Author Jostein Gaarder has become more concerned with our environmental future than philosophical questions, he tells Joe Humphreys

For a best-selling author, whose work has been translated into more than 40 languages, Jostein Gaarder is awfully dismissive about books. But then, the Norwegian creator of Sophie's World is no longer first and foremost a writer.

"More and more, I don't read philosophy any more. I don't read fiction. I read natural science," he revealed on a visit to Dublin.

The 53-year-old, who spawned a publishing sensation when his novel, subtitled An Adventure in Philosophy, was translated into English a decade ago, is now perhaps most comfortable with the tag "environmentalist".

Of course, he still writes books. His latest novel, The Orange Girl, has gone global, and he is a planning an anthology of his work for 2006. But he is at his most animated when talking about climate change, and how world opinion on the matter has been "spat on" by the United States.

Gaarder has also put what he calls "a lot" of his income from writing into setting up the philanthropic Sophie Foundation, which awards $100,000 (€83,460) annually to organisations working on nature conservation.

"Today all the books of Plato are translated into Norwegian. That's good," he says. "But at the same time we are making extinct a lot of plants and animals, and they are older than Plato. We have a cultural inheritance. But we also have a biological, or genetic, inheritance. It's very possible that in hundreds of years there will be no life anymore. I am more worried about that than about the lack of translations of Plato's dialogues."

Some may see an irony in Gaarder expressing such views, given the number of trees that must have been pulped for Sophie's World alone. Has he undergone a latter-day conversion, prompted by ageing (he has recently become a grandfather), or perhaps guilt?

He shakes his head. "I will tell you a story," he says. "When I was 25 years old I was always thinking I was ill. I was like a . . . " A hypochondriac? "Yes," he says. "I knew I should die. Where did I find consolation? I went to the woods, and I lay down in the grass and I said, 'OK, I am not only in this nature, I am this nature.' It's a question of identity. I am part of the universe."

To deny this fact is not just unethical, he suggests, but irrational. "If I had two buttons, and if I pressed the first I would die immediately, and if I pressed the second I would live a normal life but all of humanity would die in 200 years, I am convinced I would press the first button. Why? Not because I am a very kind person. I am selfish. But this individual is only part of my identity," he says, patting his chest.

"Maybe this earth, this planet we live on, is the only place in the universe that has consciousness. If so, it's not only a global responsibility to defend life on earth, it's a cosmic responsibility."

That's not to say he sees "nature" as somehow superior to humanity. "I don't agree that we should just pass away and die and the planet will do well without us. I think we are especially precious creatures on this planet. So I am a humanist, not only a pantheist, and not only an environmentalist."

But what of Gaarder the Author? Has he been lost in this cosmic vision? Not quite. Gaarder is still passionate about literature, albeit in a somewhat other-worldly sense. "We don't need books," he says. "But we need stories. I believe we need stories, paying no attention to the content of those stories."

Once again, Gaarder the Conservationist is not far away. He fears our tradition of oral story-telling is in decline - that the invention of the printing press may have only given it a stay of execution. Some societies, he points out, are moving from a "preliterate culture" to a "television culture" without any apparent attempt at recording their narrative heritage.

Moreover, he says, "more and more, the entertainment industry has taken over. We pay so much attention to what happens right now: for instance, 'Who did Pamela Anderson sleep with yesterday?' But these things are so empty of content and stupid."

The uncertain future of story-telling in a "post-modern" world was the theme of a public lecture that Gaarder gave at Trinity College, Dublin on Saturday to mark the centenary of that university's Chair of Education. The author, who received an honorary degree from the college the previous day, expressed his concern about the matter in appropriate fashion: by telling a story.

"I heard the following episode taking place in a small family," he said. "A little girl brings a book to her mother and asks her to read it for her. Her mother, who has got a lot on her plate at the moment, shakes her head and says: 'Not now, dear Ann.' Or: 'Another time, darling.' But the little girl keeps on. 'Please read it to me,' she says, 'you must read it to me!' 'We haven't got time,' her mother sighs. At which her daughter looks up at her with a vexed expressed and exclaims: 'I've got time!' "

The anecdote is classic Gaarder, not just because of its narrative form but because of the protagonists: on the one hand, a wide-eyed child filled with wonder, and, on the other, a "practical", or unquestioning, adult. Such protagonists feature strongly in his work, including Sophie's World, reflecting his own experience of alienation as a child when, he says, "I asked my teachers, 'Don't you think it's weird that we live in this world?' And they replied, 'Jostein, you shouldn't go around thinking these things.' My book were kind of a revenge against that."

As for "that book", he says he was initially "baffled" by its success. The novel, which wraps an introduction to Western philosophic thought around the story of a curious 14-year-old Scandinavian girl, has more than 20 million copies in print. How come? Gaarder replies: "My experience from travelling all over the world is that human beings are human beings are human beings. I was in a classroom in Tokyo and I asked the young students there, 'What are the most profound human questions?', and they gave me exactly the same questions I would have got from students in Norway."

People may be asking the same questions but are they giving the same answers? On the environment at any rate, the answer is no, as Gaarder confirms.

He says he is frequently asked, "What are the most basic values?" And in reply he lists four things: first, health; second, friendship (he says, "a terrible problem in society today are people being lonely"), third, "erotic friendship"; and fourth, "unspoilt nature, wilderness".

"I say this all over the world, and they reply: 'Oui, oui'; 'Ya, ya'; 'You are so right, you know'. And then I come to the fourth thing, and they reply in Tokyo, in Sao Paulo, in London, in Paris, "Really? No! Is that a basic value?"

For information on the Sophie Foundation see www.sophieprize.org