Population Matters

A Tale of Two Studies

August 10th, 2009

Two studies released this month–one demographic, the other environmental–pose significant questions for those concerned about the future of the planet.

The demographic study (“Advances in Development Reverse Fertility Declines”), published in the August 2009 edition of Nature, suggests that rising levels of economic and human welfare in highly developed nations may be leading to higher, not lower fertility rates.

The environmental study (“Reproduction and the Carbon Legacies of Individuals”), published in the August 2009 edition of Global Environmental Change, reports that having a child in the U.S. significantly increases an individual’s carbon “legacy” or footprint.

Taken together, these two reports suggest that efforts to reduce greenhouse gas emissions may be facing a tougher than expected demographic challenge.

It has long been assumed by many that rising global prosperity (while increasing per capita consumption of resources) ultimately leads to lower birth rates and thus may contribute to a more–not less–sustainable world. That may be true for the developing world, but the Nature study suggests that it’s not true for many economically advanced nations. The authors of the report conclude that:

Whereas a decade ago Europe, North America and Japan were assumed to face very rapid population ageing and in many cases significant population declines, our findings provide a different outlook for the twenty-first century. As long as the most developed countries focus on increasing the well-being of their citizens, and adequate institutions are in place, the analyses in this paper suggest that increases in development are likely to reverse fertility declines—even if we cannot expect fertility to rise again above replacement levels. As a consequence, we expect countries at the most advanced development stages to face a relatively stable population size, if not an increase in total population in cases in which immigration is substantial.

The study appears to suggest that as incomes rise in advanced nations, many couples decide that they can afford to have a larger family size…and do. That conclusion appears consistent with earlier reports from Western Europe that the family size of households where both husband and wife work is trending higher than in households where only one spouse works.

These findings may help to allay fears of a sharp population decline in Western European and other economically advanced nations, but what does it mean for environmental concerns about greenhouse gas emissions and resource depletion?  Higher than anticipated population levels in wealthy countries could make the transition to a more sustainable world even more difficult to achieve.

The Oregon State study that appeared in this month’s edition of Global Environmental Change estimates that an environmentally conscious person in the United States could save about 486 tons of CO2 emissions during their lifetime by taking such steps as driving less, increasing their car’s fuel economy, and replacing single-glazed windows with energy-efficient windows. But, if that person “were to have two children, this would eventually add nearly 40 times that amount of CO2 (18,882 t) to the earth’s atmosphere.”

The authors went on to stress that, “This is not to say that lifestyle changes are unimportant; in fact, they are essential, since immediate reductions in emissions worldwide are needed to limit the damaging effects of climate change that are already being documented.” The authors concluded, however, that, “Ignoring the consequences of reproduction can lead to serious underestimation of an individual’s long-term impact on the global environment.”

The great tragedy, of course, is that even in economically advanced nations, there are still many women who want to reduce their fertility, but who lack access to, or adequate knowledge of, modern methods of contraception. In the U.S, where fertility rates are on the rise again, teenage pregnancy rates are climbing again after a 14-year decline. So even if the desired family size is increasing, there is still much that can be done to prevent unwanted and unintended births. And doing so is a both a human and an ecological imperative.

Posted by Robert J. Walker, Executive Vice President

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