Australian ecologist Corey Bradshaw and environmental scientist Barry Brook of the Environment Institute of The University of Adelaide, Australia have modeled projected population growths for the world.
Prompted by concerns wildlife, human-made climate change and human overcrowding, both scientists worked together on models of population growth to see if this could be changed. They set up nine models. Currently, it is thought that there are 7.2 billion people alive today and that is expected to rise to 10.9 billion in the year 2100.
Three of the models approached the issue using non-catastrophic methods. The first is that of female empowerment and wide spread use of contraception and the other two were both ‘forced’ one-child policies. While the first policy may be desirable, the latter two raise awkward ethical questions.
The other six models were catastrophic envisioning mass destruction of people by the effects of climate change, conflicts, and pandemic disease. One of these was the World War III scenario, which would have reduced population by 5% and used fatality figures of both combatants and civilians in both World Wars and also included the fatalities from 1919’s Spanish Flu pandemic, which killed more people than the previous four years of combat. One scenario drastically reduced the population to just over a billion people. Presumably, a nuclear war scenario was not used, but food shortages caused by human-made climate change were. The food shortages reduced the population by increasing childhood mortality.
In the end the scientists found that only the most extreme measures (draconian one child policy implemented immediately, irresistible pandemic, global conflict and the like) stopped the projected growth in population, let alone reversed it. It appears that, like the weather, population growth is a brute fact that cannot be easily avoided and humanity will have to prepare for its effects and alleviate those.