One of the biggest issues of the 21st century, yet to capture widespread attention, is rapidly changing expert projections of the global population over the coming decades. Not so long ago, conventional wisdom held that the world was headed for an overpopulation crisis marked by resource shortages and addressable only through strict population controls.
But the world may soon face the opposite problem: potentially rapid declines in fertility leading to peak global population much sooner than even recent projections anticipated, and in some extreme scenarios, a global population collapse. Today, I take a look at what such emerging views on global population might mean for global energy supply and demand and offer three (perhaps provocative) perspectives.
A smaller population does not necessarily mean less energy consumption.
One way to get a glimpse of the future is to look at places where it may already have arrived. Japan is one such place, having experienced a gradual population decline since 2010. Over that same period, Japan also experienced a corresponding drop in both overall energy consumption and energy consumption per capita.
The number of other large countries that have experienced demographically-driven population declines over more than a decade—including Russia, Poland, Romania—is very small, and to date there are no examples of countries that have experienced a population decline and an increase in per capita energy consumption. However, it is not difficult to envision how such a combination might occur.
Consider India, which the United Nations currently projects will see peak population in the early 2060s. As the world’s most populous country, India remains well below average in both per capita GDP and per capita energy consumption. Within India, estimates (here and here) suggest that about 10 percent of the population—about 160 million people, roughly the same as the populations of France, Germany, and the Netherlands combined—lives at per capita GDP and energy consumption levels above the global average.
That leaves more than 1.3 billion Indians, or roughly three times the total population of the European Union’s 27 member states, living below the global income and energy consumption averages. India thus includes the equivalent of three advanced economies, along with 81 countries that have yet to reach advanced levels of income and energy consumption. In such circumstances, we can be certain that individuals, communities, businesses, and governments will continue to enact policies that foster economic growth and correspondingly increased energy consumption, regardless of overall demographic trends.
India is not alone. Pakistan, Bangladesh, Nigeria, Ethiopia, and other developing countries, with a combined population totaling more than 2.5 billion, will continue to seek consistent growth in the coming decades, meaning greater energy consumption overall regardless of trends in population and other factors.
Even with a declining population, the world will have more wealthy people.
Even as total global population peaks and declines, the overall number of wealthy people on the planet is almost certain to continue to increase. While overall economic growth may slow from the rates seen in the 20th century, per capita wealth is likely to continue to increase.
Some economists have suggested that the 21st century might see slower economic growth than previously anticipated. For instance, Charles I. Jones of Stanford University argues that a world with fewer people would have fewer innovative ideas and fewer opportunities to invest in growth, contributing to a “long list of headwinds [that] confront future economic growth, suggesting that growth in the next several decades could be slower than in the past half century.”
Similarly, Matthew G. Burgess and his colleagues foresee challenges facing future global economic growth, but even so, predict increasing overall global wealth. “Despite these potential challenges, we note that the world envisioned … is nonetheless substantially richer than the world today—with many regions reaching affluence greater than today’s affluence in high-income regions, and with lower-income regions having the most rapid increases in affluence,” they wrote in a 2023 article for Nature Communications Earth & Environment.
While there has been much discussion of the implications of artificial intelligence and computing demands for future energy demand, several more prosaic technologies are all but certain to drive increasing future energy demand.
One is the increased demand for cooling. According to the International Energy Agency, the number of air conditioning units worldwide is projected to more than double over the next 25 years. A warming planet will only create more demand for cooling. As the world gets richer, we can be certain that such demand will be met.
Similarly, global air travel is expected to more than double by 2050 as the world becomes wealthier, according to projections by the Airports Council International.
Regardless of the exact date of the world’s population peak, it is inevitable that the proportion and overall number of wealthy people will increase as far as the eye can see, leading to greater demand for modern energy services like air conditioning and air travel.
Fewer people could mitigate climate change concerns.
One of the key factors in projections of future carbon dioxide emissions is the global population. More people, all else equal, means more emissions. More emissions mean greater increases in global temperatures and thus greater climate change.
The scenarios on which climate science and policy rely are obsolete, and embedded within their assumptions are long-outdated perspectives on future population growth. Consider that the most commonly used scenario in climate research over the past decade foresees the global population hitting 12 billion in 2100 and continuing to rise. This stands in stark contrast to the United Nations’ expectations of a peak population of about 10 billion by mid-2080, followed by a decline. Other researchers suggest a peak of about 9 billion occurring around midcentury.
Regardless of the exact details, we can have some confidence that climate scenarios are well out of date, given their reliance on population projections far above the current consensus.
I recently conducted an analysis in which I simply substituted updated population and corresponding GDP growth assumptions into projections for the climate scenario known as SSP2-4.5, which is commonly used by the World Climate Research Programme. That scenario is consistent with projections of future global temperature change associated with “current policies” (i.e., where we think the world is headed based on policies in place today).
Long story short: Adopting updated assumptions of population and economic growth suggests a much lower amount of global temperature increase to 2100.
Of course, not all else is equal in scenarios and projections. However, fewer people and lower levels of aggregate global economic growth would imply reduced projections of climate change, based on lower emissions of carbon dioxide from fossil fuels. Exactly how much projections might change will await the climate research community catching up to current understandings in their scenarios used in research.
One thing is certain, however: Evolving perspectives on population will lead to moderating views on future climate change. That doesn’t mean the challenges of human-driven climate change will go away, but changing perspectives on population dynamics contribute to the growing understanding that climate change is a circumstance to be managed—and not the end of the world.
Policy Watch
- The Environmental Protection Agency revoked the so-called “endangerment finding,” a 2009 determination that greenhouse gases threaten public health and the basis for many of the agency’s regulations. Announcing the decision, EPA head Lee Zeldin hailed it as “the largest act of deregulation in the history of the United States.” Both the New York Times and Wall Street Journal have suggested that the action represents a major policy shift. I’m not so certain, as there is little evidence that any administration has acted in a way that has resulted in accelerating or slowing decarbonization in the U.S. economy.
- In Japan, one of the nuclear power generators at the Kashiwazaki-Kariwa nuclear facility restarted and started delivering electricity. The restart marks the 15th plant to be brought back online after all 54 of Japan’s nuclear power plants were shut down following the Fukushima accident in 2011. The restart also heralds a resurgence of support for nuclear power in Japan. The landslide victory in Japan’s elections earlier this week of Prime Minister Sanae Takaichi and her Liberal Democratic Party indicates that Japanese nuclear power will continue to enjoy broad political support.
Innovation Spotlight
- PowerLines, a nonprofit focused on electricity, issued a report suggesting that concerns about affordability are not going away anytime soon: “PowerLines’ year-end analysis finds that electric and gas utilities requested nearly $31 billion in rate increases in 2025, more than double the $15 billion in rate increases requested in 2024. These rate increase requests will affect the utility bills of 81 million Americans, contributing to rising financial anxiety for American consumers at a time when cost-of-living concerns are top of mind.” The race between growing demand and new supply will put U.S. innovation policies to the test.
Further Reading
- The Journal of Economic Perspectives recently published a new collection of papers on birth rates, detailing a consistent trend of decline in recent decades. “Fertility is low or falling across the world: among high-, middle-, and low-income countries; among secular and religious populations; and in economies where the state is large and where it is small. Birth rates have been falling not only for decades, but for centuries,” Michael Geruso and Dean Spears, researchers at the University of Texas at Austin, wrote in one of the articles. “They have been falling for as long as there are good historical records to document them. Occasional bumps—even big ones like the mid-twentieth-century Baby Boom—have been temporary variations around this long-term global trend.”
- Relatedly, writing for the Economics Observatory, Federica Coelli and Pablo García Guzmán asked: How could falling birth rates reshape the global economy? “More than two-thirds of humanity now live in countries where fertility has fallen below the level needed for a stable population. This fundamental demographic shift is transforming economies, raising questions about ageing populations, shrinking workforces and the sustainability of welfare states.”