When the global population passed the 8 billion mark on Nov. 15 last year, demographers had a peak in sight: 10.4 billion, around the year 2080.
But a report published on Monday (March 27) by Earth4All, a collective that includes the Potsdam Institute for Climate Impact Research and the Stockholm Resilience Centre, found that the world’s population growth may peak lower and begin to drop sooner than previous projections.
In the most optimistic scenario, the report found that population growth could peak at 8.5 billion in 2040, and drop below 6 billion by 2100. This reduction would require deep investments in poverty alleviation, of a kind that would eliminate extreme poverty by 2060, with investments in education and health and “extraordinary policy turnarounds on food and energy security, inequality and gender equity,” the report’s authors wrote.
If that doesn’t happen and economic development continues at the current pace, the report still finds that population growth could peak at 8.6 billion in 2050, and fall below 8 billion by 2100. This is a considerably sharper fall than UN projections, which estimate a population of 8.5 billion in 2030, 9.7 billion by 2050, and a peak of around 10.4 billion people during the 2080s, where it will plateau until 2100.
The link between population and its effect on the planet has long been fraught, causing consternation at least since 1968, when a highly debated, fear-mongering book called The Population Bomb was published. More recent debates explore the morality of having children, given the pressures that a surging population places on the world and its changing climate.
But if Earth4All’s best scenario plays out, the so-called population bomb may never go off. To arrive at its forecasts, Earth4All’s researchers used a methodology (pdf) that takes into account economic advancement and change through the decades, rather than the UN’s statistical projection, which assumes that the conditions shaping today’s fertility rates will hold until 2050 and 2100.
Education and economic progress have reliably reduced fertility rates in the past, the report argues. As economic conditions improve for more women, especially in the developing countries with the highest fertility rates, they will have fewer children and lead to a quicker decline in global population.
While a growing population will certainly use more resources, the relationship between fertility and emissions is not a direct one. Take, for example, Somalia which has among the highest fertility rates in the world, at 6.4 births per woman. Its emissions per capita is so low, it is statistically zero, according to World Bank data. South Korea, which has the world’s lowest fertility rate at 0.8, emits 11.8 metric tons of CO2 per capita. The US, with a fertility rate of 1.8, produces 14.7 metric tons of CO2 per capita. (Not incidentally, Somalia suffers some of the worst effects of climate change caused by other nations.)
Wealthy countries have significantly higher emissions per person than developing ones. This raises a fundamental paradox in the report’s findings: the projected fall in fertility rates is predicated on improved economic access, which in turn will raise the carbon footprints of children born in the next few decades.
For Beniamino Callegari, one of the authors of the Earth4All report, this is exactly the point. “Even if we predict a lower peak in population and then a decline,” Cellegari told Quartz, “we still see that there is a need for significant global efforts to fight climate change. In itself, this population decline is not sufficient.”
A lower population can ease pressure on the climate transition and make it cheaper, but “we still have to address the issue with significant global policy efforts,” Callegari said. The world will still need to move away from using fossil fuels and change the way it consumes and produces goods, buildings, vehicles, food, and everything else that makes up our current economy. “Otherwise, we will have unsustainable climate change. We will be living outside the planetary boundaries and things are only going to get worse for us.”