Few scientists have elicited such equivalent heaps of praise and criticism as James E. Lovelock, the British chemist, inventor and planetary diagnostician who has long foreseen a clash between humans and their planet. His work underpins much of modern environmentalism. The electron capture detector he invented in the 1950 s produced initial measurements of dispersed traces of pesticides and ozone-destroying chlorofluorocarbons, providing a foundation for the work of Rachel Carson and for studies revealing risks to the atmospheres protective ozone layer.

His conception in 1972 of the planet s chemistry, climate and veneer of life as a self-sustaining entity, soon given the name Gaia, was embraced by the Earth Day generation and was ridiculed, but eventually accepted (with big qualifications), by many biologists.

Dr. Lovelock, honored in 1997 with the Blue Planet Prize, which is widely considered the environmental equivalent of a Nobel award, has now come under attack from some environmentalists for his support of nuclear power as a way to avoid runaway “global heating” — his preferred alternative to “global warming.”

In his latest book, “The Revenge of Gaia: Why the Earth Is Fighting Back — and How We Can Still Save Humanity” (Perseus, 2006), Dr. Lovelock says that any risks posed by nuclear power are small when compared with the “fever” of heat-trapping carbon dioxide produced by burning coal, oil and other fossil fuels.

In a review in the current edition of American Scientist, Brian Hayes, a senior writer, says the book contains “something each of us can admire and embrace, and also something each of us can disdain or ridicule.” He adds, “For me it’s pretty nearly an even mix.”

Opponents of nuclear power have started a counteroffensive to Dr. Lovelock s call for a new nuclear age, arguing that mining uranium and building nuclear plants releases huge amounts of carbon dioxide, and that the danger from accidents or terrorism is too great. In an interview during a stop in Manhattan last week with his wife, Sandy, Dr. Lovelock, still fit and feisty at 87 and seemingly relishing his role as provocateur, said that such objections were baseless and dangerous.

He also offered a daunting prescription for avoiding utter catastrophe, while adding that something just short of that was clearly already under way.

Q. Why do you call it global heating and not global warming?
A. Warming is something that s kind of cozy and comfortable. You think of a nice duvet on a cold winter s day. Heating is something you want to get away from.

Q. What s your perception of where we re headed with even conservative predictions for growth of both populations and energy use?
A. I think we re headed straight back to the Earth s second stable state, which is a hot state that it s been in many times before in the past. It s about 14 degrees warmer than it is in these parts of the world now. It means roughly that most life on the planet will have to move up to the Arctic basin, to the few islands that are still habitable and to oases on the continents. It will be a much-diminished world.

Q. Can you explain why you think nuclear power is so vital?
A. The really bad thing we did way back when was starting to burn things in the atmosphere to get energy. We started with fire, just cooking food, and probably could have gotten away with that. But once we started burning forests to drive the animals out as a cheap way of hunting, then we started on our downward course. What we re doing now with fossil fuels is just as bad. We live in a nuclear-powered universe. We re the oddballs by getting energy from burning carbon. My justification of nuclear power is that we ve reached a stage now where the dire things that threaten us are so great that even the results of an all-out nuclear war pale into insignificance as unimportant compared to what s going to happen.

Q. You seem to say we have to get over the idea that renewable energy sources — wind, solar — in the short run, are a useful way out of this.
A. I feel they re largely gestures. If it makes people feel good to shove up a windmill or put a solar panel on their roof, great, do it. It ll help a little bit, but it s no answer at all to the problem.

Q. What is it about this issue that you think fails to capture adequate public or political attention?
A. I think it s mainly because scientists, and I include myself amongst them, have not really understood what was going on until very, very recently. And also scientists tend to look at things much too academically. What really got me to write the book was going to a meeting at the Hadley Center, a big climate lab near where I live, and talking to all the people there. And Sandy came with me, and we both got the impression that they were talking about the Earth as if it was another planet, not something they were actually standing on. And they re all talking about their own separate little bit. One was talking about glaciers melting, another about tropical forests in trouble. But they didn’t put it together as a whole-planet phenomenon. And when you did that, then each of their gloomy stories together became a devastating thesis.

Q. You say in the book that sustainable development is a fantasy, essentially, and you have a different notion for what needs to happen, of “sustainable retreat.”
A. At six-going-on-eight-billion people, the idea of any further development is almost obscene. We ve got to learn how to retreat from the world that we’re in. Planning a good retreat is always a good measure of generalship.

Q. If you could take any facet of society — elected officials, doctors, writers — and show them one thing that you think could motivate the scale of change you’re talking about, any idea what you might do?
A. I would take them on a trip to the parts of the world where the changes are now maximum, and that is the Arctic. For example, not many years ago explorers were walking with dogsleds all the way to the North Pole regarding it as a great adventure. It s only a matter of perhaps 30 years when they’ll have to go there in a sailboat.

Q. You seem to have two messages at once. One is sort of a hopeful sense of the innovative and adaptable aspect of humans, and the other is that we re going to need all those skills.
A. The human species has been on the planet for a million years now. We ve gone through seven major climatic changes that are equivalent to this. The ice ages were shifts in climate comparable with this one that’s coming. And we ve survived.

That series of glaciations and interglacials put the pressures on us to select the kind of human that could adapt. And we re the progeny of them. And we re just up against a new and different stress. Maybe we ll come out better.

(Por Andrew C. Revkin, The N.Y. Times , 12/09/2006)