How many people is too many for earth? At our current rate our population is doubling roughly every 50 years. It's estimated that by 2054 our population will reach 12 billion. Since the dawn of agriculture (8000 ad) our population has increased rapidly. From 8000 ad to 1 ad the population changed from 5 million to 200 million. The industrial revolution helped us reach our first billion in 1804. The second billion was reached in only 130 years (1927). The third billion only took 33 years(1960). The 4th billion only took 15 years(1975). The 5th billion only took 12 years(1987). The 6th billion only took 12 years(1999). The 7th billion only took 12 years(2011). Not only does an increase in population require more housing but it also requires more room for creating food, more room for landfills, more stores, more everything. How many people can our world realistically support and for how long before we run out of resources? Will the space program ever be opened back up to look for other planets for resources or to live? Btw got most of the info off world population clock. Also the Daniel Quinn has some good books that bring up some really good points on this subject.