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This series—featuring scholars from the Futures Lab, the International Security Program, and across CSIS—explores emerging challenges and opportunities that NATO is likely to confront after its 75th anniversary.
In the future, global aging will require NATO to reassess operational readiness, recruitment, and resilience through the deployment of innovative policies that account for shrinking workforces and aging populations at home and new population centers abroad.
This month’s 2024 NATO summit in Washington comes at a time of significant demographic transition for its member nations and the world, requiring a fresh look at how the alliance can ensure force readiness in an era of global aging. Demographic change, often measured in years, decades, and even generations, tends to be overlooked by national security analysts focused on immediate military threats and geopolitical developments. Although demographics can seem like a slow-moving phenomenon—much like Hemingway’s description of a man going bankrupt, “gradually, then suddenly”—its impacts can manifest abruptly and pose significant disruption without proper planning. Increasingly, policymakers are coming to grips with a trend that is often overshadowed by the explosive population growth that has defined much of the last century: the world’s population is aging. Preparing for an older global population requires strategic investments today. As NATO navigates the complexities of a rapidly evolving security landscape, the implications of global aging will be a critical factor shaping the alliance’s future strategies and posture.
Over the past seven decades, the global population has surged from 2.5 billion to 8.1 billion. However, total fertility rates (TFRs)—the average number of children a woman has in her lifetime—have declined during this period, tempering the future growth trajectory. The United Nations projects that human population growth will slow and eventually peak at around 10.4 billion by the mid-2080s. A 2020 study published in The Lancet projects that the world population could peak as soon as 2064 at 9.7 billion people. Population change is not evenly distributed across geographies. There is a strong negative correlation between TFR and GDP per capita. Advanced economies tend to have TFRs well below the standard replacement rate of 2.1 children per woman. As a result, much of the population growth in the future will take place in the Global South, where TFRs remain higher. This will reshape the geopolitical landscape, as countries in regions like Africa, the Middle East, and South Asia try to capitalize on their growing populations and advanced economies grapple with shrinking, aging workforces.
Although declining TFRs are a near universal trend, NATO member countries are further along in this demographic transition. As of 2023, every NATO member country had a fertility rate below replacement rate. Spain has the lowest TFR among NATO members at 1.29 children per woman. Even Türkiye, which boasts NATO’s highest TFR, is below replacement rate at 1.86 children per woman. In 2023, through a combination of low fertility and high emigration rates, over half of all NATO member countries experienced negative population growth. This means that in the absence of immigration, populations will steadily shrink in the coming decades.
Over the past 70 years, global life expectancy has also risen dramatically, from 50 years in 1960 to 71 years in 2023. As longevity increases and fertility rates fall, societies are aging. NATO’s oldest member country, Italy, has a median age of over 46 years. This trend is accelerating, and by 2050, two-thirds of all NATO countries will surpass this benchmark, with the remaining one-third aging rapidly. Türkiye, currently NATO’s youngest society, with a median age of 31.8 years, will see this rise to 41.1 years by 2050.
Falling fertility rates and the shift toward older populations combine to produce a riddle for defense planning. Fewer young people today means fewer recruits tomorrow. Today, 55 percent of NATO international staff are 46 or older, and as member nations continue to age, this percentage can be expected to grow. For government planners, a shrinking, aging workforce threatens to slow economic growth and strain national budgets. Policy responses such as enhanced recruitment and retention strategies or increased investments in the use of automation, artificial intelligence, and advanced technologies can help maintain operational readiness, but they are expensive. Meanwhile, health care and pension costs will continue to increase as populations age and live longer, potentially reducing the financial resources available for defense spending. Although each NATO country is at a different stage in its demographic transition and NATO countries range widely in their budget planning, the Organisation for Economic Co-operation and Development projects that pension expenditures will rise by a median 2.5 percent of GDP among its NATO members. Demographic shifts also alter public opinion and governmental budget priorities, making necessary budgetary reforms hard to implement. France, for example, saw widespread protests in response to planned reforms to increase the retirement age from 62 to 64.
With proper planning, global aging offers opportunities for policymakers and security leaders to reassess and redefine operational readiness, recruitment, and resilience. Global aging will drive innovation in technological fields like robotics, automation, and education that will help older service members extend their time in uniform. Advanced battlefield technologies can help maintain robust defense capabilities and tend to require more technical training than physical training. Providing upskilling could create opportunities to retain current service members while expanding the recruitment pool as the median age ticks up. As societies age, governments can also do more to invest in preventative health care policies to ensure their aging populations live longer, healthier lives, extend their productive working years, reduce burdensome health care costs associated with chronic diseases, and ensure balanced spending priorities between public welfare and national defense. Lastly, robust immigration policies can help attract global talent, offset shrinking workforces, and boost economic productivity. Over the long term, increases in immigration tend to contribute to economic growth at greater rates than if migration had not occurred.
Understanding and addressing the implications of demographic change is essential for ensuring NATO’s continued effectiveness and resilience. In the future, NATO member countries will be older. However, if NATO planners prepare the groundwork now to navigate the demographic transition, NATO can emerge stronger and wiser.
Eric Palomaa is director of the Hess Center for New Frontiers at the Center for Strategic and International Studies in Washington, D.C.
