Nelson's Mandela own sense of himself was a very humble reading, [different] from how the world read him. And, quite often, you had the sense that he was not comfortable with all the accolades that would be.

One of the things that I noticed with my own eyes was Nelson Mandela ability to engage with kings and queens and heads of state on the one hand, and his ability to engage with ordinary people, equally comfortably.

The reality is today most of our political leaders want to be treated as gods and semi-gods, from the security details to the fuss around them and so on.

My final advice for young people is to not wait for leadership from adult politicians. Step forward today, because our current leaders are denying the dire reality we are facing. Leadership can come form anywhere.

The struggle to avert catastrophic climate change is bigger than all the other struggles, whether it is slavery, democracy struggles, the woman's right to vote, and so on I would argue that if what is at stake is securing life as we know it, then there can be no bigger struggle that we face.

I've come across a lot of people in my life who talk about poverty and talk about the poor, but you rarely have a sense that it matters to them to the point at which they will be willing to sacrifice something.

This week we saw progressive business and faith leaders making strong commitments that are moving ahead of what world leaders promised today. The leaders of major economies must be bolder than they were today in providing a vision for 100% renewable energy for all.