The Duke of Cambridge has urged the world to "act now" to tackle the climate crisis "for the sake of future generations".
William issued the stark warning that "our planet is now in crisis" during a five-part series looking at the environmental issues behind his Earthshot Prize.
Each year until 2030, five winners will be awarded £1 million prizes for solutions to the planet’s environmental problems.
In the first episode, which airs on BBC on Sunday, the duke reveals it was US President John F Kennedy’s moon landings that inspired him to launch the prize.
Standing beside water in the Norfolk countryside on a moonlit night, William said: "In reaching for the moon we found the earth. For the first time we could see that the world we live on is finite and precious.
"Ultimately, it woke us to a distressing truth we are still trying to come to terms with – the modern world we have built is at odds with the planet we live on."
Who will win the first £1 million Earthshot Prize money?
The three finalists in each category are featured during the series.
They include a 14-year-old girl from India who has designed a solar-powered ironing cart.
The government of Costa Rica is also up for the prize, having pioneered a project paying local citizens to restore natural ecosystems.
While a Chinese app that allows its citizens to hold polluters to account is also in the running.
The Earthshot Prize winners will be announced on October 17.
William's words are echoed by Sir David Attenborough, one of the Earthshot Prize judges, who narrates some of the programmes and warned mankind risks creating an “extinction event” similar to the demise of the dinosaurs.
Sir David said: "Over the last 50 years, Borneo has lost 30% of its tropical forests.”
He adds: "The reason wild areas across the world are still being destroyed is simple, in today’s world a wild habitat brings less financial income than a cleared one."
Describing the Earthshot Prize as "the most ambitious environmental prize in history," Williams said: "It’s come to this, our planet is now in crisis, its delicately balanced systems are becoming more and more unstable with every passing year. So for the sake of future generations, let’s act now."
The programmes look in-depth at environmental problems across the globe, from the loss of rainforests in Borneo as palm oil estates have increased, to the destruction of the Amazon for cattle pasture and how dams threaten marine wildlife and the fishing livelihoods of people along the Cambodian stretch of the Mekong river.
Solutions to problems are highlighted, including rewilding and projects aimed at reducing land used in farming.