As a global community, let’s work towards the United Nations’ lowest population projections, which show global stabilization as soon as the year 2050. This would be good for people, other species and the global ecosystem.
The United Nations estimates that it would cost an additional $3.5 billion per year to provide contraceptive information and services to the more than 220 million women in the developing world who want to avoid a pregnancy but who are not using a modern method of contraception. (That’s less than 4 percent of what Americans spend on beer each year.) That’s a very small price to pay for a more sustainable world. Combine that investment with efforts through entertainment mass media and other means to change attitudes and behavior towards girls and women in the developing world, and we can stabilize world population at 8.3 billion and then begin a gradual reduction in the total number of humans on the planet as soon as 2050. If we can stick to the United Nations’ low variant, by 2100 global population would be back down to 6.7 billion.
The alternatives are not good: in the business-as-usual “medium” scenario, global population will continue rising to almost 11 billion by 2100. The 4 billion person difference between the low projection and the medium is far more than the current combined populations of North America, Central America, South America, Oceania, Europe, Africa and India combined.
(Source: Population Possibilities - UN Population Division)