How will we survive when the population hits 10 billion?

By 2050, an estimated 10 billion people will live on earth. How are we going to provide everybody with basic needs while also avoiding the worst impacts of climate change? In a talk packed with wit and wisdom, science journalist Charles C. Mann breaks down the proposed solutions and finds that the answers fall into two camps -- wizards and prophets -- while offering his own take on the best path to survival.