much extra carbon the world's forests and plankton can store seems to be "not much". There are also weird things going on that no one suspected: last month, Nature published a paper showing that 10-30 per cent of the world's methane emissions - a greenhouse gas many times stronger than carbon dioxide - come from plants. Not very Gaian...

Earth's climate does not change smoothly. It seems to have different stable points, that represent ice ages, or an interglacial period like we are in now, or still hotter phases - when dinosaurs roamed in the Cretaceous period, about 70 million years ago, there was no ice at the poles. The climate is like a boulder in a valley-bottom; its tendency is to stay put, and it rolls back from a small shove. But push it up to the top of a ridge, and it tumbles into the next valley, and a different stable state.

If emissions continue at anything like their present rate, Lovelock argues, we will push the climate boulder into a valley similar to the Eocene, 55 million years ago, when the world was more than 5°C hotter than it is now, and "the land and ocean ... were barren". This, says Lovelock, would be the Earth's way of letting humanity know it was no longer welcome; billions would go hungry. Such a temperature rise is at the extreme end of current climate-change scenarios, but so is the warming experienced in the past couple of decades. And a temperature rise of only 2°C from current conditions would probably trigger many of the changes, such as the loss of tropical forests, that Lovelock fears.

To avoid this hellfire, says Lovelock, we must stop burning fossil fuels and stop destroying the natural habitats that sustain us. Short term, we should meet our electricity needs through nuclear power. Long term, we should look to nuclear fusion to generate our power, synthesise our food from chemicals rather than grow it, and perhaps explore exotic measures such as using giant mirrors to reflect sunlight and cool the earth. He sees most of environmentalism's sacred cows - sustainable development, organic farming, the hated wind farms - as cosmetic, inadequate for meeting society's needs or saving nature.

On a planetary scale, Lovelock is right that nuclear waste is a less dangerous pollutant than carbon dioxide. With his background in medical research and engineering, it's not surprising that he gravitates towards technical solutions to climate change - he has advocated atomic power for decades. But it's not a straight choice between coal and uranium. Some researchers calculate, for example, that investing in saving energy gives a far better return, in terms of emissions saved for each pound spent, than any form of power generation. Also crucial is ending the perverse subsidies that governments give to those destroying the environment, making polluters bear the costs of their pollution, and recognising the value of the services provided by wild ecosystems in cleaning our air and water, and so on.

Plus there's the possibility that, even if the technology is right, people will do the wrong thing with it. In his 1979 book Gaia, Lovelock voices the hope that industrial farming will usher in "a wonderfully harmonious period in the relationship between man and his environment, reminiscent of the heavenly countryside of southern England not so long ago". In The Revenge of Gaia, he writes that it was about this time that he moved from Wiltshire to Devon, "to escape the bulldozers that were destroying the Wiltshire hedgerows and meadows". His continuing belief that we can techno-fix our way out of environmental crisis seems odd, given modern technology's relentless drive to spoil his view.