I find myself increasingly annoyed and sarcastic with people who go on and on about the idea that the world will simply be unable to feed itself in the future, and more specifically by the time we reach 7bn. Luckily for me, the excellent Tim Hartford is less sarcastic and more eloquent and has written an excellent rebuttal of the notion here. Go and read it if you've ever believed the Malthusians who keep telling you that we're doomed without population control. And even if you haven't - it's a great piece.
In case anyone is still confused, the problem is with the logic. People look around and see that we have millions of people who don't have enough food. They assume there must not be enough food. Then they hear that the number of people on the planet is growing. Their conclusion is that more people will result in more hunger, death, war and other bad things. But the fact that people are hungry doesn't necessarily mean that enough food doesn't exists. In fact, there probably is enough food in the world. The problem is not one of food existing (food production), it's one of food distribution. The food exists but people can't get it. It's the difference between everyone being poor and some people being poor while other people are rich.
Producing more food won't solve world hunger*. Producing more food in places where there isn't enough and making it available to the people who can't get at it, might.
*unless for some reason so much was produced that food prices collapsed, which would be bad in the long-term because of economics, etc. and is extremely unlike to happen.