7 Billion: what does it mean for global population trends?

Originally posted January 2012

population growth chart

This past summer the Population Division of the United Nations projected that the world would soon welcome its 7 billionth resident. The date arbitrarily selected to mark the event was October 31, 2011. By happy circumstance, on October 31 Benjamin Oliver McDaniel was born to Carolina Population Center staff member Phil McDaniel and his wife, Sarah – perhaps world citizen number 7 billion (give or take some large numerical uncertainty in the projection).

McDaniel babyBeyond congratulations and well wishes to the McDaniel family, what meaning does such an event have for a university center of research scholars, like CPC, devoted to understanding and interpreting global population trends? Interim Director of CPC, Paul Voss, was asked to reflect on this question. "Many will argue that we can dismiss the UN announcement as mostly an event intended to engage the world's media outlets," says Voss. "But it's more than that. To begin with, it's a reminder to many of us who entered the field of demography 30 to 40 years ago why we chose to study population." Voss continues, "This was a time when the world's population was roughly half what it is today, but it was a time of distressingly high worldwide population growth rates. Thoughtful voices were raised regarding the earth's ultimate carrying capacity and asking, as did Thomas Malthus almost 200 years earlier, whether hungry mouths to feed were outstripping food production."

Dr. Voss suggests another reason to reflect on the UN population event. "For most scientists working in the field of population studies, focusing on a single number misses the point. It serves to remind us how quickly really important population-related issues can get buried by the ‘number stories.' Much more important is the huge range of social and environmental issues lurking beneath the number." Voss suggests these issues include:

  • The dishearteningly dire quality of daily life for billions of people around the globe and the extent to which poor nutrition, lack of accessible health care, poverty and violence are shared so unequally across the world's regions
  • The extent to which the hopes and dreams of a better life for one's children simply lie out of reach of hundreds of millions of families primarily, but not exclusively, in the developing world
  • The pressures that increasing populations put on many of the world's non-renewable natural resources, and the pollution of the water we drink, the air we breathe and the fields from which we obtain our food

"Most important of all," says Voss, "is trying to gain a clear, scientifically grounded understanding of these issues and trends. Are the changes in each of these areas pointing to a better or worse tomorrow? A more polluted world; or less? A world where fewer children go to bed hungry; or more? A world where the advantages of wealth and the burdens of poverty are more equally distributed; or less equally?

"The Carolina Population Center is one of the leading institutions in the world providing answers to some of these questions," says Voss. "Our researchers are devoted to better understanding these issues and providing answers to these questions. Research on health disparities and population-environment interactions are among the signature research themes of the CPC."

More than 100 faculty, postdoctoral scholars and predoctoral trainees are engaged in such research at the CPC. Among these are Dr. Clark Gray of UNC's Department of Geography and Dr. Clare Barrington of UNC's Department of Health Behavior and Health Education.

As the world population surpasses 7 billion and heads towards a projected peak at 10 billion, many are asking whether the earth will be able to support that many people and what the consequences of population growth will be for biodiversity and ecosystem services.

The research of CPC Fellow Gray directly addresses these issues, with a focus on the consequences of environmental change for human migration and the consequences of demographic change for tropical deforestation. As rural populations have grown in the developing world and evidence of climate change has mounted, many scholars and practitioners have raised concerns about the plight of "environmental refugees" displaced from vulnerable areas. To place these discussions on a sounder scientific footing, Gray and colleagues have used longitudinal survey data on migration and a variety of environmental data sources to investigate this process in Ethiopia, Kenya, Uganda, Ecuador, Indonesia and Bangladesh. The results suggest that adverse environmental conditions tend to increase migration, but these movements are often short-distance or temporary, and reductions in mobility are also possible.

Regarding the consequences of population growth for biodiversity, Gray and CPC Fellow Dr. Richard Bilsborrow are collaborating to investigate the drivers of land use change in forested indigenous communities of the Ecuadorian Amazon. In other contexts indigenous communities have been shown to serve as an effective form of forest protection, but a 2001 baseline study by Bilsborrow and Flora Lu revealed a subset of these communities to have very high fertility and to have adopted market-oriented land use strategies. In spring 2012, Gray and Bilsborrow will conduct follow-up data collection to assess how indigenous land use and livelihoods have changed since 2001 and what the consequences have been for household well-being and environmental conservation.

CPC Fellow Clare Barrington's research addresses issues underlying health disparities among migrant populations in the US. North Carolina has one of the fastest growing Latino populations in the US, largely due to economic opportunities in the service and construction industries. While the benefits of migration to individuals, families, and both sending and receiving communities can be numerous, the health of migrant populations does not always follow a positive trajectory. To improve understanding of the disproportionate burden of HIV/AIDS among Latinos in the US, Barrington conducted a qualitative study, with Dr. Lisa Hightow-Weidman from the UNC School of Medicine. With funding by the UNC Center for AIDS Research, they collected life histories of Mexican men living with HIV in North Carolina. Topics explored in the life histories include early life experiences, family and social network dynamics, migration trajectories, HIV-related risk behaviors, and experiences living with HIV. By examining the entire life history of HIV-infected Mexican men, Barrington and colleagues were able to obtain a more holistic understanding than traditional survey approaches of the interplay between migration and HIV through the life course.

One of the clear themes to emerge from the interviews was that nearly all participants became aware of their HIV status once their infection was already quite advanced, reflecting barriers to early diagnosis among this migrant population. Late diagnosis has negative implications for the health of the infected individual as well as for ongoing transmission of the virus. In response, Barrington and colleagues are embarking on a new study, with funding from the UNC EXPORT program, to assess the effectiveness of using social network referrals to promote free and confidential HIV testing among Latino men in Durham, NC. Lessons learned from this study will guide new innovative approaches to improve early HIV testing among Latino men and provide timely linkages to care and support services.

Paul Voss

"In summary," Voss says, "the crossing of a population threshold like 7 billion serves as a reminder of the many significant ways our CPC colleagues and Center support staff are dedicated to understanding global population trends with a trained eye toward influencing better social, economic, environmental and health policies around the globe and toward improving the lives of the world's citizens." He continues, "These are daunting challenges. Over the next 40 years, another two-plus billion persons are projected to be added to the world's population – most of them in the less-developed parts of the world, regions already struggling with matters of intense local need and sustainability." To highly personalize it, says Voss, "Exactly how well we meet these challenges will have an enormous impact on the world we leave behind for young Benjamin McDaniel and the other 400,000 other babies born on his birth date."


The Carolina Population Center is a community of leading population scholars collaborating on interdisciplinary projects to promote population related discovery, learning and communication. CPC faculty and students work together on path-breaking research to address population issues in 85 countries and across the US, as well as locally, in central North Carolina. Based at the University of North Carolina at Chapel Hill, the center is rich in expertise, with 61 active faculty fellows (representing 15 departments in 5 schools or colleges), 59 predoctoral and postdoctoral scholars, and a highly skilled staff.


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