Sir David Attenborough has told Prince William that people have never been more "out of touch" with the natural world than they are today.
In an interview with the prince at the World Economic Forum, the naturalist warned: "We can wreck it with ease, we can wreck it without even noticing."
Sir David said people must care, respect and revere the natural world.
Heeding his words, the prince said: "Work to save the planet is probably going to largely happen on our watch".
Sir David, 92, said: "When I started 60 years ago in the mid-50s, to be truthful, I don't think there was anybody who thought that there was a danger that we might annihilate part of the natural world."
In his early career, he said, simply showing people a new animal on television would astound them.
Even then, he added: "Television in Britain in the 50s was only seen by a few million people in southern England."
Speaking in Davos, Switzerland, the Blue Planet and Dynasties narrator said: "Now we can go everywhere, we can go into the bottom of the sea, we can go into space, we can use drones, we can use helicopters, we can use macroworlds, we can speed things up, we can slow things down, we can film in the darkness - and so the natural world has never been exposed to this degree before."
His new series, Our Planet, due to air on Netflix, could reach 150 million people immediately, he said, "and go on being seen - by word of mouth".
Despite this, he said, with more people than ever living in towns, "the paradox (is) that there has never been a time when more people are out of touch with the natural world than there's now".
He warned: "It's not just a question of beauty or interest or wonder, it's the essential ingredient, essential part of human life is a healthy planet.
"We are in the danger of wrecking that".
He said that for a very long time people have viewed the natural world in opposition to the urban world.
"It is not, we are all one world," he said, adding that global leaders are beginning to see that everything we do has implications.
He said: "That fundamental, beautiful fact is now being recognised."
In his interview with the Duke of Cambridge, Sir David said it was "difficult to overstate" the climate change crisis.
He added: "We are now so numerous, so powerful, so all pervasive, the mechanisms we have for destruction are so wholesale and so frightening that we can exterminate whole ecosystems without even noticing it.
"We have now to be really aware of the dangers that we are doing.
"And we already know that of course the plastics problem in the seas is wreaking appalling damage on marine life - the extent of which we don't yet fully know."
Last year, Sir David said he was "astonished" by the response to Blue Planet II, which raised the issue of single-use plastics and the damage they were doing to the world's oceans.
Sir David was given a Crystal Award at the forum on Monday for his leadership in environmental stewardship.
Accepting the award, the veteran broadcaster urged leaders to come up with "practical solutions".
He told the prince: "The point is that we have this option ahead of us - we have to take the option to protect the natural world… that's where the future lies.
"There's a source of great optimism there, we have the knowledge, we have the power, to live in harmony with that natural world".
Prince William has previously described Sir David as having "the single most important impact in my conservation thinking".
Introducing Sir David, he said it was a "personal treat" to interview the broadcaster.
In a BBC tribute programme marking Sir David's 90th birthday in 2016, the duke called him a "national treasure".
He added: "I used to love, and I still do, but when I was a young boy, used to love turning on the television and watching David's programmes and really feeling like I was back out in Africa or I was learning about something magical and almost out of this planet."
The duke said: "There is something very reassuring about seeing David Attenborough on BBC One doing his documentaries. It is part of the national psyche now."
Sir David turned 90 in the same year as the Queen, and paid his own tribute at her official birthday celebrations at St Paul's Cathedral.
They also took part in an ITV documentary last year which looked at the Queen's Commonwealth Canopy project.
Sir David and the Queen, who were born just weeks apart, chuckled over a forlorn-looking tree in the Buckingham Palace grounds which the Queen suggested had been "sat on" at a garden party.
When Sir David suggested climate change might lead to "all kinds of different trees growing here in another 50 years", the Queen quipped: "It might easily be, yes. I won't be here though."
Prince William, who is patron of the Tusk conservation charity, has in the past warned over the impact of the ivory trade and wildlife trafficking.
In 2016, he urged the UK government to push ahead with a total ban on the ivory trade in a bid to protect elephants.
He also voiced concerns that the African elephant may have disappeared from the wild by the time his daughter Princess Charlotte is 25.