A new study concludes that strict fertility measures, such as a one-child policy, or even a mass catastrophe like a global plague or a third world war, would not have a significant effect on the human population trajectory this century.

To reach this rather surprising conclusion, researchers Corey Bradshaw and Barry Brook from the University of Adelaide's Environment Institute analyzed recent UN estimates projecting a global population of 11 billion people by 2100. The work reaffirms a related report suggesting that the world's population is unlikely to stabilize this century, leading to a potential population bomb.

Bradshaw and Brook ran a series of models to see what would happen to population trajectories under a number of stressful conditions. Results showed that even stringent fertility restrictions or mass catastrophic mortality would not bring about large enough change this century to resolve issues of global sustainability.

"We examined various scenarios for global human population change to the year 2100 by adjusting fertility and mortality rates to determine the plausible range of population sizes at the end of this century," noted Bradshaw in a statement. "Even a world-wide one-child policy like China's, implemented over the coming century, or catastrophic mortality events like global conflict or a disease pandemic, would still likely result in 5-10 billion people by 2100."

Incredibly, even a global war wouldn't have a discernible effect.

"We were surprised that a five-year WWIII scenario mimicking the same proportion of people killed in the First and Second World Wars combined, barely registered a blip on the human population trajectory this century," says Brook.

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Specifically, their research, which now appears in the journal PNAS, showed that a mass mortality event of two billion deaths — yes, two billion — over a hypothetical five year window in the mid 21st century would still yield around 8.5 billion people by 2100.

The researchers say this "virtually locked-in" population growth means the world must focus on policies and technologies that reverse rising consumption of natural resources and enhance recycling," adding that "effective family planning and reproduction education worldwide have great potential to constrain the size of the human population and alleviate pressure on resource availability over the longer term."

It could take centuries, say the researchers, for trends in population growth to level off.

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"Our great-great-great-great grandchildren might ultimately benefit from such planning, but people alive today will not," says Brook.

This is obviously a very sobering conclusion, but one that needs to be interpreted as a warning rather than an actual prediction. It's a normative, computer-modeled analysis that doesn't take social trends into account, technological advancements, or political prescriptions. Contrary to the warnings of the neo-Malthusians, this isn't necessarily our destiny.

Read the entire study at PNAS: "Human population reduction is not a quick fix for environmental problems". Supplementary information via University of Adelaide.

Top image: Stokkete/Shutterstock.