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By Marni Rose McFall
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Scientists have mapped out a scenario of a global population crisis by the year 2064.
The research by Alessio Zaccone and the late Kostya Trachenko, published in the journal Chaos, Solitons & Fractals, uses a simple math equation to show how the world’s population has grown over the last 12,000 years. The model is then used to explore future possible scenarios.
One such scenario is that if Earth had an abrupt limit on how many people it can support, the global population could halve as early as 2064.
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“Global population growth may be more sensitive to environmental and societal pressures than many traditional population models assumed,” Zaccone told Newsweek by email. “The study is not meant to predict the future with certainty, but rather to explore how human populations might respond under different stress scenarios.”
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Why It Matters
Around the globe, experts share a common concern: population decline. The United Nations has estimated that the world’s population will peak at 10.3 billion by 2080, then enter a slow descent.
Birth rates are declining below the level needed to maintain a stable population. Low birth rates can result in an aging population and is believed to correlate with economic challenges, placing greater strain on the healthcare system.
What the Study Shows
The study found that a single nonlinear equation—originally used in physics—can explain almost every major pattern in global population growth since the Neolithic era.
It outlines a possible scenario in which a crisis would halve a population by 2064, stating that if a major global shock, like disease or war, imposed a strict carrying capacity, the model predicts that the population could peak and, in a worst-case scenario, fall by half by 2064.
“Global population dynamics may be much more nonlinear, and therefore potentially more sensitive and unstable, than previously thought,” Zaccone said. “Relatively small changes in the parameters entering the equation can lead to dramatically different scenarios. Models like this are useful because they provide relatively simple but mathematically powerful frameworks for studying long-term population dynamics and feedback effects between humanity and the environment.
“The mathematical equation we used was not originally developed for demography at all, but emerged from previous studies of relaxation processes in glasses and disordered materials in condensed matter physics.”
Which Countries Are Experiencing Population Decline?
Multiple countries are experiencing a population decline.
America’s total fertility has plummeted to a historic low of 1.6 children per woman, below the 2.1 replacement level needed to maintain population, according to the U.S. Centers for Disease Control and Prevention, as of 2023.
Fertility in the U.S. dropped further in 2025, with 3,606,400 births recorded, according to the CDC, a 1 percent decrease from the previous year. The general fertility rate fell to 53.1 births for every 1,000 females ages 15 to 44.
At the start of 2025, the Trump administration passed a number of policies aimed at boosting birth rates. This included an executive order expanding access to in vitro fertilization (IVF) and a Department of Transportation directive to give precedence to "communities with marriage and birth rates higher than the national average."
China is also experiencing a population and birthrate decline. In 2025, the decline continued for the fourth consecutive year, with 7.92 million registered births, down 17 percent from 9.54 million in 2024 and the lowest since records began in 1949.
Beijing has moved to boost the birth rate, allocating $12.953 billion for its first nationwide childcare subsidy program. Beyond that, there are plans to expand national healthcare insurance to cover childbirth-related expenses, including IVF.
In 2025, Russia’s birth rate hit a historic low, falling to levels not seen since the late 18th to early 19th century. Russia has faced a plunging birth rate and population decline for decades, and the issue has been a key concern of President Vladimir Putin, but the problem has only worsened amid the war with Ukraine that began in February 2022, from high casualty rates to men fleeing the country to avoid being conscripted to fight.
Russia is now referring women who don’t want children to psychologists to try to address the dwindling birth rate.
According to the World Population Prospects, the global fertility rate stands at 2.25 live births per woman, one child fewer than a generation ago. The figure is projected to decline to 2.1 by the late 2040s.
Which Countries Are Experiencing a Population Boom?
Sub-Saharan Africa is poised for a population boom.
Data from the United Nations shows that countries including Niger, Democratic Republic of Congo, Somalia, Chad and Angola are among the fastest-growing nations. Many of these countries have fertility rates of above five children per woman and populations in which a large share of citizens are under age 25.
The United Nations projects that sub-Saharan Africa’s population could increase by nearly 80 percent by 2054, reaching around 2.2 billion people.
The United Nations also predicts that Niger and the Democratic Republic of Congo could double in size within a few decades.
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