The climate activist answers questions from famous supporters and Observer readers, with an introduction by Ali Smith Greta Thunberg. This time last year she was unimaginable. Then, pretty much from nowhere, there she was: small and slight, a girl just turned 16, the way-too-young odd person out on a panel of adults sitting in front of the world’s economic powers at Davos last January. Unshowy and serious, careful, firm, she said it . Our house is on fire. The ancient Greeks had a word for this: parrhesiastes. It means a person who speaks truth to power: you should not be behaving in this way. Don’t. More specifically it suggests someone in whom directness of expression and access to truth coincide; and it means someone of very little power who’s risking everything – because they can’t not, there’s no option – to speak ethical truth to powers so entrenched that they’re close to tyrannical, because telling this truth is about moral law. “Some people, some companies, some decision-makers in particular know