Cities are soaring upward at a greater rate than they are spreading out—reshaping resource use, the environment, and urban life, according to a new study.
Researchers from the University of New Hampshire used satellite data from the 1990s to the 2010s for over 1,550 cities, measuring the footprint and height of buildings. The study found that while cities once expanded by covering more land, they are now increasingly building upward, with Asian cities leading this charge.
The authors tracked how cities grow by first mapping their sprawl over time from space, but also by bouncing microwaves from satellites off the urban centers to map their growth in three dimensions. The move toward taller buildings rather than wider sprawl could have a significant impact on urban living conditions, the study authors note.
David Wilson, a professor of geography at the University of Illinois Urbana-Champaign, describes the study as "extremely interesting" and says that the shift from horizontal to vertical urban growth offers benefits and challenges.
"This trend is very positive for promoting sustainability and resource management. Less blocks, neighbourhoods, and communities will require the hand of government to reach out and expend scarce resources for policing, fire protection, and provision of housing services," he told Newsweek via email.
He added: "At the same time, the prognosis for fostering equity in the city is grim. Dramatic increases in vertical development, especially in mega-cities, often signal the realities of downtown gentrification kicking into hyperdrive, a notorious process for displacing and further isolating the poor and the stigmatized."
Specifically, larger cities with populations over 10 million are at the forefront of this vertical transition.
In China, urban expansion has undergone a dramatic transformation over recent decades. Initially marked by wide outward growth, the trend has now shifted toward vertical development, with taller buildings increasingly replacing shorter ones.
Cities like Beijing and Shanghai have seen a significant slowdown in outward expansion, while vertical growth has surged, making China home to some of the most pronounced examples of rapid growth in both horizontal and vertical dimensions.
However, Europe has shown minimal change in urban growth patterns, with a persistent dominance of outward growth and only a modest increase in vertical development.
In Africa, South Africa has seen a significant slowdown in overall growth, while West Africa is shifting from outward expansion to upward development.
Overall, rapid upward growth was uncommon in the 1990s, but became significantly more frequent by the 2010s. In contrast, rapid outward growth decreased during this period.
According to the researchers, this shift from low-rise to high-rise buildings mirrors broader economic changes, especially in larger cities. It indicates a global trend toward denser and taller urban environments, driven by factors such as increasing land prices and economic development.
While high-rise buildings can save land and improve walkability, they also pose challenges like higher embodied carbon and energy needs, the study's authors note. The researchers suggest their findings could enhance our understanding of urbanization, which is significantly reshaping Earth's surface.
The full findings of the study are published in the journal Nature Cities.
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