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 was 15 years old when I first heard the name Mandela, or Madiba, as he is fondly known in Africa. In apartheid South Africa he was public enemy number one. Shrouded in secrecy, myth and rumour, the media called him 'The Black Pimpernel'.

There is no definition of terrorism and there is still the reality that one person's terrorist is another person's freedom fighter.

I think even though he [Nelson Mandela] was feted and praised as he was, he always was at pains to say, I'm a human being.

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.

I first met Nelson Mandela when I was in my late 20s, in 1993. I was helping facilitate an African National Congress (ANC) workshop to plan its media strategy. I went down to meet him for the first time and you know me I got stupid... I just choked. I said, "Hello Madiba, it's a real honour to meet you," and I couldn't get another word out.

You know how they say, 'What happens in Vegas, stays in Vegas?' What happens in the Arctic doesn't stay in the Arctic.