San Antonio College Library

Past attempts to answer this question have ranged widelyfrom less than 1 billion to more than 1,000 billion - one sign that there is no single right answer. More than half of the estimates, however, fall within a much narrower range: between 4 billion and 16 billion. In any case, with the world population now at 5.7 billion, and increasing by approximately 90 million per year, we have clearly entered a zone where limits on the human carrying capacity...