How *Not* to Think About Population in the Anthropocene
People have been thinking about the future of world population for hundreds of years, and these thoughts have inspired a whole series of policy interventions, including racially defined immigration barriers, compulsory sterilization, and a global campaign to control population growth. Serious consideration of any new effort to shape demographic trends requires grappling with this history, including what it reveals about past efforts to shape the future.
Alas, what purports to be new thinking about population in the Anthropocene seems strikingly incurious not only about history, but also concepts that are at the core of current policy debates, including demographic projections, an “unmet need” for contraception, and the likely environmental impact of reducing fertility. This risks replicating mistakes that have already caused immense human suffering.
It starts with what all of us are already supposed to know: the future. UN projections are often used as the baseline assumption in advocacy for policies to reduce fertility. Elizabeth Cripps (2021, 1470), for instance, writes that the number of people on the planet “is predicted to reach 10.9bn by 2100. So much we know.”
Cripps was writing in 2021 and citing the UN Population Division’s 2019 World Population Prospects Report. But just one year later, in 2022, the UN revised this “medium projection” downward to 10.4 billion, or 500 million fewer (United Nations 2022). In 2024, it was reduced further to 10.2 billion (UNDESA 2024). And the 2019 projection itself was a downward revision from 2017, when it was 11.2 billion.
None of these are predictions. The Population Division calls them “projections” for a reason. Whether high, medium, or low, they are based on a range of rough and often arbitrary assumptions about future fertility. In 2022, the UN projected the number of births per year in 2100 as anywhere from 77 to 178 million. The medium projection is just the median number among thousands of different scenarios.
The Population Division projections are actually the highest of the four main efforts to project world population. The Intergovernmental Panel on Climate Change does not use them; instead, it bases its climate scenarios on a set of seven projections, with the “most likely” now assuming that world population will peak in 2080 and then decline to 9.9 billion in 2100 (K. C. et al. 2024).
Until 2012, the UN medium projection assumed that every country would eventually converge toward the replacement rate of 2.1 and that no country would have fertility less than 1.85—even those that already had much lower fertility (UNDESA 2014, 15–17). This assumption did not age well. Italy’s fertility rate, for instance, was projected to rise to 1.61 by this point. Instead, it has fallen to 1.18. Spain’s is now 1.12 rather than 1.62 (UNDESA 2013, 75, 77).
This “total fertility rate” cannot answer the most critical question, the one underlying all the recent revisions. It measures childbearing at a given point in time and may therefore increase or decrease because people decide to have children sooner or later in their lives. What we really need to know is whether countries that have seen sustained periods of low fertility will eventually see them rise again. This requires analyzing “cohort” or “completed fertility.” Bhattacharjee et al. (2024, 2076) show that no country in the world has had a cohort with above-replacement fertility after a preceding cohort with below-replacement fertility. Not one.
Most participants in debates about population policy take the medium UN projections at face value. The one important exception is the question of whether fertility rates will continue falling in countries that still have high fertility. But the concern is not about the assumptions or the methodology. As Jane N. O’Sullivan (2021, 580) argued: “Both the projections and the prognosis are highly questionable and are doing a great disservice to women’s reproductive rights and the global prospects for environmental security by undermining political will for eliminating unwanted births and ending population growth sooner rather than later.”
To say that acknowledging population decline threatens reproductive rights is to shoot the messenger. The fact is, two-thirds of the world’s population already live in countries with below-replacement fertility. Over sixty countries are experiencing depopulation. Europe and North America would now have shrinking populations were it not for inward migration from the rest of the world. And this may not persist. O’Sullivan herself frequently takes to social media to criticize policies permitting immigration to Australia.
Other countries, with both left- and right-wing govts, have got their post-pandemic immigration under control.
— Jane O'Sullivan (@OSullivan_Jane) February 23, 2026
Australia now stands alone with the relative size of its migration intake.
Albo is gifting votes to One Nation by refusing to rein it in.https://t.co/zj7VjQN7hr
In a time in which political leaders are beginning to panic about depopulation, advocating for a state role in shaping demographic trends backfires. If current trends continue, pressures mount, and more benign efforts to sustain fertility fail, do we really expect these leaders to opt for further reducing world population? South Korea has spent US$247 billion since 2006 on housing subsidies, direct grants, and child-care vouchers, with no apparent effect (Lee 2024). It has the world’s lowest fertility rate—0.75. Even if the rate recovers to 1, there will be just 16 million South Koreans at the end of the century—less than a third of the current population. Half the country would be seventy-two or older (United Nations 2022).
When Beijing ended the one-child policy in 2016, the fertility rate was 1.77. Then the government began encouraging couples to have children, but it kept falling. Some provinces are offering large cash payments and housing subsidies. But in 2024, there were just 9.5 million births, half as many as in 2016. A state-run survey of tens of thousands of Chinese students found that only about 10 percent thought housing subsidies, tax breaks, and cash payments would make any difference in their own decisions. If China’s fertility rate does not bounce back, its median age will be sixty-nine in 2100, with just 1.2 million births.
To be clear, population decline is not a crisis, an emergency, or a threat. It is possible that sustained low fertility and a drastically reduced human population—in this low-fertility scenario, it would shrink to 200 million by 2300—might make for a better world. A smaller and smaller number of older and older people (with their robot friends) could create an Arcadian ideal, like one big national park or UNESCO heritage site. But we need to be clear if that is the future we want and figure out how to make such a transition, which is unprecedented in human history.
It also shows why reproductive rights must be the foundation for any policy affecting reproductive health care. As established at the landmark 1994 Cairo population conference, the core principle is that people should be able to decide for themselves, without manipulation or coercion, whether and when to have children. And if they want help, they should get it—not just to avoid unwanted childbirth, but also if they need treatment for infertility.
Instead, some invoke reproductive rights while insisting on meeting demographic targets. Jenna Dodson and her coauthors (2020, 4, 6–7), for instance, argue that “rights-based policy interventions could decrease fertility,” which they describe as “the overlooked threat multiplier.” In this way, “reproductive rights” serves as a thin veneer for “strong population-focused voluntary family planning programs” and “population-related policies that focus on reducing desired family size and increasing contraceptive prevalence rates.”
It is not just about language. Dodson et al. illustrate their argument by showcasing the Republic of Korea as a success story. In fact, after taking power in a military coup, President Park Chung Hee did not implement a rights-based approach. Following the advice of Population Council and Ford Foundation consultants, the Korean government set targets for mobile crews who sought to maximize the number of intrauterine device (IUD) “acceptors.” They also gave doctors and “motivators” incentive payments (Connelly 2008, 205–06). Men conscripted into the military were lectured on the importance of having fewer children—first three children, then two, then one. It was a state-led mobilization, one that shifted into high gear when the Park regime declared a state of emergency in 1972 and the president himself set the target fertility rate for the nation (DiMoia 2008).
If such methods are meant to be a model of a “rights-based approach,” then on what principle do we oppose similar policies that identify population decline as the threat and seek to increase desired family size and reduce contraceptive prevalence rates? This is already happening in Iran, the other success story that Dodson celebrates. After the fertility rate fell to 1.8, the Islamic Republic set a goal of increasing it, prohibited instruction in family planning or free distribution of contraceptives, and banned sterilization and abortion (Asadisarvestani and Sobotka 2023).
Those who call for population policies to reduce fertility insist that one can “empower women” just by satisfying the “unmet need” for contraception. Indeed, Elias Ganivet (2020, 4986) argues that “any action taken now could lead to a difference of several billion fewer people by 2100.” To the unwary reader, “unmet need” implies a need for contraception that would-be users express themselves. This is typically estimated based on surveys. But as Leigh Senderowicz and Nicole Maloney (2022) have shown, most do not express an unsatisfied desire for contraception. Instead, they say that they are not actually at risk of becoming pregnant, or they have health concerns, or have religious or philosophical reasons precluding their use. Is this “unmet need”?
Far more than ease of access to contraception, the number of children that couples have reflects how many children they wish to have. And this, in turn, results from larger social trends, above all, the way girls and women have gained access to education. While controversial when this thesis first emerged in the early 1990s, the relative unimportance of subsidizing contraception in changing fertility rates has since been confirmed in several more studies with more data and ever-more sophisticated methods (Pritchett and Summers 1994; Günther and Harttgen 2016).
To be sure, some people still lack access to safe and reliable contraception, and this is especially true for African countries with high fertility rates. But then, these countries also have high rates of infertility from easily preventable or treatable health problems. Infertility treatment is typically available only in private clinics (Afferri et al. 2022). An inability to bear children can have devastating consequences, especially for women, who are often treated as outcasts (Hollos 2008). Might a “rights-based approach” to meeting an “unmet need” therefore increase, rather than reduce, overall fertility rates?
The new literature promoting population policies to protect the environment implies that these women and the children they would like to bear are “threat multipliers.” It often describes the number of people as the critical, but overlooked part of the equation for calculating environmental impact. The rest, seemingly equal to population, is how these people live. They complain that climate scientists neglect population altogether, and they produce charts purporting to show not only that CO2 emissions are correlated with population growth, but that population growth is driving the increase in emissions (Petroni 2009).
But there are good reasons not to focus on changing the number of people on the planet as a way to reduce environmental impact. It’s not mainly because family planning programs have done little to reduce fertility rates, and shifting a long-term trend is hardly a rapid-fire solution in cutting CO2 emissions (Budolfson and Spears 2021). Instead, it is because climate scientists understand that even the simplest estimate of environmental impact, the IPAT equation—impacts on ecosystems (I) are the product of the population size (P), affluence (A), and technology (T)—includes affluence, i.e., consumption per person, and technology, especially how energy is generated, and not just population. When climate scientists calculate just one kind of impact, CO2 emissions, they use at least four different factors, and population is just one of them. The other parts of what is known as the Kaya identity model are GDP per capita, the energy intensity to generate GDP, and the emission intensity of that energy.
While all of these factors can act as multipliers, the data show that an increase in GDP per capita has been key. In the period between 1978 and 2018, when China’s population increased by 45 percent, economic growth was more than ten times more important in making it the world’s largest producer of CO2 emissions (Zheng et al. 2020). In Southeast Asia, the increase in GDP per capita has been eight times more significant than the increase in population (Chontanawat 2018). In India, it is almost five times more important (Ortega-Ruiz et al. 2020).
Moreover, reducing fertility can actually increase environmental impact. Societies with fewer children and older people use more square footage per capita (Lamb et al. 2021). The number of households worldwide grew much faster than the number of people, even during peak population growth, and this is what mainly determines resource consumption and biodiversity loss. A larger population in which multiple generations tend to live under one roof will have less of an impact than one composed of small nuclear families, couples, and people living alone (to say nothing of second homes) (Liu et. al. 2003).
This brings us back to how, specifically, “rights-based policy interventions could decrease fertility.” Those who insist that family planning programs have a great impact have long maintained that they can induce demand for contraception and abortion and not just increase supply (Bongaarts 1994). Historically, the main strategy has been to promise that having fewer children will allow people to have more things, i.e., a consumerist, energy-intensive lifestyle. Some might call this a threat multiplier.
So what is the plan for family planning, if it now aims to reduce consumption? Some advocates, such as Martin Kolk (2021), acknowledge that affluent societies are mainly responsible for threats to the environment and biodiversity and therefore argue for making it harder and more expensive to have children. When we recall that policies such as paid parental leave have had little effect on fertility rates, eliminating them might make little difference on family size. But this will almost certainly have a significant negative impact on both maternal and infant health (Heymann et al. 2017), and advocates of environmentally friendly population policies should be clear about that.
Time and again, population policies and programs have not had a substantial and sustained impact on fertility rates, have sometimes resulted in great human suffering, and have often had unintended consequences. These consequences include skewed ratios of women and men resulting from sex-selective abortions and widespread mistrust of vaccination programs that are suspected of causing sterilization. We cannot begin to know how and why this time might be different, and better, without engaging with this record.
Alas, that is not what is happening. Instead, those who advocate for population policies find the history of earlier such efforts to be “vexing,” but they cannot agree on why. For Naomi Oreskes (2023), the answer is simple (mostly): “Population control is a vexing subject because in the past it has generally been espoused by rich people (mostly men) instructing people in poor countries (mostly women) on how to behave. Prior attempts at limiting population surges have been tainted by racism, sexism and class prejudice.”
In fact, there is a large and growing body of work showing how men and women in rich and poor nations formed alliances to advocate for population policies for a range of reasons, oftentimes to use them to achieve the national goals of newly independent countries. Many thought that they were saving humanity, or saving the Earth, and they eventually succeeded in creating a worldwide campaign that had the approval of the United Nations and a host of the world’s leading scientists and intellectuals (Solinger and Nakachi 2016). It is absolutely true that in their heyday in the 1960s and 1970s, family planning NGOs and think tanks tended to be dominated by men, and almost all the funding came from the United States. But they would have gotten nowhere if, for their own racist and sexist reasons, racist and sexist men merely instructed poor women in how to behave.
Diana Coole (2021, 1454–55), by contrast, describes this same period as a golden age. “Between the mid-1960s and 1970s, a lively counter-culture envisaged societies predicated on stability rather than expansion.” At that point, population policies were “associated with economic equality and women’s emancipation.” Opposition came only later: she identifies 1974 to 1994 as “the crucial period when hostility to population policies developed,” when “they were increasingly dismissed as racist and misogynist.”
In fact, it was in the late nineteenth and early twentieth centuries that advocates for causes such as early sex education and nondiscrimination based on sexuality were most influential. They were largely purged in the 1930s and 1940s. By the 1960s, what had become a movement to control world population was captured by wealthy foundations and international aid agencies. Program officers and their senior leadership were hardly motivated by economic equality or women’s emancipation. Instead, Cold Warriors raised almost all the money and did so for the explicit purpose of preventing revolutions and accelerating “modernization.” When they spoke about women, they often called them “targets” and “acceptors.” The women professionals who fought their way into these foundations and aid agencies in the 1970s and 1980s had to overcome appalling misogyny. (It was not easily dismissed [Connelly 2008].)
For Coole, this period was one of “toxification.” Similarly, Oreskes refers to racism and sexism as having “tainted” attempts to limit population growth. Both imply that at some point there was a pure, untainted population discourse. If only this were true! In fact, any policy is an exercise of power, and power reflects and sometimes reinforces social and political hierarchies. Why would we expect policies to shape the population of the world, whether in the past, present, or future, to be any purer than the people producing them?
Purity is particularly unlikely when the number of people on the planet is said to represent “a crisis,” and when it is alleged that action is required to avert “imminent existential threats.” This discourse strengthens those who already have power, ostensibly so they can keep the rest of us safe. It silences those who have concerns that seem less existential. It can authorize actions that would otherwise be immoral, illegal, or unimaginable. Above all, it can make the past seem passé (Aradau and Van Munster 2011). In the long history of population policies, these periods of “crisis” or “emergency” are precisely when the worst abuses occur.
This is not how to think about population in the Anthropocene, because it actually makes it harder to think more deeply and to learn more fully. And we must learn from this history if we want to develop policies that can actually protect both people and the planet, especially when both hang in the balance.