The United Nations Department of Economic & Social Affairs has released its World Population Prospects 2024 report, and a close read shows some interesting and sometimes alarming statistics. The report says that there are currently 8.2 billion people sharing our spaceship Earth, and that is projected, based on recent trends, to go up to around 10.3 billion sometime in the mid-2080s, at which point our overall population will start gradually declining.

This population decline will be experienced very differently in different countries. The report notes that 24 countries have already seen a peak population level, and will experience fewer citizens in the future than they have now. The list, unsurprisingly, includes China and Japan, but also South Korea, Spain, Italy, Germany, Greece, Portugal, Hungary, Austria and Poland. China, for example, is projected to lose more than half of its current population by 2100. The Japanese population is projected to drop from roughly 125 million today to somewhere close to 80 million by the end of the century.

Another 48 countries, representing 10% of the world’s current population, will experience population peaks sometime between now and 2054. The countries that are projected to continue growing their population includes the United States, India, Indonesia, Nigeria and Pakistan.

The report also says that the world is aging. Sometime in the late 2070s, the number of persons age 65 or older globally will be higher than the number of children under age 18. The report cites declining birthrates and increasing lifespans overall, and notes that the current global fertility rate is 2.25 live births per woman, incrementally above the 2.1 level that would essentially lead to a static population. Meanwhile, average longevity is currently 73.3 years across the world, and is projected to reach 77.4 years by 2054.

Once again, there are dramatic differences. Korea, Italy and Spain are experiencing fewer than 1.4 births per female citizen; in Korea, that figure is now down to 0.75. China’s average and projected lifespan is roughly comparable with the world’s, while Koreans are living, on average, well into their 80s.

All of this points to a very different world than we see today. One of the biggest drivers of economic growth in a country (and the world) is population growth: the growing number of workers and consumers. In the future, we may have to give up the idea that our individual and global economies have to grow for us to be prosperous. And when over-65 citizens outnumber working-age citizens, there will be more pressure on the workers to somehow economically support a growing number of (potentially) non-contributors to the economy.

The report talks about encouraging more women to give birth, more people of advanced age to continue working, and social programs that address aging demographics. But the truth is that the world is sailing into uncharted territory, as our population declines for the first time since people emerged from the caves. Nobody really know how that will play out.