Barack Obama: “Global warming is not a someday problem, it is now.”

And I will fight for that, even if I don’t always think it’s going to win.

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.

If I had a blame pie for why politics is so polarised and why we're seeing a rise of populism in many places, it's because of that information that is going into our brains every day.