Have we killed off nature?

One morning in late autumn 10 years ago I sat down to write a column to express a great sorrow. It began with the view from my desk, painting in the vivid sky and sea, the low sun gilding islands and wavetops. I wanted to make a point about the timelessness of the seascape, its dependable, seasonal and somewhat ruthless beauty. How upsetting it was not to trust it any more!

I had been reading Bill McKibben's The End of Nature, a whole issue of New Yorker magazine, and later a book. It brought home to me a deeper meaning of global warming - then still a matter about which scientists could disagree. There is no future in loving nature, said McKibben, because the world outdoors is no longer independent of us: it has become another product of our economy and lifestyle. "The wind still blows," he wrote, "but not from some other sphere, some inhuman place."

anchor for the human psyche, a sort of lofty guarantee. Yes, there were storms and floods, but not impossible storms, or not in outrageous numbers, or the historical human fabric could not exist. Such a reassuring belief, as McKibben made us realise, is no longer tenable. "Uncertainty itself is the first cataclysm and perhaps the most profound."

Ten years on, the only certainty is that the phenomenon is real: the global warming of the past 25 years is our fault. And the latest draft report of the UN's Intergovermental Committee on Climate Change presents an even more perverse - and literally chilling - possibility: that north-west Europe will lose the Gulf Stream (or North Atlantic Drift), causing temperatures to plummet by 5 degrees Centigrade or more.

The hypothesis has been that melting Arctic ice will dilute the saltiness of surface water in the North Atlantic and so stop it sinking to the ocean floor. This is the circulation mechanism that drives the two massive "pumps", one in the Greenland Sea and the other in the Sea of Labrador, which draw warm water north from the Gulf of Mexico and send cold water back along the bed of the ocean. The first evidence that this could be happening has now come from research into waters off Shetland, the Faroes and Norway.

Reaction to all this depends upon your world view. There are those - probably still a majority - who feel the human race is essentially outside of the natural world and superior to it. They find human genius in both contriving non-stop change and adapting to it. With technology to solve the problems, "progress" need never cease.

Another kind of people sees itself as just one species of the natural world, the self-regulating superorganism of James Lovelock's Gaia. They are not surprised by the idea that the human race may have - or should have - ecological limits, or particularly shocked to think the Earth could carry on perfectly well without us. They would like to live as if nature had its own intrinsic worth.

The "deep ecology" activists who were among those causing ructions at the World Trade Organisation conference in Seattle last week are on the radical wing of such a view. Along with specific concerns about logging and animal rights, they see the free-trade policies of transnational capitalism as an enemy of human diversity - of small, regional economies and minority cultural traditions.

They are heirs to the ideas of Arne Naess, the Norwegian professor who coined the term "deep ecology" 25 years ago. His principles were in tune with American Green thinkers such as Aldo Leopold and Rachel Carson, and have helped to shape the "eco-ethics" platform shared by a growing number of European scientists. A central conviction is that human populations must be reduced to the carrying capacities of the ecosystems in which they live - a discipline that applies to every other species on Earth.

The "Earth First!" activists of America's deep ecology movement are apt to put things more crudely. Human overpopulation is a cancer on the planet, they say, and AIDS may be Gaia's way of trying to control it. Some commentators find this a "grotesque notion", often expressed with unsavoury relish. But homo sapiens is the only species that interferes with natural processes of disease and death, without a commensurate control of birth-rate, and the appearance of new viral epidemics seems a certainty for the coming century.

Meanwhile, 10 years on towards the end of nature, I look out to an ocean that still seems only modestly menacing. But rain has been falling in great lumps on Thallabawn. In the four weeks from the end of October, half the days had virtually no rain. But in the rest there were four days which, taken together, poured 204 mm into our raingauge - about eight inches of rain. "T'aint nacheral", but all of a piece with the warm, wet and windy winters the climate models predict.

That is, of course, unless the Gulf Stream pump fails us, when blizzards and ice storms will be more the mark.

I await with satisfaction the return of the real weather forecasters to our television set. Only people to whom the weather didn't really matter could have supposed that "virtual" presenters, no matter how young and affable, could muster the credibility of the genuine article. When a really bad storm is heading in from the Atlantic, I want to read a well-trusted Met Eireann face for every nuance of what we're in for.

Corncrake update: sad to report that the bird being cared for on Inishbofin, as reported last week, keeled over and died.