Why Gaia is wreaking revenge on our abuse of the environment

With anyone else, you would not really take it seriously: the proposition that because of climate change, human society as we know it on this planet may already be condemned, whatever we do. It would seem not just radical, but outlandish, mere hyperbole. And we react against it instinctively: it seems simply too sombre to be countenanced.

But James Lovelock, the celebrated environmental scientist, has a unique perspective on the fate of the Earth. Thirty years ago he conceived the idea that the planet was special in a way no one had ever considered before: that it regulated itself, chemically and atmospherically, to keep itself fit for life, as if it were a great super-organism; as if, in fact, it were alive.

The complex mechanism he put forward for this might have remained in the pages of arcane geophysical journals had he continued to refer to it as "the biocybernetic universal system tendency".

But his neighbour in the village of Bowerchalke, Wiltshire, the Nobel Prize-winning novelist William Golding (who wroteLord of The Flies), suggested he christen it after the Greek goddess of the Earth; and Gaia was born.

Gaia has made Professor Lovelock world famous, but at first his fame was in an entirely unexpected quarter. Research scientists, who were his original target audience, virtually ignored his theory.

To his surprise, it was the burgeoning New Age and environmental movements who took it up - the generation who had just seen the first pictures of the Earth taken by the Apollo astronauts, the shimmering pastel-blue sphere hanging in infinite black space, fragile and vulnerable, but our only home. They seized on his metaphor of a reinvented Mother Earth, who needed to be revered and respected - or else.

It has been only gradually that the scientific establishment has become convinced of the essential truth of the theory, that the Earth possesses a planetary control system, founded on the interaction of living organisms with their environment, which has operated for billions of years to allow life to exist, by regulating the temperature, the chemical composition of the atmosphere, even the salinity of the seas.

But accepted it is, and now (under the term Earth System Science) it has been subsumed into the scientific mainstream; two years ago, for example, Nature, the world's premier scientific journal, gave Professor Lovelock two pages to sum up recent developments in it.

Yet now too, by a savage irony, it is Gaia that lies behind his profound pessimism about how climate change will affect us all. For the planetary control system, he believes, which has always worked in our favour, will now work against us. It has been made up of a host of positive feedback mechanisms; now, as the temperature starts to rise abnormally because of human activity, these will turn harmful in their effect, and put the situation beyond our control.

To give just a single example out of very many: the ice of the Arctic Ocean is now melting so fast it is likely to be gone in a few decades at most. Concerns are already acute about, for example, what that will mean for polar bears, who need the ice to live and hunt.