Population growth is easier to manage than per-capita emissions

By Frederick A. B. Meyerson, January 17, 2008

Betsy Hartmann believes that we are not “on the brink of demographic disaster.” I disagree.
We’re already in the middle of a demographic disaster at the global scale in environmental terms. I
concur with John Guillebaud and Martin Desvaux that the world’s population is living beyond its
collective environmental means. Because of the long lag times associated with human demographic
change, we need to act immediately to change that course.

Global per-capita carbon emissions from fossil fuel have remained nearly constant for almost 40
years (currently about 1.2 metric tons [mt] of carbon per person). Therefore, as global population
increases in 2008 by a projected 77 million people, we’ll see an increase of about 92 million mt of
emissions. In effect, in terms of emissions, we’re adding the equivalent of another
Brazil or Australia to
the planet every year.

Just stabilizing total emissions at current levels, while keeping pace with population growth,
would require reducing global per-capita emissions by 1.2 percent each year. We haven’t managed to
decrease per-capita emissions by 1 percent in the last 38 years
combined. The Intergovernmental Panel on Climate Change, former Vice President Al Gore,
and many well-intentioned scientific, media, and activist campaigns haven’t changed that fact. And
because of the rapid economic growth and increased coal use in China and elsewhere, we may now be
headed for
higher per-capita emissions.

We’ve had much more success with managing population. The global population growth rate has
decreased from 2.1
percent in 1970 to 1.2 percent today, as a result of family planning programs and improved
education. If we could reduce global unintended pregnancy rates to the lower levels that already
exist in many European countries, population growth would slow further. As I wrote in my December 3
opening statement, for both environmental and social reasons, we should act quickly to address the
fact that almost 50 percent of U.S. pregnancies are unintended, through improved education and

However, there are large constituencies in favor of high birthrates and continuous population
growth, including religious and business groups. In a
last month,
USA Today reported that the fertility rates in the United Stated rose above 2.1 children
per woman for the first time since 1971, partly as a result of unintended pregnancies in all age
groups. The article also states that a high fertility rate is important to industrialized nations
for social and economic reasons such as social security and job replacement. “Be fruitful and
multiply” also plays well in churches and corporate boardrooms.

In addition, many human rights groups, women’s organizations, and individuals agree with Betsy’s
position that any discussion of population policy in numerical terms necessarily leads to coercion
and racism. This creates an unintentional de facto alliance between those groups and some of the
aforementioned business and religious organizations: They all want to suppress dialogue and
policies that relate specifically to reducing population growth.

Meanwhile, there’s insufficient evidence that population is likely to stabilize with current
policies and funding. Betsy states, “The United Nations projects that world population will
eventually stabilize, falling to 8.3 billion in 2175.” She therefore feels that we don’t need to
worry about population growth. This is an unwise assumption. Long-term population projections (some
only decades into the future) have been notoriously inaccurate. A projection 170 years into the
future is little more than a mathematical exercise, often involving simple assumptions that key
variables such as fertility and mortality rates will converge and remain constant. Constancy is a
state that is rarely, if ever, found in nature.

Joseph Chamie headed the U.N. Population Division for many years. I hope he will discuss the
assumptions behind the U.N. projections in his next posting, and whether or not it is wise to rely
on those projections to make climate policy decisions.

If human history or nature is any guide, I believe there’s a very low probability that fertility
rates will stabilize at the replacement level. It’s more likely that some regions will continue to
experience high fertility and growth. Therefore, if we want to stabilize population globally,
geographical areas with below replacement fertility will also need to exist.

I think it will be easier to reduce unintended pregnancies and births, which we know how to do
successfully through improved reproductive health services and education, than to reduce per-capita
emissions, where our track record is poor. We can achieve this without coercion and also protect
humankind and the planet from the interrelated challenges of population growth and climate


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