A few years ago I had the opportunity to hear the CEO of an agricultural biotech company speak about his proud partnership with no-love-of-humanity agri giants Monsanto and Syngenta. As he hoisted his ample gut over his belt, he started to play his imaginary violin about all the hungry people in the world, and how Monsanto & Co were going to help to save the situation by increasing crop yields blah blah blah. He's lucky I didn't have a frying pan handy to doink him over the head with. (I know for a fact this man ate meat at least once a day).
The problem is not lack of food, because if it was, there would be hungry people with money in the world. Almost every hungry person in the world has a lack of funds - which means it is an issue of poverty and a bad system, not a question of yield. Mark Bittman wrote a fantastic article in the NY Times which breaks it down in a very clear way (see below).
Next time someone tells you that our beautiful planet does not have the capacity to grow enough food to feed us, tell them they're wrong. And that they can start to make a difference by having beans instead of meat a few times a week (their health will thank them too :-)).