You know, you only get to live life once, so there are two things that that yields. One is that there's no point in crying over spilt milk, but secondly you hate wasting time, energy, and whatever talent you've got...

The problems that the world faces - from nuclear proliferation to climate change - can't be tackled by the West alone. They need a coalition of not just West and East, but they need a coalition of Christian and Jew and Muslim.

First, climate change is the greatest long-term threat faced by humanity. It could cause more human and financial suffering than the two world wars and the great depression put together. All countries will be affected, but the poorest countries will be hit hardest. Secondly, the costs of inaction far outweigh the costs of action.

Everything about my politics has been about the future.

I think the wonderment of seeing my two sons developing makes me incredibly optimistic about human potential. It makes you think: 'My goodness. It's a miracle that's going on here. What could the human race do together?'

Thirty years ago, if you said the country was living beyond its means, people would have thought about economics. Now, if you talk about the country, or the planet living beyond its means, you think about the environment. We are taking out more than we are giving back. We are consuming energy, water, and other natural resources in a way that is leading to huge and often irreversible damage to the planet. So too are most other developed nations. And so too will China and India if they follow the same path of economic development as us

The biggest opportunity in 2013 is in Africa. It has seven out of the ten fastest-growing economies in the world. In Nigeria alone there are 100 million people with mobile phones. In total, 300 million Africans - five times the population of Britain - are in the middle class.