Lynas researched the subject as he wrote his book, The God Species, which challenges the environmental movement’s dismissal of nuclear energy and other technology. By the time he finished the book, the overwhelming evidence on the safety and effectiveness of GM crops had changed his mind.

“It did take me two years to pluck up the courage to write up what I did in the book,” he says. “And what I said in Oxford was even more blunt – and it took me another two years to say that. But I felt pushed by my own conscience.”

Since his January speech, he’s faced intense rebuttals from former colleagues – a reaction that doesn’t surprise him. “This (subject) tends to be something with very little middle ground,” he says. “It’s not possible to change the mind of activists whose stake in the issue is a religious devotion to the natural world.”

Within the movement, the mythology that he calls a naturalistic fallacy is so powerful that what many people believe is opposite of true, he says. It’s the belief that everything natural is good and everything artificial is bad. “For organic, the naturalistic fallacy is elevated into the central guiding principle for an entire movement. This is irrational, and we owe it to the Earth and to our children to do better.”