I hadn’t been paying close attention to the Day of 8 Billion. Milestones make good headlines, but concentrating on a few big numbers can obscure more revealing trends that really explain how the world has changed since there were just 7 billion of us. Here are two examples. The proportion of people living in extreme poverty has steadily declined over the past decade. (In 2010, 16.3 percent of the world lived on less than $2.15 a day, while today only 9 percent of people live on such a paltry amount.) And in India and China—which contributed the most new births in the past decade—GDP per capita and life expectancy have risen even while populations boomed. To put it simply, more people are living better lives today than at almost any other point in human history. As the Day of 8 Billion rolled around, my inbox filled with a steady drip of press releases warning that the milestone represented a planetary crisis point. I have a hunch as to why I was getting these stories sent my way. A couple of months earlier, I’d written an article about why Elon Musk is wrong to worry about falling populations. In the near term, demographers pointed out to me, the world’s population is only heading upward. Managing that increase is the real challenge facing the planet right now. In the eyes of NGO press officers and certain angry people on Twitter, this put me firmly in the camp of “journalists who are convinced that we should be less afraid of talking about ‘overpopulation’ and its effect on the environment.” A lot of online coverage about the Day of 8 Billion came from the same perspective. “It should not be controversial to say a population of 8 billion will have a grave impact on the climate,” read one headline in The Guardian. On a basic level, that’s completely true. If everything else stays the same, more people on the planet will mean higher carbon emissions. The climate solutions charity Project Drawdown estimates that providing better family planning and education will help avoid 68.9 billion metric tons of CO2 emissions by 2050—roughly equivalent to two years of emissions from fossil fuels and industry. We need to tread carefully when we talk about population and climate change. It’s easy to look at a world of 8 billion and conclude that there are “too many” people on the planet. But who do we really mean when we talk about overpopulation? Someone living in the United States is responsible for about 15 metric tons of CO2 emissions per year. But in the eight countries where the majority of population growth by the year 2050 will be concentrated, per capita emissions are just a fraction of US levels. In the Democratic Republic of Congo (DRC), which is projected to grow by more than 120 million in the next 20 years, each person produces just 30 kilograms of CO2 each year. Emissions are a consequence of consumption, not just population. The world’s richest people are the biggest emitters. One study from the World Inequality Lab found that as emissions have fallen for the middle class in rich countries, those from the top 0.001 percent have risen by 107 percent. “When I see rich people with massive families I think, no, we don’t have the capacity to have more rich people on the planet,” says Lorraine Whitmarsh, a psychologist at the University of Bath who studies behavior and climate change. If we really want to reduce emissions, then starting with reducing consumption in the developed world, where populations are stagnant, makes the most sense. Giving women access to good education and voluntary family planning is the right thing to do, because it means more people enjoy better lives. In the DRC, women who are educated past secondary level have about three children on average, compared with more than seven children from women who don’t have the same education. “I want to live in a world where we have fundamental freedoms and human rights,” says Kimberly Nicholas, a climate scientist at Lund University in Sweden. “We developed that system only quite recently and under a period of climate stability. We don’t have any evidence that it’s possible to have that kind of world under continually worsening climate breakdown.” The future of our planet is about way more than the sheer number of humans living here. It’s about whether they will have good lives and live in places with stable governments, access to health care, and basic human rights. “Thinking of a population as a faceless crowd or mass—you really don’t think about people’s identities or humanity in that context,” says Nicholas. “Part of the challenge of solving the climate crisis is trying to expand our sphere of empathy beyond just the immediate circle of our closest family and friends.” In 2017, Nicholas published a study looking at the effect that changes in lifestyle had on carbon emissions. By a long shot, the highest-impact decision someone could make was to choose to have one fewer child. Nicholas regularly gets emails from people who ask her whether they should feel guilty about wanting to have another child. Ultimately, Nicholas would prefer we live in a world where everyone can satisfy their own preferences without worrying about the effect it has on the planet. “The decision whether—and if—to have children is a fundamental human right and needs to be upheld and protected,” she says. Whether there are 8 billion humans or 10 billion, we should be thinking about how to find ways for everyone to live good lives. “We have this carbon budget to prevent catastrophic climate change,” says Nicholas, referring to the goals of the Paris Climate agreement. “It’s very quickly running out.” Earth has the capacity for more people or for fewer people—it all depends on what those of us who are alive right now are prepared to do to make sure we don’t wreck the place before the next billion get here.
