Population Control

At the current population growth rates, by the year 2500 people will be standing shoulder to shoulder on every piece of habitable land on this planet. So while our immediate problems have to do with global warming and obvious aggressions in various parts of the world, at some point population is going to become a focus as well.

It seems somewhat obvious to me that at some point there needs to be a type of population control on this planet. I've been racking my brain trying to figure out how to implement something like that that doesn't have any massive moral implications, and truthfully, I haven't come up with an answer yet. Some people argue that natural disasters and diseases may ultimately solve the population problems for us. That may be true, but I certainly don't think it's representative of the growth this planet has seen. For example, of all the people who have ever lived, laughed and loved on this planet, half of them are alive right now around 6% - 10% are alive right now.

So this is an open ended discussion. Do you think population control is necessary? If so, how would you enact it? Would you tax couples with more than two kids? How does that affect religious groups that refrain from using birth control? What do you think?