The End of Eden

In 1961 Lovelock worked with NASA. The space agency wanted to design a lander to search for life on Mars. That, Lovelock thought, was silly. What if a lander set down in the wrong spot? What if Martian life wasn't bacterial?

Lovelock took a conceptual leap. If Mars bore life, bacteria would be obliged to use oxygen to breathe and to deposit their wastes as methane. Lovelock found that Earth's atmosphere contained massive quantities of oxygen and methane, gases that are the very signature of life. Mars's atmosphere was thick with carbon dioxide, the calling card of a dead planet.

That discovery changed his life. He came to see Earth as a self-regulating biosphere. The sun has warmed by 25 percent since life appeared, so Earth produced more algae and forests to absorb carbon dioxide, ensuring roughly constant temperatures. In 1969, Lovelock lacked only a name for his theory. He took a walk with novelist William Golding.

A big concept needs a big name, Golding said. Call it Gaia.

Gaia proved controversial, and not just because the name made New Age priestesses go weak in the knees. ("Gaia's not 'alive' and I'm afraid I'm not a very good guru," Lovelock notes dryly.) Biologists nearly choked -- they argued that organisms cannot possibly act in concert, as that would imply foresight.

Lovelock recalls being denounced at a conference in Berlin.

The intolerance gave him a pain. Lovelock said that the world's biomass can act without being "conscious." "The neo-Darwinists are just like the very religious," Lovelock says. "They spend all their time defending silly doctrine."

Forty years later, talk of an interconnected planetary system is the lingua franca of Earth science. The queen has handed Lovelock a prize, Oxford has invited him to teach, and his small forest lab had more government contracts than he could handle. (In his lab, the octogenarian scientist follows few safety protocols save the dictates of self-preservation. "I can kill only myself; it's a splendid freedom," he says.)

But friends say he's restless.

"Maybe Jim thinks the world has gotten too comfortable with his theory," says Lee Kump, a prominent geologist at Penn State. "He sees Gaia treating us as a body does an infection -- it's trying to burn us out."

"The meltdown of Greenland's ice sheet is speeding up, satellite measurements show."