Jeffrey Sachs : Earth 's population will hit 7 billion this year ; milestone , huge challenge . Success at reducing high fertility rates depends on keeping girls in school , ensuring that children survive , and providing access to modern family planning and contraceptives . He says with earth 's resources already stretched thin , rapid growth is cause for concern . He asks : How do we increase opportunities for all , leave a usable planet for future ? Others : Vital to switch to sustainable agriculture , cut fertility rates .
Jeffrey Sachs : Earth 's population will hit 7 billion this year ; milestone , huge challenge . He says with earth 's resources already stretched thin , rapid growth is cause for concern . He asks : How do we increase opportunities for all , leave a usable planet for future ? Others : Vital to switch to sustainable agriculture , cut fertility rates .