A model predicts that the world's populations will stop growing in 2050

Science Daily: Global population data spanning the years from 1900 to 2010 have enabled a research team from the Autonomous University of Madrid to predict that the number of people on Earth will stabilise around the middle of the century. The results, obtained with a model used by physicists, coincide with the UN's downward forecasts.

According to United Nations' estimates, the world population in 2100 will be within a range between 15.8 billion people according to the highest estimates -high fertility variant- and 6.2 billion according to the lowest -- low fertility variant-, a figure that stands below the current 7 billion.

A mathematical model developed by a team from the Autonomous University of Madrid (UAM) and the CEU-San Pablo University, both from Spain, seems to confirm the lower estimate, in addition to a standstill and even a slight drop in the number of people on Earth by the mid-21st century.

The population prospects between 1950 and 2100 provided by the UN were used to conduct the study, published in the journal 'Simulation'. Mathematical equations which are used in scientific fields, such as condensed matter physics, were then applied to this data.

"This is a model that describes the evolution of a two-level system in which there is a probability of passing from one level to another," as explained by Félix F. Muñoz, UAM researcher and co-author of the project.

The team considered Earth as a closed and finite system where the migration of people within the system has no impact and where the fundamental principle of the conservation of mass -biomass in this case- and energy is fulfilled. "Within this general principle, the variables that limit the upper and lower zone of the system's two levels are the birth and mortality rates," Muñoz pointed out and recalled the change that occurred in the ratio between the two variables throughout the last century...

Population chart by Conscious, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license