Sir David Attenborough's stark warning in new Netflix documentary A Life on Our Planet: "It’s about saving ourselves"

When I met Attenborough earlier in the year he was, understandably perhaps, peeved that his project about what he regards as an existential threat to life on Earth faced being derailed by a passing disease of, as he put it then, “no particular significance”.

When we catch up six months later, he acknowledges the pandemic has caused “and will continue to cause immense suffering”. But he believes that the lessons learnt will help in the even bigger battle against global warming.

Hope, he says, may emerge “from the whole world having experienced a shared threat and found a sense that we are all in it together”. He speaks of “encouraging signs” of an increased trust in science, adding “the time for nationalism is over”.

“There must now be cooperation between nations, and cooperation requires giving up things, as well as gaining them. Internationalism must be our approach. There must be greater equality between what nations take from the natural world. The wealthier nations, such as those in western Europe, have taken a lot and the time, perhaps, has now come to give.”

As one of the two international champions in the climate change struggle, he is determined to remain positive. If humans as a species survive, our descendants may find it strange that, in the 21st century’s Great Climate Crisis, we were saved by an autistic teenager and a great-grandfather with a dicky heart and dodgy knees.

An unlikely pair of superheroes, you might think, to stave off the sixth extinction and stop humanity going the way of the ammonites and the dinosaurs. But then, to subvert the Batman saying, we don’t get the heroes we deserve, we get the heroes we need.

Greta Thunberg may divide opinion, but Attenborough is beyond mortal reproach. Seventy years cuddling up to mountain gorillas and whispering about the wonders of the natural world to television audiences in the tens of millions have turned him into a kind of global secular saint, the most famous naturalist of all time, arguably the most trusted man on Earth, and our chronicler and guide to all that is marvellous and beautiful about the planet on which we live.

So, when Sir David Attenborough says we’re screwed – we’re screwed.

That’s essentially the message of A Life on Our Planet. His life, in this case, which seems to have exactly spanned that brief period in history in which we could experience all the wild beauty of the Earth before we destroyed it.

The film is, he says (several times), his “witness statement”. For we are all on trial, all responsible, all guilty, all – spoiler alert, this comes just at the moment in the film when you’ll be feeling at your most despairing – with a last chance to avert the disaster we have caused.

It’s powerful because the pictures are, of course, breath-taking, the case histories heart-breaking, the argument clear, the solutions simple – some would say too simple. But most of all, it’s powerful because it’s him.

At 94, Attenborough is a bit more lined and crocked in the flesh than he appears on screen, but still somehow boyish in both his looks and his undimmed enthusiasm. The difference is that now he is driven. Gone is the judicious detachment of someone who once ran much of the BBC. He may still be the middle-class Englishman incarnate but, on film, and shuffling into the room with a wary smile, a characteristic squaring of the shoulders and tilting of the head, he is a climate change zealot.

There’s not much time left, he says, for him or the planet: “We’re facing nothing less than the collapse of the living world.” Certainly, there’s no time for understatement or mealy-mouthed qualification.

I ask him if there was a moment when he realised that it wasn’t just the survival of individual species, or even whole ecosystems, that was at stake, but the future of the Earth itself. He remembers it, he says, all too clearly. “I was diving on a coral reef [in 1998, while filming the landmark BBC series, The Blue Planet]. I slipped into the water thinking I would see what I was accustomed to seeing, but instead, I saw a white cemetery of coral that had simply died… That was truly frightening.”

It’s there in the film. Ghostly, shocking, the coral is no longer bursting with life and dazzling colour but bleached into the jagged white tombstones of a dead world. It’s the result, scientists say, of an average rise in sea temperature of just one degree Celsius. As a metaphor for the way we are destroying what Attenborough repeatedly calls “our Garden of Eden”, it is chilling.

A Life on Our Planet is big on metaphors. Attenborough takes as his starting point Chernobyl, prowling around the still-poisoned wreckage of the nuclear power station in Ukraine that exploded in 1986, ironically during a safety test. “The most costly mistake in the history of mankind”, he calls it, which is probably hyperbole but that hardly matters. For it’s a symbol to him of what we are doing to the Earth, “our finely tuned life-support machine”.

“Bad planning and human error – it, too, will lead to what we see here,” he says, sombrely, as he hobbles through the ruins, “a place in which we cannot live”.

And it’s happened in his lifetime. The film shows a young actor playing him in his childhood, ferreting for fossils in a quarry near his home in Leicestershire. It was ammonites he was looking for, molluscs that were once as widespread and successful as humans are now, but were wiped out, along with the dinosaurs, in a sudden “extinction event” 66 million years ago.

Now, Attenborough says, we’re facing another extinction, and it’s entirely down to us; our greed, our thoughtlessness but, most of all, our sheer numbers. When he was fossil hunting in his schoolboy shorts before the war, there were two billion people; now there are nearly eight billion and we could be heading for a peak of nearly 11 billion by around 2100.

“Humans have broken loose,” he says in the film. “Predators have been eliminated, we have food to order, diseases under control [he didn’t foresee coronavirus, needless to say], there is nothing to stop us, unless we stop ourselves.”

It’s a long indictment. In his lifetime, half the world’s rainforests have been razed. The number of Bornean orangutans is down to 104,700, significantly fewer than were around when he first looked for them in 1956 – it’s estimated that more than 100,000 were lost between 1999–2015 alone. Nearly 90 per cent of the large fish in the sea have been “removed”, as he puts it.

In the decades since Attenborough first applied to join the BBC, the pristine world he’s described has been debauched; the wild animal populations have halved. “A blind assault on the planet,” he calls it, popping up to punctuate his “obituary for the Earth” every few minutes to hammer the message home. His voice seems almost to break as he reaches the end: “Human beings have overrun the Earth”. He shakes his head, sorrowfully. “We have completely destroyed that world.”

That’s it then, you might think. Game over. Soon the planet will be a celestial crisp and we’ll only have battery hens for company. But no.

“What do we do?” he asks. Search me, you think from behind the sofa, but Attenborough has the answer. “It’s straightforward. The only way out is to rewild the world.” Exactly how, you wonder. And, seeing how our limitations have just been underlined by an all-too-wild microscopic virus, you’d imagine rewilding the whole world was rather a big ask.

Quite the contrary. “It’s simpler than you might think,” he says to a background of stirring music. “A century from now, our planet can be a wild place again.”

What follows is a call to arms, with carefully chosen examples to foster optimism and illustrate the human potential for change. On population, he picks out Japan, the country with one of the lowest fertility rates, highest life expectancies and oldest populations on Earth – and hardly any immigration, either – to show how our numbers can be controlled. Not Africa, whose population will triple this century; by 2100, one in three humans will be African.

We must lift the world out of poverty, he says, raise the standard of living without increasing our impact on the planet. If it were a matter of will, or even aid money, that would have happened long ago. The really poor of this world live in failed, war-torn or at least disastrously governed states. Not simple.

Phase out fossil fuels, Attenborough says, belching smoke stacks. Morocco gets 40 per cent of its energy from the sun, he says, but it shines there all the time and they’ve got half the Sahara to park their panels – “Renewables never run out.” That may be true, but they’re often not there when you need them, either.

I raise some of these caveats and he brushes them aside. “How many problems do you want to solve at the same time?” he asks, only a touch tetchily. “What would you do? Say ‘Oh well, it’s just too complicated’?” There’s no answer to that, of course.

Food’s the big thing. We must be more like the Netherlands – small place, lots of people but by treating agriculture as a vertical as well as a horizontal business it has become the world’s second largest food exporter. There are astonishing pictures of what look like artificial fields stacked on top of one another.

But that’s not enough. “The planet can’t support billions of meat eaters,” he says. “If we all ate only plants, we’d need only half the land we use at the moment.”

I ask the obvious smart-Alec question: when did he last eat meat? “Can’t remember, years ago,” he says, rather airily. Then, after a long pause: “I eat fish, and chicken, and my conscience does trouble me. I’m affluent enough to afford free range, but it’s a middle-class hypocrisy.”

Attenborough is not a hypocrite. He’s both a national treasure and an old man in a hurry, convinced that if people only knew, they would elect governments that would get together internationally, raise huge amounts of money, agree to protect and expand the wild places, change our lifestyles, limit our numbers…

Does he think he’ll see that in his lifetime? “It’s theoretically possible. It could happen,” he says. But then he adds, sadly: “I don’t think it will.”

It won’t be for the lack of trying. He has more television series on the stocks, conferences to address, governments to lobby. I wonder aloud if he wants to be remembered as a prophet or a programme-maker, and am put straight very firmly. “I don’t waste any time at all thinking about how I will be remembered. It seems to me to be of no possible consequence.”

He ends the film back in Chernobyl, which, 30-plus years on since the disaster, has largely returned to the wild, a symbol for him of hope rather than despair – how nature could reclaim what we have despoiled, how the Earth could recover if only we would let it.

“In the end,” Attenborough says, “it’s not really about saving the planet. It’s about saving ourselves.” And nobody has tried harder than him.

This interview originally appeared in the Radio Times magazine. For the biggest interviews and the best TV listings subscribe to Radio Times now and never miss a copy. If you’re looking for more to watch, check out our TV Guide.