Overpopulation, conceptual image. Artwork of a crowd of human couples representing overpopulation of the Earth. The Earth's population grew rapidly in the 20th century due to increased healthcare, reduced infant mortality and increased life expectancy. In the early 21st century, the world population is over 6 billion, and it is thought the global population could reach 11 billion by 2050. There are concerns that the human population may exceed the available resources.