Have you heard that we’re getting new neighbors? Demographers expect that the number of people living on earth—now about 6.8 billion—will grow to between 8 and 11 billion by 2050.

Whether population tops out at the high or the low end of those projections will have a huge impact on climate change. So population control is again claiming a place on the environmental agenda.

(Photo: Nairobi slums)

Oops! Did I say “population control”? I should have said “addressing population growth” or “assuring reproductive rights for women” or even “securing population justice” — because some people get very nervous when environmentalists start talking about population, and for good reason.

Yet the conversation is worth having, which is why I went to a discussion today at the Center for American Progress in Washington featuring Laurie Mazur, the editor of a new book called A Pivotal Moment: Population, Justice & The Environmental Challenge (Island Press, $30).

Mazur argues that we are at a pivotal moment, not just environmentally, because of the lethal overheating of the planet, but demographically, because, as she writes,

the ultimate size of the human population will be decided in the next decade or so.

That’s because right now the largest generation of young people in human history is coming of age. Nearly half the world’s population—some 3 billion people—is under the age of twenty-five. Those young people will, quite literally, shape the future.

Like it or not, population is an environmental issue. Although many of our new neighbors will live in such poor countries as India, Bangladesh and Indonesia, they will have carbon footprints, too, albeit much smaller ones that those we make here in the U.S.

“Does population, per se, matter for the environment?” Mazur asked at the Center for American Progress. “Yes, it does.” It will matter even more as poor people improve their standard of living, gaining access to automobiles, electricity, computers and big-screen TVs. “Our planet can’t sustain 7 billion people consuming as we do, much less 9 or 11 billion,” she says.

What is to be done? It’s no mystery. “Over the last 50 years, we’ve learned a huge amount about how to slow population growth,” Mazur says. Quite simply, the goal should be to provide people with the means and the power to make their own decisions about when to have children. Women first need access to family planning and reproductive health services. Beyond that, they need to be able to determine their own fate. That means confronting gender inequality, providing girls with education, ending child marriage and reducing global poverty.

It’s a daunting agenda but  the first step–providing reproductive health services for every woman on earth—is surprisingly inexpensive. The developed countries’ share of that cost is about $20 billion, according to Mazur, and she pegs the U.S.’s share at about $1 billion, less than the daily price tag of the war in Afghanistan.

The benefits are significant. Stabilizing world population at 8 billion, rather than 9 billion or more, would reduce greenhouse gas emissions by one gigaton or more by 2050, the equivalent of one or more of the “wedges” in the well-known analysis of climate mitigation by Princeton professors Stephen Pacala and Robert Sokolow, according to Brian C. O’Neill, a scientist at the National Center for Atmospheric Research, who contributed a chapter to A Pivotal Moment.

Nevertheless, environmentalists tiptoe around the population issue for a couple of reasons, says Andrew Light, a senior fellow at the Center for American Progress. The first is that the apocalyptic warnings about overpopulation that were sounded in the late 1960s when the Sierra Club published Paul Ehrlich’s The Population Bomb proved unfounded.

The other reason for trepidation is political sensitivity. Environmentalists don’t want to be seen as caring more about nature than people. The word “misanthropic” came up during the discussion, as did the names of Edward Abbey and David Brower. Whatever you think of Abbey, he was not a social animal.

Environmentalist are also aware of the ugly history of “population control.” While the international family planning movement brought contraceptives to the developing world and drove down fertility rates down between the mid-1960s and mid-1990s, family planning programs were controversial, as Mazur notes:

Some–notably in India and China–flagrantly abused human rights with coercive practices such as forced sterilization and abortion (which continue to this day in China). And many first-generation programs focused more on demographic “targets” than on individual needs.

In the U.S., the Federation for American Immigration Reform, or FAIR, an organization seen by many as hostile to immigrants, was founded by members of the Sierra Club and John Tanton, then president of Zero Population Growth, which advocated birth control and tax incentives to limit population growth, according to A Pivotal Moment. In 2007, an Australian medical journal advocated a $5,000 carbon tax per child for families with more than two children.  And, just a few weeks ago, Rush Limbaugh suggested, facetiously, that Andrew Refkin, the distinguished climate change reporter for The New York Times, kill himself after Revkin mused in print about the possibility of awarding carbon credits for avoided children, much like they are awarded for avoided deforestation. So, yes, talking about population is a tricky business.

Two final thoughts. First, while curbing population will help mitigate global warming, that is not the same thing as saying that population growth caused the climate crisis. Overconsumption is by far the bigger culprit, with Americans way out in the lead. The Washington, D.C., area, Mazur said, produces 25% more CO2 than all of Sweden, which has nearly twice as many people.

Second, the idea of “population justice,” which emphasizes individual freedoms to make decisions about sexuality, reproduction and family, should help avoid the future use of coercive tactics. As Light put it: “Any method you want to use for decreasing population has to pass some obvious moral tests.” Better yet, providing parents with access to family planning, educating girls and dealing with gender inequality are all steps worth taking for their own sake, regardless of their impact on population. You can read more at The Population Justice Project and at the Women’s Environment and Development Organization.

So is paying people not to have children moral? Comments, anyone?