Human population, led by Africa (in part through paucity of family planning), likely to be on the up and up through 2100, new analysis finds (Science): 

Global Population Won’t Stabilize This Century
A new report suggests that contrary to past projections arguing that global population will peak around 2050, the world’s population is unlikely to stabilize this century. The results, based on a statistical analysis of the most recent population projections from the United Nations (UN), point to Sub-Saharan Africa as the primary engine driving this unexpected growth through 2100. Patrick Gerland and colleagues applied advanced techniques to the latest UN data to estimate future demographic trends — like fertility and life expectancy — with great accuracy. They estimate an 80% probability that the world population, now 7.2 billion, will increase to between 9.6 and 12.3 billion by 2100. The main reason for this is an increase in the projected population of Africa, the researchers say; demographers had projected that fertility in Africa would decline, but Gerland et al.show that levels of fertility throughout the region are persistently high. Furthermore, many African women are still having larger families (median 4.6 children), in part due to lack of contraceptives. Mortality from HIV has been reduced in Africa, too, further contributing to population growth. The ratio of working age people to older people is almost certain to decline substantially as well. Because rapid population increase in high-fertility countries can create challenges ranging from depletion of natural resources to unemployment to social unrest, the results of this study have important policy implications. The projected population growth could be moderated, the researchers say, by more substantial investments in girls’ education and family planning programs that provide contraceptives; both factors influence fertility. The UN’s population reports, published every two years, feature “high” and “low” projections that have been criticized for lacking a probabilistic basis.

Article #21: “World population stabilization unlikely this century,” by P. Gerland; N. Li; D. Gu; T. Spoorenberg; J. Wilmoth at United Nations in New York, NY; A.E. Raftery; H. Ševčíková; N. Lalic at University of Washington in Seattle WA; L. Alkema at National University of Singapore in Singapore; B.K. Fosdick at Colorado State University in Fort Collins, CO; J. Chunn at James Cook University Singapore in Singapore; G. Bay at Latin American and Caribbean Demographic Center (CELADE), Population Division of the United Nations ECLAC in Santiago, Chile; T. Buettner; G.K. Heilig, independent consultant. 

The @PopulationMedia Center is questioning some conclusions of the population analyst Joseph Chamie in my post on Japan’s great diaper shift. (The aging country’s adult diaper demand is almost outpacing the market for baby diapers.)

Here’s a note circulated by Joseph Bish of the Center:

I thought today might be an easy one, but was immediately confronted by a challenging post by Andy Revkin at his Dot Earth Blog. In it, Andy reflects on his experience in Japan this fall, and brings up some data indicating the population of Tokyo may peak by 2020 before moving into the notorious "diaper-dynamic" of Japan (wherein adult diapers are close to selling at the same number as infant diapers in the country). This compels him to reach out to Joe Chamie, who reinforces the notions set forth in a 2010 essay Chamie wrote titled "Global Population of 10 Billion by 2100? - Not So Fast." In sum, Chamie believes that:


1. fertility will come down from high levels more quickly than expected;
2. fertility will remain below replacement level in low fertility nations;
3. world population unlikely to reach 10 billion by century’s end.

There are several areas worth remarking on here. First, Chamie’s initial assertion is at least partially called into doubt by the recent upwardly revised UN Population Projections. For example, here is John Wilmoth, Director of the Population Division in the UN’s Department of Economic and Social Affairs. "In some cases, the actual level of fertility appears to have risen in recent years; in other cases, the previous estimate was too low."For the full UN press release click here (PDF). Also, please note the UN is projecting 10.85 billion by 2100 for the medium variant, not 10 billion as Chamie indicates at the end of theDot Earth post.

Next, Andy relays Chamie’s thoughts that family sizes in high fertility countries of Africa and Asia will continue to decline because of "increasing urbanization, smaller and costly housing, expanding higher education and career opportunities for women, high financial costs and time pressures for childrearing and changing attitudes and life styles." This is a very different “picture” than many of us are familiar with. (In that light, I have re-ran an essay by the President of Worldwatch Institute, Bob Engelman, which was published in Yale360 this summer.

Overall, its not clear to me if the Dot Earth blog goes into the naughty or nice category. But, at any rate, it is good food for thought. And, on that note — Merry Christmas. May we continue towards the ideal of Peace on Earth.

"If behavior and technology do not change, more numerous humans will trample the earth and endanger our own survival. The snake brain in each of us makes me cautious about relying heavily on changes in behavior. In contrast, centuries of extraordinary technical progress give me great confidence that diffusion of our best practices and continuing innovation can advance us much further in decarbonization, landless agriculture, and other cardinal directions for a prosperous, green environment. For engineers and others in the technical enterprise the urgency and prizes for sustaining their contributions could not be higher. Because the human brain does not change, technology must."

— Jesse Ausubel of Rockefeller University on a path toward fitting people on a finite, thriving planet

How youth bulges in turbulent poor places feed unrest. Eye-opening @KennethWeiss series on population continues. 

How youth bulges in turbulent poor places feed unrest. Eye-opening @KennethWeiss series on population continues. 

Population unmentionable in many environmental quarters, but condom push by biodiversity group breaks mold. Ultimate green technology?

Population unmentionable in many environmental quarters, but condom push by biodiversity group breaks mold. Ultimate green technology?

Amazing inflammatory @Guardian "green helmet" spin on a German proposal for the UN Security Council to produce a report on security implications of climate change. The request is fine, but only if the full suite of parallel drivers of vulnerability is considered.

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China moves from human census — 1.34 billion — to panda census — 1,596 at last count. (Photo: Liu Jin/AFP-Getty Images)

China moves from human census — 1.34 billion — to panda census — 1,596 at last count. (Photo: Liu Jin/AFP-Getty Images)

Happy Mother’s Day. May all mothers’ needs be met - for education, for the freedom to choose family size and more. More from Dot Earth on women, families and the human journey. (Photo: apple blossoms in the back yard.)

Happy Mother’s Day. May all mothers’ needs be met - for education, for the freedom to choose family size and more. More from Dot Earth on women, families and the human journey. (Photo: apple blossoms in the back yard.)

On @EarthSky my Q&A with @Jorge_Salazar “There’s every chance the next 30-year period will be one of great innovation and collaboration around the world. It just takes a little bit of focus to get you engaged in the conversations and the actions that are needed for brighter outcome. The rest.