Human population: the next half century.

By 2050, the human population will probably be larger by 2 to 4 billion people, more slowly growing (declining in the more developed regions), more urban, especially in less developed regions, and older than in the 20th century. Two major demographic uncertainties in the next 50 years concern international migration and the structure of families. Economies, nonhuman environments, and cultures (including values, religions, and politics) strongly influence demographic changes. Hence, human choices, individual and collective, will have demographic effects, intentional or otherwise.