For the past several centuries, we’ve heard about how the world’s population is booming – mostly in the context of how this is an issue for the planet as a whole, much to the ire of some quarters.

Now, though, experts say we’re looking at an imminent decline – though not a sharp one.

Experts say this will occur within the next century and will bring a “revolution in the story of our human civilization.”

They also believe it will cause huge shifts in the way people are living their day-to-day lives.

Right now, there are around 7.8 billion people in the world. That number is still expected to grow over the next few decades before peaking around 2064. From 9.7 billion people, it will fall to 8.8 billion by 2100 (according to this study).

Lead study author Stein Emil Vollset spoke more about their findings.

“The last time that global population declined was in the mid 14th century, due to the Black Plague. If our forecast is correct, it will be the first time population decline is driven by fertility decline, as opposed to events such as a pandemic or famine.”

23 countries could lose more than 50% of their current numbers; Japan, Thailand, Italy, Spain, Portugal, South Korea are counted in this group.

These countries already have an issue with low birth rate and a large aging population.

That said, some parts of the world – North Africa and the Middle East, most notably – would actually see a rise in population.

Sub-Sarharan Africans would triple in number over the course of the next century.

To reach these conclusions, researchers considered mortality, fertility, and migration patterns’ affect on the global population over time. They used data from the Global Burden of Disease Study (2017).

They also tried to account for war, natural disasters, and climate change, though those numbers can be harder to estimate.

They posit that the reasons behind this decline are complex, but are underpinned by the ease of access to contraception and the focus on female empowerment.

“There are two key factors: improvements in access to modern contraception and the education of girls and women. These factors drive the fertility rate – the average number of children a woman delivers over her lifetime which is the largest determinant of population. The global total fertility rate is predicted to steadily decline, from 2.37 in 2017 to 1.66 in 2100, well below the minimum rate (2.1 live births per woman) considered necessary to maintain population numbers.”

Geopolitical shifts are also considered to be a significant factor, along with a dramatic decline in the numbers of working-age adults.

China is estimated to become the largest economy in the world as early as 2035, but the US could overtake that top spot by 2098.

Dr. Richard Horton, the Lancet’s editor-in-chief, explains how many factors are really at play.

“The 21st century will see a revolution in the story of our human civilization. Africa and the Arab World will shape our future, while Europe and Asia will recede in their influence. By the end of the century, the world will be multipolar, with India, Nigeria, China, and the US the dominant powers.”

Because of climate change, migration will have an inevitable impact on the future, regardless of our current trend toward hostile, nationalist rulers.

Basically, Professor Ibrahim Abubakar says we’ll have to reconsider in order to support our population size and ensure economic growth.

“Ultimately, if the new predictions are even half accurate, migration will become a necessity for all nations and not an option. The positive impacts of migration on health and economies are known globally. The choice that we face is whether we improve health and wealth by allowing planned population movement or if we end up with an underclass of imported labour and unstable societies.”

The bottom line seems to be that things are changing, and fairly quickly to boot.

If we want to not only survive but to thrive, we’ll have no choice but to change.

If you think that’s impressive, check out this story about a “goldmine” of lithium that was found in the U.S. that could completely change the EV battery game.