Have less people? So that means what - poor people can't have kids? Lots of people starve? Yes, not exactly practical.
Hopefully the population will start to decline due to lower birth rates... I hope at least. :)
Not that I'm advocating this. I think people should be responsible enough to choose how much to reproduce.
Thats only an option if you have enough money not to have to have enough children to support you in your old age. In much of the world, large families ensure the well-being of parents into old-age. You should be so lucky as to marry, have a ton of kids, mostly males, have them all live. Social security bling bling! This is why poverty and high rates of reproduction go together.