Science Questions with Surprising Answers
Answers provided by
Dr. Christopher S. Baird

How many years do we have until the earth becomes so over-populated that people won't be allowed to have children?

Category: Society      Published: November 19, 2012

The earth is not in an immediate danger of over-population. This misconception has been around for centuries. Over-population alarmism is driven by various political and environmental ideologies. In 1980, a brief boom in births globally lead some activists to proclaim that if trends continued, calamity would ensue. The only problem with this exercise in extrapolation is that trends did not continue.

Birth rates have been steadily declining. U.S. Census Beareau data shows that the global population growth rate in 1980 was almost 2%. The rate today (2012) is about 1% and steadily dropping. If every family in the world had a house and if every house were stacked end-to-end and front-to-back in one gigantic complex, the entire current world population could be housed in California alone. And this calculation does not include the possibility of building up. If people were to live in 100-story high apartment buildings stacked end-to-end, front-to-back, and top-to-bottom, then the entire world population could be housed in San Diego alone. The problem with over-population disaster scenarios made by alarmists is that they typically extrapolate the population growth but don't extrapolate the advance of technology. The improvement in agricultural efficiency, medicine, and residential construction has out-paced the growth in population. As a result, the world's standard of living has on average improved, despite the population growth. This effect will continue in the future. It's true that there are ever more mouths to feed and cars to fill with gasoline, but there are also ever better ways being developed to make food and extract gasoline. Even if thousands of years hence the earth did begin to approach dangerous levels of population and technological progress stalled, the decline in quality of life would naturally lead to lower birth rates long before the situation ever became cataclysmic. In truth, the earth is far from over-populated, as the population density map below reveals.

world population density map
This world map shows the significantly inhabited regions in red (i.e. places with population density greater than 0.17 persons per acre). Note that aside from India, eastern China, central Europe and a smattering of cities, the world is largely uninhabited. Notably Antarctica, Africa, Australia, South America, Eastern Russia, Scandinavia, central United States, Canada, and the oceans are all predominantly wilderness. Public Domain Image, source: Christopher S. Baird, data source: U.S. Department of Agriculture.

Topics: birth, birth rate, over-population, population