The Impact of American Family Size Decisions on CO2 Emissions

September 18, 2009 • Daily Email Recap

On August 5, Lou Dobbs ran a story on how overpopulation is a major contributor to greenhouse gas production and the finding by researchers at Oregon State University (OSU) that having one less child in America produces a much bigger savings in CO2 emissions than things like changing light bulbs and driving more efficient automobiles. See the Dobbs interview with Prof. Paul Murtaugh and Ben Zuckerman of UCLA and CAPS at or read the transcript attached. To send a comment to Lou Dobbs, visit

Pasted below is the press release from OSU. Attached is the OSU paper, “Reproduction and the carbon legacies of individuals.” It is one of the most important papers for those of us working in the population field to appear in some time, and I urge you to read it even if you find the mathematical formulas used difficult to understand. It bolsters arguments many of us have been making that addressing population growth is absolutely necessary to solve the climate crisis.

As I read the paper, I realized that one of the assumptions may be optimistic. Specifically, assuming that all descendents will adopt the medium-variant fertility whether they come from mothers of large families or mothers of small families does not take into account what one could call the “Utah phenomenon.” Those who grow up in large families have as their primary role models parents who chose to have many children, and to the extent they model their behavior after their role models, I suspect they are more likely to have larger families than those who grow up in small families. They may be further influenced by cultural and religious factors to have larger families than the norm. I don’t know if this has been studied, but family size traditions are often consistent within cultures.

Major newspapers and magazines have picked up this story, which you can read at the following links:

Family planning: A major environmental emphasis

Some people who are serious about wanting to reduce their “carbon footprint” on the Earth have one choice available to them that may yield a large long-term benefit – have one less child.

A study by statisticians at Oregon State University concluded that in the United States, the carbon legacy and greenhouse gas impact of an extra child is almost 20 times more important than some of the other environmentally sensitive practices people might employ their entire lives – things like driving a high mileage car, recycling, or using energy-efficient appliances and light bulbs.

For full article, visit:

Current World Population


Net Growth During Your Visit