David Attenborough turns 95 in May, and he’s the first to admit he hasn’t much time left.

He will leave the natural world in worse shape than when he first touched on it in his groundbreaking natural history series Life on Earth, all those years ago, in 1979. He was solemn, subdued and philosophical in a poignant 60 Minutes profile late last fall, on the eve of his personal witness statement A Life on Our Planet for Netflix.

“Even the biggest and most awful things that humanity has done pale into insignificance when you think of what could be around the corner,” he said quietly. “There could be whole areas of the world where people can no longer live.”

Attenborough witnessed the changes with his own eyes during his research for Our Planet. He visited many of the same wild spaces he first visited for Life on Earth for BBC’s Natural History Unit, more than 40 years ago now.

“Coral reef is one of the most dramatic, beautiful and complex manifestations of life you can find anywhere.

“But during my last trip it was like a cemetery — all the coral reef had died. Because of the rising temperature and acidity.

“We live in a finite world. We depend on the natural world for every mouthful of food that we eat and every lung-full of air that we breathe.

“If it wasn’t for the natural world the would be depleted of oxygen tomorrow. If there were no trees, we would suffocate.”

The Covid-19 pandemic has proved to be a mixed blessing.

“People who have never listened to a bird’s song are suddenly thrilled, excited and inspired by the natural world. They realize they are a part of it. By saving nature, we are saving ourselves.”

There are moments, during those quiet times when he’s on his own and thinks back on his half-a-century’s worth of natural history programming, when he wonders if he had any effect.

“My generation is no great example for understanding. We have done terrible things.”

There is a glimmer of hope, though, he said, and it has come from an unlikely source: The younger generation, as represented by an 18-year-old from Sweden. The 94-year-old and the 18-year-old have become united in a common cause.

What Greta Thunberg has achieved in her short life on planet Earth has been remarkable, he told BBC’s Radio 4 last fall.

What she has done, he said, is “astonishing, and admirable.

“She has achieved things that many of us who have been working on it for 20-odd years have failed to achieve.”

Thunberg, guest host that week of BBC Radio’s Today program, insisted that wasn’t entirely true.

“I’m just a part of a very large group of people who have done it,” she said, in her clipped, accented English.

“And you are a part of that group, too,” she told Attenborough.