Fundamentally not to waste energy. If we were all to reduce our demands for energy, it would make an enormous amount of difference.

You can only get really unpopular decisions through if the electorate is convinced of the value of the environment. That's what natural history programmes should be for.

I suppose happiness is something one enjoys, but I suspect that happiness is not a state but rather a transition.

Well, I'm having a good time. Which makes me feel guilty too. How very English.

We can now manipulate images to such an extrodinary extent that there's no lie you cannot tell.

I'm no longer sceptical. I no longer have any doubt at all. I think climate change is the major challenge facing the world.

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.