Nature isn't positive in that way. It doesn't aim itself at you. It's not being unkind to you.

It seems to me that the natural world is the greatest source of excitement; the greatest source of visual beauty; the greatest source of intellectual interest. It is the greatest source of so much in life that makes life worth living.

You can cry about death and very properly so, your own as well as anybody else's. But it's inevitable, so you'd better grapple with it and cope and be aware that not only is it inevitable, but it has always been inevitable, if you see what I mean.

The whole of science, and one is tempted to think the whole of the life of any thinking man, is trying to come to terms with the relationship between yourself and the natural world. Why are you here, and how do you fit in, and what's it all about.

An understanding of the natural world and what's in it is a source of not only a great curiosity but great fulfillment.

We are not overpopulated in an absolute sense; we've got the technology for 10 billion, probably 15 billion people, to live on this planet and live good lives. What we haven't done is developed our technology.

Dealing with global warming doesn't mean we have all got to suddenly stop breathing. Dealing with global warming means that we have to stop waste, and if you travel for no reason whatsoever, that is a waste.

I think a major element of jetlag is psychological. Nobody ever tells me what time it is at home.

Before the BBC, I joined the Navy in order to travel.

I like animals. I like natural history. The travel bit is not the important bit. The travel bit is what you have to do in order to go and look at animals.

Many individuals are doing what they can. But real success can only come if there is a change in our societies and in our economics and in our politics.

All we can hope for is that the thing is going to slowly and imperceptibly shift. All I can say is that 50 years ago there were no such thing as environmental policies.

It's coming home to roost over the next 50 years or so. It's not just climate change; it's sheer space, places to grow food for this enormous horde. Either we limit our population growth or the natural world will do it for us, and the natural world is doing it for us right now.

All our environmental problems become easier to solve with fewer people and harder - and ultimately impossible to solve - with ever more people.