The carrying capacity of the Earth is finite, though at which point is unclear. Certainly, contemporary anthropogenic activities are unsustainable. Human impact on the Earth depends on the number of people and per capita resource use. Hence, rapid global population growth, particularly in many lower-income countries, may be the major threat to the Earth's carrying capacity. UN's medium projection is for world population to grow by a billion people per decade, reaching 6,400 billion by the year 2000. The trajectory of population growth in the 21st century will influence patterns of poverty, the transition to a biologically sustainable economy, and the possibility of large scale irreversible degradation of the natural environment.
There are many who believe it is already too late to turn the curve (of total population over time) down gently and that the drop will be catastrophically precipitous. In spite of the frightening shape of the curves, our economic and political leaders all act as if the line going straight up is completely normal -- indeed, desirable and necessary -- even when it is obvious that the explosive growth is without precedent and unsustainable. Every political and business decision seems to be based on the assumption that bringing the curve down is simply unacceptable, but the alternative is a nature-imposed drop that will be all the greater.
The subject of fertility control mainly concerns religious leaders. Throughout history, anthropological, cultural, social and religious norms have supported fertility control. That has been used to subjugate women. Disagreement, then, is not centred so much on the need for population stabilization but on family planning and whether it should occur at the individual level or the institutional level.