Why does overpopulation matter

While better health care and medicine along with advances in food production and access to freshwater and sanitation have allowed us to feed ourselves and stave off many health ills, some so-called Neo-Malthusians believe we may still be heading for some kind of population crash, perhaps triggered or exacerbated by environmental factors related to climate change. Of course, the immigration that continues to fuel population numbers in developed countries is coming from somewhere. Also fertility rates in Africa continue to be among the highest in the world, as many countries there are growing fast, too.

Poverty and health problems due to poor sanitation, lack of access to food and water, the low social status of women and other ills continue to cripple these regions.

Globally, the United Nations estimates that the number of humans populating the planet in will range from as few as 6. Meanwhile, other researchers confirm the likelihood of world population levels flattening out and starting to decline by according to the lower UN estimate. To wit, the Austria-based International Institute for Applied Systems Analysis IIASA recently unveiled research showing that if the world stabilizes at a fertility rate comparable to that of many European nations today roughly 1.

It is difficult to say which way the global population pendulum will swing in centuries to come, given ever-changing cultural, economic and political attitudes and the development demographics they affect.

As such the jury is still out as to whether human overpopulation will become a footnote in history or the dominant ill that stands in the way of all other efforts to achieve sustainability and a kinder, gentler world. We use cookies and other tracking technologies to improve your browsing experience on our site, show personalized content and targeted ads, analyze site traffic, and understand where our audiences come from.

To learn more or opt-out, read our Cookie Policy. In response to a Vox column of mine suggesting that the United States needed a pro—population growth agenda , many readers from across the political spectrum responded by raising fears about overpopulation.

But the truth is that overpopulation in the United States is not even close to a serious problem. Even globally, overpopulation is an overstated problem. How many people can the country support? Because I am an agricultural economist by profession, my bias is to first think about food.

One simple question is how many people can the United States feed? Well, our net agricultural exports account for about 25 percent of the physical volume of agricultural production, which suggests that if we redirected those exports internally, the US could probably support approximately 25 percent more people.

In short, we could feed more than million people , total, merely by consuming locally what we now export. If you assume that a growing population induces more land to be shifted to food production because farming becomes more profitable , that food imports can rise, and that agricultural innovation continues apace, it becomes clear that our land can physically support even more people than that — I estimate as much as double our current population.

And given that agricultural yields are far lower in the developing world today than in the United States, thanks to the much lower level of technological advancement and managerial expertise in those countries, the truth is that the rest of the world has plenty of potential for increased food production: more than enough to feed itself and provide imports for a more populous United States. Merely tweaking foreign land use rules could unlock large gains in agricultural production.

I also approach this problem as a regional economist specializing in migration, so I also think of the American population issue through the lens of population density comparisons. Consider that the European Union has approximately people per square mile, making it as dense as the ninth-densest US state that is, similar to Pennsylvania or Florida. The continental United States on the whole has about people per square mile excluding Alaska, an outlier , making the US less than one-third as densely peopled as the EU.

Yet the European Union, too, has roughly balanced or even slightly positive agricultural trade. That suggests that Europe, too, has no trouble feeding itself despite being three times as densely settled as the United States. If the continental United States were as heavily settled as the EU, the US would have nearly a billion people living in it. Nonetheless, if just the states east of the Mississippi had European-style population density, and the other states maintained current population, then the United States would still have more than million people.

Reducing parking requirements for new apartment buildings, removing height limits, altering restrictive lot sizes namely lot minimums , and generally just allowing landowners to build freely on their property would greatly reduce the cost of living and boost population growth and density. It would prompt Americans to move to denser areas while also lowering housing prices and easing family budgets — which would itself increase fertility.

Recall that many American families wish they could afford more children. The concern with overpopulation, naturally, often dovetails with concerns about climate change. We can answer that question fairly easily, making use of forecasts of population, GDP per capita, and emissions intensity per dollar by country.

We can come up with some scenarios and then compare them to estimates of emissions needed to keep global warming manageable. The greenish lines show emissions under different population scenarios. The most steeply climbing line assumes only a modest decline in global fertility rates, while the lowest green scenario assumes a very rapid decline in total fertility rates — frankly, an unattainable decline.

The teal line assumes that fertility rates in every country go directly to replacement rate in down for most poor countries, up for rich ones , and stay there. The central green line assumes fertility declines in the future following the historic trend.

We are already using the resources of more than one-and-a-half planets. Everyone has the right to a good quality of life and with increasing global affluence, the collective impact of billions more of us will increase even further. This is why we cannot ignore population. The UN's projections show that very small changes in the size of families across the globe make an enormous difference - between a population of 7 billion and an unthinkable 16 billion by the end of the century.

We can achieve a sustainable global population when communities, governments and organisations take action to enable people to choose smaller families through women's empowerment and easy access to high quality education and family planning. By doing so, we can ensure that, in the future, everyone can have a decent standard of living on a healthy planet. Population Matters is putting population on the global agenda, bringing the issue to an international audience through our campaigning , education and research.

Skip to main content. Rapid human population growth exacerbates all environmental problems. We have to address overpopulation More people inevitably put more demands on the planet.

Together, we can do something about it The UN's projections show that very small changes in the size of families across the globe make an enormous difference - between a population of 7 billion and an unthinkable 16 billion by the end of the century. Find out what you can do.