Now comes the threat of climate crisis - a threat that is real, rising, imminent, and universal. Once again, it is the 11th hour. The penalties for ignoring this challenge are immense and growing, and at some near point would be unsustainable and unrecoverable. For now we still have the power to choose our fate, and the remaining question is only this: Have we the will to act vigorously and in time, or will we remain imprisoned by a dangerous illusion?

When you talk about President Trump, the cable networks turned over so many hours of prime time to him. Why? Because he was entertaining, but also because it drove ratings. And that is different from what the news media is supposed to focus on.

That we can be e pluribus Unum - out of one, many

In physics there's the old law for every action there's a equal amount of reaction. Sometimes that's true in politics. If somebody's out there making nonsensical statements, but wielding power behind them a lot of people say, "Well, I need to react to that." Another reason for the increased prominence of the climate-change issue is the Paris Agreement itself. It's not a small thing when just about every nation in the entire world comes together and makes an historic agreement like this. It's a big deal. And the old cliché "The train is leaving the station" kind of applies.

Anyone who deals with the climate crisis has an internal dialogue between hope and despair, because the challenge is so huge and the danger is so great and the stakes are so high. But I have always resolved that in favour of hope, and actually I'm more hopeful now than I was a decade ago when the solutions were visible on the horizon, but you had to seek reassurance that the technology experts that they're coming, they'll be here.

The presidency is more than a popularity contest.

I saw the logarithmic growth of computer power.