Population Growth Is Unstoppable, Researchers Claim

October 28, 2014 Posted by Editor

There are few philosophical currents which resisted and even consolidated over time better than Malthusianism. More than two centuries after the British political economist wrote his famous thesis, scientists, journalists and social commentators use the ‘population growth’ argument when demographers release new sets of data.

The world population past the 7 billion threshold and the UN estimated that by 2050, the planet will hold almost 10 billion humans. However, fertility rates will most likely curb during the next decades. Nevertheless, people have consumed resources and will continue to do so, there’s no argument about that.

Corey Bradshaw, professor at University of Adelaide in Australia and Barry Brook from University of Tasmania decided to offer an answer to the troubling question: how will the world population evolve in the next decades? The team ran nine models and they all produced more or less the same result: population growth is unstoppable.

“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, are still likely to result in 5-10 billion people by 2100,” said Corey Bradshaw,.

Even when they introduced the effects of catastrophic events in the models, the results have been similar.

“We were surprised that a five-year WW III 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,” said Barry Brook from University of Tasmania.

First, placing the climate change question under a Malthusianist cover, as many have done, raises a series of ethical, as well as political questions, simply because rich countries have produced the highest levels of pollution.

A closer look at the data on living conditions in the last decades clearly shows that when people enjoy better living standards, they have fewer children. However, the main argument behind the population growth drama stands on culturalist foundations (see the appeals to vice and misery).

But empirical data proves that behavior, including reproductive one, can be adequately explained through social factors. Put it differently, poverty increases the number of children in a family, not the other way around. If poverty is one major explanatory factor behind population growth, then proper redistribution of resources would be an adequate measure to increase the quality of life of the existing population. As data from countries with lower economic inequality level shows, population growth tends to stabilize.

Cog

ZPG. Old stink, new face.
Rudy Haugeneder

INCREDIBLY FRIGHTENING . . .

. . .

Human population reduction is not a quick fix for environmental problems says the title.

Corey J. A. Bradshaw1 and Barry W. Brook

Author Affiliations

Edited by Paul R. Ehrlich, Stanford University, Stanford, CA, and approved September 15, 2014 (received for review June 5, 2014)

Significance

The planet’s large, growing, and overconsuming human population, especially the increasing affluent component, is rapidly eroding many of the Earth’s natural ecosystems. However, society’s only real policy lever to reduce the human population humanely is to encourage lower per capita fertility. How long might fertility reduction take to make a meaningful impact? We examined various scenarios for global human population change to the year 2100 by adjusting fertility and mortality rates (both chronic and short-term interventions) to determine the plausible range of outcomes. Even one-child policies imposed worldwide and catastrophic mortality events would still likely result in 5–10 billion people by 2100. Because of this demographic momentum, there are no easy ways to change the broad trends of human population size this century.

Abstract

The inexorable demographic momentum of the global human population is rapidly eroding Earth’s life-support system. There are consequently more frequent calls to address environmental problems by advocating further reductions in human fertility. To examine how quickly this could lead to a smaller human population, we used scenario-based matrix modeling to project the global population to the year 2100. Assuming a continuation of current trends in mortality reduction, even a rapid transition to a worldwide one-child policy leads to a population similar to today’s by 2100. Even a catastrophic mass mortality event of 2 billion deaths over a hypothetical 5-y window in the mid-21st century would still yield around 8.5 billion people by 2100. In the absence of catastrophe or large fertility reductions (to fewer than two children per female worldwide), the greatest threats to ecosystems—as measured by regional projections within the 35 global Biodiversity Hotspots—indicate that Africa and South Asia will experience the greatest human pressures on future ecosystems. Humanity’s large demographic momentum means that there are no easy policy levers to change the size of the human population substantially over coming decades, short of extreme and rapid reductions in female fertility; it will take centuries, and the long-term target remains unclear. However, some reduction could be achieved by midcentury and lead to hundreds of millions fewer people to feed. More immediate results for sustainability would emerge from policies and technologies that reverse rising consumption of natural resources.

demography fertility catastrophe war mortality

Footnotes

1To whom correspondence should be addressed. Email: corey.bradshaw@adelaide.edu.au.

Author contributions: C.J.A.B. and B.W.B. designed research; C.J.A.B. and B.W.B. performed research; B.W.B. contributed new reagents/analytic tools; C.J.A.B. analyzed data; and C.J.A.B. and B.W.B. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

Data deposition: Data available from the Aekos Data Portal, http://www.aekos.org.au (dx.doi.org/10.4227/05/53869A9434A46).

This article contains supporting information online at http://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1410465111/-/DCSupplemental.
Glen McMillian

Malthus has always been getting the last laugh at one spot or another on the globe and will continue to do so.

A famine or war or pandemic disease is not apt to do much to stop world wide population growth. The research is right on that point.

But such disasters are surely going to result in putting the skids under LOCAL population growth in many places in the future as just as they have in the past.

We talk about the world as if it were one community and one place and of course it is just one big community and one big place in reality from many perspectives.

But population and over population are problems mostly on a regional and national level rather than a world level. Tens of Millions of subsistence farmers don’t have much impact on the environment and if half of them starve as the result of a few bad years which has happened many times in the past and will happen again the world will hardly even notice it happening.

The problem is that countries that are just now modernizing still have high birth rates. Countries from Russia to Japan to Italy to the US have birth rates low enough for their populations to stabilize and eventually to start falling.

My gut feeling is that natural disasters of the flood and drought sort plus pandemic disease will basically solve the population problem for us within the next half century in countries with high birth rates.

It is not pc to mention it but the world is very much a Darwinian place.