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.

People vote against their own interests that all the time. But when you do the polling in the U.S., it has gone from less than 50 percent who thought climate change was real to 70-odd percent. And if you listen to the Republicans in Congress, they used to say, "Oh, climate change doesn't exist." Then they switched to "Well, it exists, but it's not man-made," to "Well, I'm going to address the issue." Why? Because when they go home, the local constituent says, "Wait a second. What are you talking about? We just had a flood. We haven't had rain in a long time." They can't get away from it.

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.

The next day after I got fired, literally the next day, I started a new company.

If it wasn't for O'Flanagan's Pub on Manhattan's Upper East Side, I don't know where I would have spent my Friday nights as a young man.

There are lots of threats to you in the world. There's the threat of a heart attack for genetic reasons. You can't sit there and worry about everything. Get a life.

We will rebuild, renew and remain the capital of the free world.