Barack Obama: “The initial transactions are generating a more than 50-precent increase in fuel economy.”

It is a decision about how do we face and embrace this finite amount of time we have on the planet.

People need to “rediscover what’s the story we tell about how we’re going to live together, and see each other, and recognise each other, and disagree, and yet, still care for each other”.

When we choose, when we make that decision, I do believe – and there is evidence for this – that the world gets incrementally better, and that is a worthy goal and it’s worth fighting for.

I think when we act on that basis, it doesn't always work out, but over time things do get better.