David Attenborough has delivered a heartfelt message to children around the world on how they can help save the planet: “Live the way you want to live but just don’t waste.”

At the first screening of the BBC’s forthcoming blockbuster nature series, Seven Worlds, One Planet, the 93-year-old offered his advice to a five-year-old in the London audience. The boy was overwhelmed by nerves when handed the microphone, so his father asked his question on his behalf: “What can he do to save the planet?”

“You can do more and more and more the longer you live, but the best motto to think about is not waste things,” Attenborough replied. “Don’t waste electricity, don’t waste paper, don’t waste food. Live the way you want to live but just don’t waste. Look after the natural world, and the animals in it, and the plants in it too. This is their planet as well as ours. Don’t waste them.”

A rapt audience of children in India and South Africa joined the event by videolink and lined up to ask Attenborough questions and wave posters. At Mumbai’s packed Royal Opera House, placards read “Sir David please come to India please” and “Sir David can I please come on a shoot with you?”

One asked Attenborough which animal he had found most difficult to document during his 70-year career. “I nominate going to look for mountain gorillas for the first time,” he said. “That was an unforgettable time and more successful than we could possibly have hoped … but it was a long time ago.”

David Attenborough with mountain gorillas in Life on Earth from 1978. Photograph: PA

Asked what was the greatest treat in store for viewers in the new series, Attenborough said: “There’s a wonderful creature called the golden-haired blue-faced snub-nosed snow monkey. I’d never seen film of it before. I once read a scientific paper and thought: we must go and film that! But that was back in the 60s and we couldn’t get to China so in the end I dropped it … and then, blow me, this lot pop up and say ‘we’ve got it’.”

Jonny Keeling, the series’ executive producer, described his excitement at showing Attenborough never-before-seen footage of the monkey, only for him to nonchalantly reply: “Ah yes, Rhinopithecus roxellana!”

‘Ah yes, Rhinopithecus roxellana!’: golden snub-nosed monkeys in Seven Worlds, One Planet. Photograph: Nick Green/BBC Studios

Seven Worlds, One Planet took four years to make, with seven hours of television edited down from 2,000 hours of footage shot on every continent – including drone footage inside a volcano. Keeling said it stood out from other blockbuster nature documentaries because it embedded conservation throughout every episode rather than “just [having] a line about it”.

Tony Hall, the director general of the BBC, said: “There has never been a more important time to bring natural wonders to everybody.” He confirmed the BBC’s commitment to air a landmark nature series every year until 2023. “No other broadcaster comes close to that kind of commitment to the natural world.”

The BBC’s Natural History Unit has faced criticism for what some see as a reticence in spelling out how humans are damaging the natural world. This year, Attenborough’s move to Netflix for Our Planet – which made its message explicit throughout – was hailed as his first act as an “in-yer-face eco-warrior” and many felt it stole the BBC’s thunder.

Attenborough rejects such criticism, saying both he and the broadcaster had long been conscious of the climate crisis. “I don’t think I’ve made a series in the last 40 years where I haven’t made at the end an appeal about caring for the natural world,” he said.

“At the time I daresay people thought we were cranks, but as it’s gone on and we’ve repeated it on and on and on – not wasting things, not polluting things, and so on. Suddenly, for no reason I can understand because the message has been the same, you hit the right note.”

It was with Blue Planet II, he said, that the world became “electrified” about the crime of dumping plastic into the ocean. “Quite what it is that makes the messages ring the bell is very difficult to say. I daresay if we knew how to do it, we would do it more frequently.”

• Seven Worlds, One Planet starts on BBC One on Sunday 27 October at 6.15pm.