Overpopulation A Concern Of The Past? This Study Thinks So.

Overpopulation may not be such a big threat after all: using global population data from 1900 to 2010, scientists have developed a mathematical model showing that the number of Earth's inhabitants may level off in the next 40 years.

Conducted by a team of researchers from the Autonomous University of Madrid and CEU-San Pablo University, the numbers correspond with the lower estimates developed by the United Nations, which fall as high as 15.8 billion by 2100 in the case of high fertility and as low as 6.2 billion given low fertility.

The study, published in the journal Simulation, considered the Earth as a closed and finite system in which migration did not alter the principle of the conservation of mass (in this case people) and energy is fulfilled, according to a press release. Furthermore, it adjusted for the possibility of moving between zones of the two-level system, which is to say researchers took into account the fact that periods of high and low fertility may alternate over the next several decades.

"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," UAM researcher and study co-author Felix F. Muñoz explained.

Describing the past, Muñoz said, "We started with a general situation where both the birth rate and mortality rate were high, with slow growth favoring the former, but the mortality rate fell sharply in the second half of the 20th century as a result of advances in healthcare and increased life expectancy and it seemed that the population would grow a lot. However, the past three decades have also seen a steep drop-off in the number of children being born worldwide."

As an exmaple, Muñoz pointed to a 1992 prediction that a total of 7.17 billion people would inhabit the Earth by 2010. However, when the year actually rolled around, that number was just 6.8 billion. In all, the study states, fertility rates has fallen by more than 40 percent since 1950.