The CBC "Offbeat Math" page has some interesting ways to interpret how many people that is. One that struck me is that if we were ALL at a concert - standing room only - we'd take up half of PEI. That doesn't seem like that much to me. But if we all stood hand-in-hand, we'd form a chain 7 million km long, nine times the distance to the moon.
Finally, the web page has a video interview with Joel Cohen, a math biologist from Columbia University. He makes it clear that we are prospering on borrowed time. One of the interviewers says that growing world population is a boon to the stock markets, and a dream scenario for investment in general (I can only assume that he's playing devil's advocate, and asking what other people might be wondering). Prof. Cohen repeats his stance, that this rate of growth cannot continue and current prosperity is at the expense of future generations.