I gave a speech at the Democratic National Convention in 2016 and warned of Trump. America has survived for almost 250 years with its imperfect democracy, but, you know, maybe it's a better democracy than elsewhere. And I am sure American democracy will survive.

Donald Trump says he wants to run America like he's running his business? God help us.

Fifty percent of the world's population lives in cities. In a couple of decades, 70 percent of the world's population will be living in cities. Cities are where the problem is. Cities are where the solution is, where creativity exists to address the challenges and where they have most impact. This is why, in 2005, the C40 was founded, an organization of cities that address climate change. It started with 18 cities; now it's 91. Cities simply are the key to saving the planet.

When I came into office, people said, 'Billionaire? How do they live? What do they eat? How do they sleep?' Today, they see me on the subway coming uptown. A couple of people say hi, some people smile and nod. Some people just sleep. It's not an issue.

When you go to Washington now, you can feel a sense of fear in the air - the fear to do anything, or say anything, that might affect the polls, or give the other side an advantage, or offend a special interest.

The governor of Texas was a real climate change, well, "skeptic" would be a nice way of phrasing it. Still, though, Texas is a leader in renewables. So, what I care about is what politicians are actually doing, not what they are saying.

I'd love to have a president who really was out there leading and traveling around the world campaigning for joint climate change action. Even the Chinese government is trying to get people to stop polluting. And I think the federal government level in China is acting more responsibly than the American government.