Cities are dynamic, not static grids, and urbanization is a “spiky,” cyclical, and asynchronous process.
People often speak metaphorically of the heartbeat or pulse of a city, but according to the authors of a new paper published in the Proceedings of the National Academy of Sciences, cities do indeed have an “urban pulse”—an indication of urban “metabolic activity” that can be measured to suss out telltale patterns. And those patterns could help inform future public policy around urban planning.
The precise definition of urbanization has shifted over the centuries. Zhe Zhu of the University of Connecticut and his fellow authors adopted a broad version for their study. It features fundamental “processes of concurrent change in at least six dimensions, including demography, economy, infrastructure, environment, governance and culture,” they wrote. “Together they give rise to outcomes, measurable results of the process, such as population growth, urban land expansion, GDP growth, and innovation.” Their chosen metrics reflect this dynamic view: Cities are not static grids but “living, adaptive ecosystems.”
“For decades, we had just been capturing the outcome of urbanization—a house that’s been built, or a road expansion,” said Zhu. “But you don’t really see the dynamics within an urban area. This is going to be a very impactful tool influencing not only top-down policy decisions from governments but also bottom-up decisions from everyday people navigating their cities.” One day we may be able to check a neighborhood’s “urban pulse” while house-hunting, for instance, or while scouting potential locations for a new business.
Thanks to advances in remote sensing and various analytical methods, it’s possible to gather multidimensional data from a variety of sources, such as satellite imagery, or geolocated mobile or social media data. Zhu et al. got their data from the NASA Harmonized Landsat and Sentinel-2 databases to analyze new construction, repairs, improvements to infrastructure, green space expansions, and demolitions in six different cities: Seattle, Shenzhen, Lagos, Mumbai, Dubai, and Mexico City.
Their analysis revealed three distinctive “vital signs” for monitoring cities. First, urbanization is “spiky”: There are sharp, short-lived spikes in activity, not smooth continuous growth. The best example of this, per the authors, is Dubai, whose coastal areas showed very large spikes in redevelopment activity—most notably capital-intensive projects like luxury towers or mixed-used buildings. Shenzhen’s spikes, by contrast, were more clustered, “reflecting the city’s capacity for rapid, state-led mobilization of capital and construction,” they wrote.
Second, urbanization is cyclical and non periodic: There are distinct phases of building/expansion, a peak and stabilization, followed by relative decline or dormancy. And no two cities are exactly alike. The patterns for specific cities aren’t predictable like temporal seasons, reflecting instead unique elements of each. Lagos, for instance, has fragmented and uneven cycles, with some neighborhoods showing lulls lasting many years punctuated by occasional periods of heightened activity. Dubai has highly irregular, more frequent cycles of expansion and contraction.
Finally, urbanization is asynchronous: Even within cities there is substantial variance among neighborhoods. The process does not occur at coordinated rates or times, with each neighborhood exhibiting its own rhythm. Just because there is a major spike in activity in Dubai’s Al Mamzar region, that doesn’t mean the same thing is happening in Al Jaddaf or Mirdif.
One notable exception is the synchronized dip in activity during the COVID-19 pandemic, which caused shutdowns all around the world—a phenomenon the authors likened to cardiac arrest. Even then, there were significant differences in patterns among cities (and intra-city neighborhoods) in terms of how cities recovered from the shutdowns. “It’s like in human beings,” said Zhu. “When you get a disease, it’s not going to show up exactly the same in different people.”
“Collectively, these results suggest that urbanization is a mosaic process, produced through overlapping but uncoordinated pulses of activity that vary across space and time,” the authors concluded. And while heart-related arrhythmia is bad for one’s health, they think that this “urban arrhythmia” is a sign of resilience in cities. “By decoupling development cycles, cities avoid the overheating, labor shortages, and infrastructure collapse associated with total synchronization,” they wrote. “The lack of coordination may not be a failure of planning, but an adaptive mechanism that distributes urban stress over time.”
DOI: PNAS, 2026. 10.1073/pnas.2537770123 (About DOIs).
Source: Ars Technica
