Welcome to Hard Talk on the BBC World Service with me, Stephen Sacker.

James Lovelock, one of the past century's most influential thinkers on environmentalism and natural science,

died last week at the age of 103.

Over the span of his long life, Lovelock didn't describe himself as a scientist. He always preferred to be described as an engineer or inventor.

And that reflected his desire to focus on practical real-world problems and how to solve them with unconventional thinking.

He'll always be best remembered for one big idea,

his Gaia hypothesis, which back in the 1970s had a radical impact on environmentalism. He encouraged

us to see planet Earth, Gaia, as an integrated self-regulating system with the fate of all forms of life

and the planet itself connected and intertwined. From that idea, Lovelock developed a host of strong,

often provocative opinions on what humans should do to best maintain Gaia's balance.

In 2021, I visited him at his home by the sea in southern England to talk about those

provocative ideas and his concerns about the future of humanity and our planet.

This is another chance to hear that interview.

James Lovelock, welcome to Hard Talk. Thank you. Yes, glad to be back. It is such a pleasure

to have you back on the program. I want to ask you for your reflections on your own famous

Gaia hypothesis, that idea that all of life on this planet and

the planet itself are part of one self-regulating system. When you developed the idea five decades

ago, you seemed quite optimistic that this system was very durable, very resilient.

Well, it has lasted three billion years. That's not bad going.

But are you now worried about its vulnerability?

Yes, I am. You see, I see Guy at the system of the earth as about so age as me, in effect. I don't mean it's 102 coming up.

What I mean is it's equivalent to that in the planet's terms. Its time is approaching.

...