Why is it so Hard to Talk About Population? A Personal Story

Climate Change and Population

For many years, when I gave talks around the world about climate change and the Anthropocene, I did not talk about population. I had long listened as climate scientists, when asked what we should do about climate change, offered the answer: “Address population growth.” That made no sense. Indeed, it felt like a non sequitur, because I knew that population growth was not the primary, or even the major, driver of anthropogenic climate change. Climate scientists were focusing on the wrong thing. 

The main driver of anthropogenic climate change is greenhouse gas emissions, mostly from burning fossil fuels. More than half of all carbon pollution in the atmosphere has been emitted since 1990, and the bulk of this carbon has come from the economic activities of about a dozen wealthy, industrialized countries, mostly in North America and Europe (Stainforth and Brzezinski 2020). But since 1990, these countries have had very low birth rates. The Organisation for Economic Co-operation and Development (OECD) average fertility rate since 1990 has hovered below 2.0, and since 2000, mostly below 1.7. In 2022, the OECD average was 1.5 (OECD 2024). 

In Japan, until recently one of the few non-Western countries to contribute substantially to climate change, the fertility rate bottomed out in 2005 at 1.26; it has held steady at about 1.3 to 1.4 since then. In South Korea, as of 2025, it was a mere 0.74 (Jie 2025). Taiwan is about the same. Assuming a replacement rate of 2.0 for a stable population, this means that apart from immigration, the population of most wealthy countries has been falling during the time when atmospheric concentrations of greenhouse gases have been rising (Craig 1994). 

In contrast, countries with very high fertility rates (and significant endogenous population growth)— such as Niger, Somalia, Chad, Nigeria, and South Sudan—were poor, with very little greenhouse gas emissions to the atmosphere (Ritchie 2023). These countries were mostly in sub-Saharan Africa—with mostly Black citizens. Talking about population growth diverted attention from the Global North (where the cause lay) to the Global South (where it did not). It illogically focused attention on people who were not responsible for the climate problem and unethically shifted the blame from (mostly) wealthy white people to (mostly) poor people of color. To cite just one statistic: In 2019, the top 10 percent of emitters were responsible for 48 percent of global emissions, whereas the bottom 50 percent were responsible for just 12 percent (Chancel 2022). For the most part, these uber-emitters are wealthy people living in wealthy countries, where population growth rates are low or even negative. My reluctance to talk about population was not reticence; it was logic. Let’s keep the focus, I thought, where it rightly belongs. 

A few years ago, my thinking began to shift. As a member of the Anthropocene Working Group, I participated in many conversations on the evidence of human impact recorded in the stratigraphic record (Waters et al. 2016). This evidence often reflected the effects of climate change, such as the changing isotopic composition of coral reefs due to warming oceans, but it was not limited to climate change (Hetzinger et al. 2016). It also reflected myriad other human impacts on the environment, including radioisotopes from nuclear weapons tests, widely dispersed microplastics (including in our bodies), and the changing distribution of species on the planet. 

While the statistics on energy and plastic use are dominated by the wealthy countries of the Global North—where population growth is not a problem— the loss of biodiversity driven by habitat destruction is a global problem. Climate change contributes to biodiversity loss, but the primary driver of habitat destruction is not greenhouse gas emissions. It is human encroachment. 

Here, the poorer countries are implicated, and population pressure is one reason. I decided the time had come to talk about population, not so much in the context of climate change per se, but in the context of the polycrisis to which the Anthropocene neologism rightly refers. I found myself thinking of the famous lines from Lewis Carroll (1871) that the time had indeed come to talk of many things, including not only why the sea is boiling hot, but also why so many creatures in it are being crowded out. 

“The time has come,” the Walrus said, / “To talk of many things: / Of shoes—and ships—and sealing-wax— / Of cabbages—and kings— / And why the sea is boiling hot— / And whether pigs have wings.”

My Intervention in Scientific American 

For five years, I wrote a monthly column for Scientific American magazine, and in early 2023, I wrote “Eight Billion People in the World Is a Crisis, Not an Achievement” (March 1), based in part on my 2021 book, Science on a Mission. 

In that book, I argued that US Navy funding of oceanographic research had led to an asymmetric emphasis on the physical, rather than the biological aspects of oceanography. I noted that in 2006, one scientific study predicted the collapse of all wild food fish populations by 2050 (Worm et al. 2006; see also Dean 2006). In 2012, the United Nations reported that more than half of global fisheries were exhausted and a third of critical marine environments destroyed (Ki-moon 2012). 

No one wants to say that all is lost, so most reports on biodiversity in recent years have stressed that there is still time to save marine life, particularly since only a tiny fraction of the ocean is currently protected. While the destruction of ocean ecosystems has many causes, in my book, I argued that scientific neglect did not help combat them. And cultural neglect—that is to say, a lack of widespread knowledge and discussion of marine biodiversity loss—is clearly also part of the problem. 

The impetus to say something about terrestrial habitat destruction and its relation to biodiversity loss came in late 2022, when three things happened around the same time. In November, the global human population passed 8 billion. In December, representatives of 188 governments adopted the Kunming-Montreal Global Biodiversity Framework, promising to conserve and manage at least 30 percent of the planet for biodiversity and to restore 30 percent of currently degraded ecosystems (United Nations 2022). 

Those were the first two, and I wanted to point out that these two developments—population growth and biodiversity loss—are linked, because (as already noted) the major driver of plant and animal loss is habitat destruction caused by human encroachment. (This may also drive zoonotic pandemics, but that is another matter.) Scientists have made this connection clear. The Royal Society (2026), for example, has observed that the growing global population “has meant that ever more natural habitat is being used for agriculture, mining, industrial infrastructure and urban areas.” According to the International Union for Conservation of Nature, more than 45,000 species are threatened with extinction, including 41 percent of amphibians, 37 percent of sharks and rays, 36 percent of reef-building corals, 34 percent of conifers, 26 percent of mammals, and 12 percent of birds (IUCN 2025). The Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) has put the number far higher, perhaps as high as a million species (UN Environment Programme 2019). Even species that humans have created are at risk: at least 1,000 breeds of mammals used for human food and agriculture are threatened (UN Environment Programme 2019). 

Agriculture is a big part of this story. According to UN estimates, more than a third of the world’s land surface and nearly 75 percent of freshwater resources are now devoted to crop or livestock production (UN Environment Programme 2019). As the world population continues to grow and there are more and more mouths to feed, the problem will likely worsen. Unless agriculture becomes radically more efficient (and we’ve tried that, with well-known mixed results), the allocation of resources to crop foods and animals will have to grow at the expense of natural habitat and therefore biodiversity. Increased efficiency, without guardrails, will not guarantee less or better land use. The introduction of genetically modified crops, for instance, is an excellent example of the Jevons paradox, which states that increased efficiency may increase demand for a resource. Even though GM crops are highly efficient, their use has been coupled with increased production of corn and soy, further contributing to biodiversity loss (Flachs et al. 2025). Population gain and biodiversity loss are two sides of the same story.

Those were the first two things. The third was this: some media outlets presented the population milestone as a good thing. More than that, as something to celebrate. On November 19, 2022, The Washington Post ran an editorial under the banner “The world’s population is 8 billion and rising. That’s probably a good thing.” (For comparison, the global population stood at 3 billion in 1960 [World Bank 2018]). The argument was the Panglossian claim that more people meant more brainpower available to solve the world’s challenges: 

Too often in the past, conventional wisdom about population growth has tended to be pessimistic—even apocalyptic. In 1798, British economist Thomas Malthus forecast that an increasing population would soon outstrip, disastrously, nature’s capacity to feed so many people; in 1968, the title of an influential tract spoke of a “population bomb.” And yet here we are: The world’s population has octupled since Malthus’s day, more than doubled since 1968, and living standards around the world have vastly, though unevenly, improved during that time. 

This is a standard argument among conservative commentators and economists known as cornucopians. Malthus was wrong, they argue, because he failed to appreciate the power of innovation, particularly technological innovation in a free-market economy. With an ever-increasing population, the editorial continued, “millions of new people—with their new ideas and fresh energy— are on the way.” This, they insisted, will spur the innovation needed to solve our pressing problems. Moreover, problems create the pressure to find their own solutions, as the “scramble for resources”—in other words, competition—creates “not only scarcities and conflicts,” but also “incentives to overcome them through innovation” (Washington Post Editorial Board 2022). Let creativity flourish, and all will be well. No need to fret. 

The cornucopian framework was articulated in the 1980s by economist Julian Simon and military strategist Herman Kahn in an influential book entitled The Resourceful Earth (1984). The book put forward the claim that environmental anxiety—such as that articulated in the influential book The Limits to Growth (1972), the best-selling Population Bomb (1968, referenced by The Washington Post), the work of the Commission on the Year 2000, and, explicitly, the 1980 report to President Jimmy Carter, Global 2000— was misplaced, because human ingenuity can (and, left unimpeded, will) overcome any limits (Barney 1980). Let populations grow alongside markets operating under minimal government constraints, and people will invent solutions to address whatever problems they face. 

The argument was in part an argument for free markets, because it hinged on the idea that people would find solutions, provided they are permitted to— and not unduly fettered by government regulations or social norms. 

Perhaps not surprisingly, these pro-market, anti-Malthusians included anti-environmentalists such as S. Fred Singer, soon to become one of the world’s most prominent climate change deniers, and Aaron Wildavsky, who opposed the precautionary principle and stringent government regulation (even of known harmful products, such as tobacco) on the grounds that they stifle innovation. (Wildavsky served as a founding director of Singer’s Science and Environmental Policy Project and supported TASSC—The Advancement of Sound Science Coalition—a front group for Philip Morris [SourceWatch 2019; Oreskes and Conway 2010]). 

But back to the present. In my 2023 Scientific American piece, I pointed out the illogic of asserting that you could solve the problem of too many people with… more people! Sure, no historian would deny that technological innovation in the nineteenth and twentieth centuries had increased agricultural productivity to the extent that Malthus’s simplistic arithmetic did not hold. Historians are also well aware that Malthus was a reactionary prig who used his “arithmetic” to make a political point as he disparaged the poor laws designed to help the indigent workers displaced and disadvantaged by the growth of industrial capitalism. Caring about the damaging impacts of a crammed world does not a Malthusian make. More to the point, I argued, the cornucopian perspective ignored several important facts. 

First: many of the innovations that increased productivity were not the product of unfettered creativity and certainly not the product of the “invisible hand of the marketplace,” but were the result of active government intervention. The canals and railroads of the nineteenth century, for example—which made it possible to bring foods to markets more easily—relied to a significant extent on government initiative. Big gains in health and life expectancy in the twentieth century—which contributed dramatically to population growth— stemmed from state investment in scientific research and public health. The internet, which has so transformed life of late, was not invented by Al Gore, but it was invented by scientists funded and guided by the US government (Abbate 1999). 

Second: scientists have been warning us about the risks of anthropogenic climate disruption since the 1950s, but technological progress has not stopped the unfolding climate crisis. Creativity, ingenuity, and innovation are real enough, but what they supply does not necessarily match our needs. There’s a Buddhist saying: Technology makes major contributions to the minor needs of men. Thoreau argued that “all our inventions are but improved means to an unimproved end.”

Third, and perhaps most important: the cornucopian conceit (evident in The Washington Post editorial) is that everyone has the chance to develop their ideas and apply their “fresh energy” to solving the world’s problems. Plainly, that is not the case. It’s not enough for people to be born. They have to be born into an environment that offers opportunity. Antoine de Saint-Exupéry made the point with the phrase “Mozart assassiné” in Terre des hommes (1939). It does not suffice for a talented child—even a genius such as Mozart—simply to be born; they must also be born into an environment that nurtures them (as Mozart’s did). With this argument in mind, I wrote: “Most population growth is occurring in poor countries, where most people lack educational opportunities that might enable them to develop the kinds of ideas and skills they would need to apply their ‘fresh energy.’ And, as the biodiversity agreement makes clear, the issue isn’t just living standards as measured by per-capita income. It’s also quality of life, which is threatened by widespread degradation and destruction of nature.”

I concluded the 2023 Scientific American essay by pointing out that while The Washington Post took the fatalistic position that we were lucky that population growth is good, because we can’t do anything about it—“It’s mostly inevitable, anyway,” they shrugged—that is simply not true. It is well established that population growth rates fall when women and girls have access to education. Studies show that opportunities to learn are an effective means to slow population increases. Focusing on that goal—which has many other benefits—most likely will produce the fresh energy and ideas that we need across the globe. It is much more realistic than fatuous assurance that in the future, somehow, all will be well. 

I have always found it bizarre that this point even needs to be made. The evidence is all around us—and has been for some time—that when women are empowered to freely make choices, most of us choose to have two children, or one, or none (Maher et al. 2004; Filipovic 2021). Children are awesome, but they are also an awesome amount of work. Pregnancy and childbirth can be beautiful, but they can also be dangerous and debilitating. Not many women freely choose to give birth ten times. 

It’s also well established that fertility falls as wealth increases. Economics calls this the “demographic-economic paradox.” You might think that wealthier people would have more children, since they can afford them, but the opposite is true. So, one way to slow population growth is through economic development. But as economist Nicolas Stern and others have stressed: climate change—and other aspects of the Anthropocene polycrisis—threatens economic growth (Hileman 2025). So, if you care about population, you really need to care about climate change. 

The Reaction 

Soon after my Scientific American article was pub-lished, two members of the cornucopian Break-through Institute—perhaps not incidentally, both men—attacked me in The Atlantic: Alex Trembath and Vijaya Ramachandran, “The Malthusians Are Back,” March 22, 2023. 

Before I get to their attack, I want to acknow-ledge that many economists—not just blinkered cornucopians and market fundamentalists—are worried about the changing structure of our populations. This is because many of our social-welfare systems depend on young workers for their solvency. The American pay-as-you-go Social Security system is an example. When Social Security was created in the United States in the 1930s, the structure of the US population was a pyramid, with far more working-aged than retired people, so it was no problem for the active workers to pay for the retirees. Today, the population structure is more like a rectangle, leaving far fewer working people available to support the retired folks (US Census Bureau 2020). In Europe, the situation is even worse: the shape is rhomboidal, with a bulge representing the post–World War II baby boom and their children (Eurostat 2025). As this bulge ages and more people live into very old age, the population structure may turn into an inverted pyramid, with fewer working people supporting more retired folks. This is a problem. 

But the Atlantic authors didn’t attack me for being unrealistic about the structure of our social-security system. They accused me of being a scolding Malthusian who hates people. This was, of course, ridiculous, because I said nothing at all to suggest that I dislike people. To the contrary, like most climate scientists and activists, I am concerned with preserving the conditions that make life good for all of us. I am concerned with preventing avoidable human suffering while also preserving the conditions required for nonhuman life. I care about polar bears and people. 

So what is this really about? Why is the idea of limiting population so threatening? I think there are at least two answers to this question. 

The first involves two competing conversations. As I’ve already mentioned, the population structure of wealthy nations is making it more and more difficult to support our social safety nets, particularly in Europe, where those safety nets are generous and the population is not well structured to support them. For many economists, this is an obvious, looming crisis. One solution, of course, is immigration. Since there is no shortage of people in the world—including able-bodied ones—and since many of these people would quite like to come to Europe or the United States (or Japan or South Korea or Australia), the demographic challenge could be solved by increased immigration. 

However, this solution is politically fraught. Immigration has almost certainly played a role in the rise of antidemocratic politics in Germany, France, and the UK. In the United States, President Donald Trump has used immigration as a cudgel to bash his political opponents on all sides, and agents of Immigration and Customs Enforcement have not just beaten immigrants who are in the US illegally, but killed US citizens in the name of immigration enforcement. It won’t do simply to say that wealthy countries can solve their demographic problems with increased immigration from poorer ones. Immigration is too politically complex and divisive to be a simple solution to demographic change. For this reason, some commentators, particularly conservative ones, have argued that wealthy countries need to increase their birth rates and governments should enact pronatalist policies (Brown 2023; Moseley-Morris 2025; Nater 2023). We need more citizens to be born in wealthy countries to take up the demographic slack. 

But there is a totally different conversation taking place among climate scientists, ecologists, and others concerned with the Anthropocene polycrisis. This conversation asserts that population control is essential, for without it, we will soon be looking at the total destruction of biodiversity and potential runaway climate change. 

These two conversations proceed in parallel, in part because the communities involved are different. Climate scientists don’t generally think they need to worry about our social-security systems; economists don’t generally think they need to worry about sea level rise or the alpine snowpack. Each side is right in what it affirms and wrong in what it denies. So The Washington Post can celebrate population growth while the IPBES laments it. 

The second reason has to do with progress. As writer Roy Scranton has argued and I have seconded, the realities and potential demands of the Anthropocene threaten our dominant Western ideals of progress through growth (Oreskes 2024; Scranton 2015 and 2025). At least since the Industrial Revolution, societies in Western Europe and then in North America have imagined a landscape of improved diet, opportunity, health, experience, entertainment, and more through economic growth. For more than two centuries, the citizens of what became the OECD seemed—almost steadily and almost inevitably—to have (and to be able to have) more and more. More calories in our diet. More opportunities to travel and see the world. More years of life. Activities that were once only the province of the very rich became available to the masses. And for the most part, most people saw this as a good thing. They saw this as progress. 

And whether cause, effect, or coincidence, this progress was associated with population growth. Hence, the cornucopians could equate progress with growth and see them as causally related. They could conclude that population growth was not just the outcome of progress, but a cause of it. And if this is true, then population growth is good. And limiting it is not just bad, it is the end of progress. And that’s a tough pill to swallow.