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Are you interested how urban form has been influenced by globalisation?
Our debate today works with the article titled The global homogenization of urban form – An assessment of 194 cities from 2020, by Richard Lemoine-Rodríguez, Luis Inostroza, and Harald Zepp, published in the Landscape and Urban Planning journal.
This is a great preparation to our next interview with Alex Josephson in episode 406 talking about the globalisation of architecture.
Since we are investigating the future of cities, I thought it would be interesting to see the effect of globalisation on the built environment. This article shows most of cities becoming more homogenous and transitional as a consequence of fragmentation and compactness.
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Welcome to today’s What is The Future For Cities podcast and its Research episode; my name is Fanni, and today we will introduce a research by summarising it. The episode really is just a short summary of the original investigation, and, in case it is interesting enough, I would encourage everyone to check out the whole documentation. This conversation was produced and generated with Notebook LM as two hosts dissecting the whole research.
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Speaker 1: Today we are looking at the literal shape of human civilization. We’re analyzing a massive piece of research by Lemoine Rodriguez and colleagues, which tracked the evolution of 194 cities across the globe over a 25 year period.
Speaker 2: And honestly, the picture it paints is it’s unsettling. We’re watching the distinctiveness of our world just vanish in real time.
Speaker 1: Now, see, that’s the pessimist. Read the study identifies this phenomenon called the Global Homogenization of Urban Form. The data shows that whether a city is in Asia or Latin America or Africa, it’s physically converging toward a single unified spatial shape. I look at this data and I see a powerful underlying law of co-evolution. It suggests urbanism operates as a coherent global system, almost like a biological organism, finding its optimal form,
Speaker 2: and I look at the exact same data and I see a failure of imagination. I see a global homogenization that’s essentially a flattening of local culture and more importantly, ecology. We’re seeing a convergence, sure, but it looks less like an evolution toward perfection and more like a regression towards some standardized, mediocre mean. We’re just bulldozing local context in favour of a geometry that doesn’t actually fit anywhere.
Speaker 1: I see why you might feel that way. You know about the aesthetics, but we need to talk about the mechanics. If we can identify a universal trajectory for how cities grow, we move from chaos to predictability. And in a world where urban populations are absolutely exploding, predictability is the only way we manage resources
Speaker 2: or it’s the way we lock in a mistake at a planetary scale. But before we argue about the consequences, we should probably help the listeners visualize what the study actually found, because when we say homogenization, it sounds so abstract. The reality on the ground is concrete, literally
Speaker 1: agreed. Let’s get into the evidence. So the globalization and convergence perspective, my perspective, it relies on the data found in this study. The researchers used satellite imagery and landscape metrics to categorize cities into four very distinct types. You have the compact gray, the fragmented complex, the ragged small, and the transitional.
Speaker 2: Let’s actually paint a picture of these because the names are a bit academic. When the study talks about compact gray, they aren’t just talking about density, they’re talking about cities often in the Middle East or parts of Asia where the concrete is just continuous. It’s a solid block of gray on a satellite map. Very few parks, very few breaks in the urban fabric. It’s efficient, but it is intense.
Speaker 1: You contrast that with the fragmented complex cluster. This is your classic American sprawl, thank Houston or Atlanta. You have leapfrog development patches of housing separated by unused land highways, cutting through everything. It’s a very high entropy, complex shape,
Speaker 2: and then you have ragged small. Think of this like an ink blot maybe, or a starburst. These are usually smaller cities in developing regions. They have these fingers of urbanization reaching out into the countryside with farm fields or forests, wedge deep between the buildings. It’s messy, but it’s permeable. The air can actually flow through it.
Speaker 1: Exactly. And finally, the transitional, this is the middle ground. It’s not as dense as the compact gray, but it’s not as scattered as the fragmented complex. And here is the smoking gun for my argument. In 1990, the cities in this study were fairly evenly distributed across those four types. The world was diverse. You could almost tell where a city was just by looking at its shape.
Speaker 2: And by 2015,
Speaker 1: by 2015, the sample is overwhelmingly dominated by just one type, the transitional cluster. We went from this balanced spread to having 98 out of 194 cities, more than half sitting in this transitional middle ground. The extremes are dying out. The ragged small ink blots are filling in their gaps. The compact gray blocks are expanding outward. The world is moving toward an equilibrium,
Speaker 2: which basically just means the world is becoming average.
Speaker 1: It means they’re converging. This isn’t random chance the authors invokes Z’s Law and Urban Scaling theory, which is, it’s fascinating. Essentially, it suggests cities aren’t just piles of bricks. They act like biological organisms. As a mouse grows into an elephant, its metabolism slows down and its shape changes in a predictable ratio to support that mass. The data suggests cities do the same as they metabolize energy in people. They are, in a way mathematically forced into this transitional structure to remain efficient. It’s not a choice, it’s physics.
Speaker 2: I’m sorry, but I just don’t buy that. It’s physics. You see a self-organizing system. I see a contagion of bad planning. If this were truly a universal law of physics, it would apply to everyone equally, but it doesn’t, and this is where your argument cracks.
Speaker 1: You are referring to the outliers
Speaker 2: I’m referring to, the land rich developed countries. The study highlights this beautifully. The USA Australia and New Zealand, cities like Houston, Auckland, Perth, they are not converging. They remain stubbornly fragmented, complex from 1990 to 2015. They’re the most sprawled land hungry cities on earth, and they haven’t moved an inch toward your transitional equilibrium.
Speaker 1: They are a specific regional exception. Yes.
Speaker 2: No, they’re the proof that convergence isn’t a law of nature. It’s a function of economics. This proves that local economic context, specifically wealth in the ability to buy cars and land overrides your scaling law. The homogenization we’re seeing elsewhere, this rush to the transitional state in Africa or Asia is simply the rest of the world copying a flawed model. Or maybe getting stuck halfway to the American model because they don’t have the wealth to sprawl as disastrously as Houston yet.
Speaker 1: That’s a pretty cynical interpretation. I view the land rich exception as a case of path dependency. Large cities are like supertankers, they turn slowly. The study even mentions that large to very large cities were less dynamic. American cities have massive existing infrastructure highways, suburbs that lock them in. Look at the rest of the world. The data shows that national regionalization is blurring. In 1990, the shape of a city was heavily dictated by its region. By 2015, that regional signal is weak. The global trend is stronger than the local tradition. The land rich countries are just the farthest behind the curve because they have the most inertia.
Speaker 2: That is a very convenient way to wave away the wealthiest most planned economies on earth. Let’s look at the transitional convergence itself. You seem to view this shift as a correction, a move toward efficiency, but look at what is actually happening on the ground.
Speaker 1: In many cases, it is a correction. Look at Latin America had cities that were fragmented complex in 1990, inefficient sprawled that actually densified and moved into the transitional cluster by 2015. They reduced their open space ratios, they became more compact. That is a positive trend towards sustainability.
Speaker 2: That is the cherry picked positive story. Now, look at Africa and Southeast Asia. You had ragged small cities, those permeable high edge density cities I described moving into transitional for them. This isn’t densifying, it’s sprawling. It means filling in the green gaps with concrete. It means expanding outward. The study explicitly links the transitional phase to processes of fragmentation for these cities. So for a developing nation, converging means degrading their efficiency. They are adopting this transitional mush, losing the tight urban fabric that actually worked for their climate.
Speaker 1: But ragged small isn’t necessarily efficient. It’s often a sign of underdeveloped infrastructure. As a city grows, it needs to fill in those gaps to provide services. You can’t run a subway system through a ragged small ink blot. You need density. You need a contiguous urban form. The shift to transitional represents the maturation of these cities into functional economic engines.
Speaker 2: Maturation implies they’re growing up. I’d argue they’re growing out. And this brings us to the most critical part of this study. The small cities. The authors highlight that the most dynamic changes are not happening in the mega cities. Tokyo and New York basically set in stone. The real action is in the small to medium cities, those under 500 square kilometres.
Speaker 1: Zuni in China, or smaller hubs in Nigeria. These are the cities driving this global homogenization. They are the metabolism of the system growing and reshaping themselves most aggressively. To me, this just confirms the evolutionary theory. These young agile cities are rapidly adapting to the global standard because it’s the most robust solution to housing millions of people.
Speaker 2: The tragedy here is the speed. A mega city takes decades to shift its form, but a city like Zuni, they’re doubling in size and shifting their form in a single generation. They’re laying down the concrete right now that will dictate their carbon footprint for the next century. And the data shows they are blindly copying the transitional mean rather than innovating for their local climate. We are missing a massive window of opportunity. Opportunity for what? For localization. This is the moment where we could implement local planning. We could design Sova to handle tropical rains and rising tides by keeping its ragged edges. We could design Zuni to respect its specific topography. Instead by letting them drift into this homogenized transitional blob. We’re letting global trends dictate the shape of future mega cities. We are standardizing them before they’ve even fully formed,
Speaker 1: but standardization is exactly what allows for scalable solutions. This is the crux of the argument for globalization. If we treat every city as a unique precious snowflake that needs a bespoke urban plan, we will never meet the challenges of the 21st century. We have SDG 11 sustainable cities. If we know that most small cities will inevitably become transitional due to these scaling laws, we can stop fighting the tide. We can design interventions, energy grids, transit systems, sanitation. That fit this specific transitional spatial profile, we can mass produce sustainability.
Speaker 2: Mass produce. Sustainability is an oxymoron when it comes to ecology. You cannot mass produce a relationship with the land. The study discusses the concept of biotic homogenization. It’s a parallel to what we’re seeing in the concrete when urban forms look the same, when they have the same spatial arrangement, the same patch density, the same lack of open space biodiversity suffers.
Speaker 1: You’re equating the shape of a city block with the extinction of species. That feels like a leap.
Speaker 2: It is not a leap. It’s a direct correlation. Different species thrive in different urban edges. If every city becomes a transitional medium density blob, you destroy the niche environments. You end up with a world where only the pigeons and the rats survive because they’re the only ones adaptable enough for that specific geometry. A transitional city in the Amazon rainforest and a transitional city in the Sahara Desert, they shouldn’t exist. Their physical forms should be radically different to support their local biomes, but the data shows they’re looking more and more alike.
Speaker 1: I see the concern about biodiversity. I do, but we have to prioritize the human species. Here. The study analysed the ratio of open space or ROS. It found a significant decrease in the mean values of open space across all clusters. In 2015, every single type of city is losing its breathing room. You might call that a tragedy. For the local birds. I call it densification and density is the single most important factor in reducing human carbon emissions.
Speaker 2: Is it? Or is it just creating urban heat islands?
Speaker 1: A city with less open space is a city with shorter commute times less per capita infrastructure and lower energy costs. The reduction in open space means we are fitting more people into a smaller footprint. If transitional means denser than the American suburb, then that is a win for the planet. We are effectively engaging in land sparing by concentrating our populations,
Speaker 2: but transitional also means more fragmented than the compact city. That’s the trap. It’s the worst of both worlds. You lose the cooling effect of the open space, but you don’t gain the true walkability of the traditional compact city. You get this middling, murky urban fabric that requires air conditioning to be liveable and cars to be nav. The heat maps don’t lie. By reducing open space everywhere, we’re creating ovens, and because we’re doing it globally, we are creating a monoculture. And as any farmer knows, monocultures are uniquely susceptible to disease. In this case, the disease is climate change.
Speaker 1: I would argue that a monoculture is also easier to treat if we have a standardized urban form. We can deploy standardized cooling technologies. We can model the airflow of a transitional city in a computer and apply the solution to a hundred cities at once. The global homogenization, the authors describe allows us to understand cities not as isolated, mysterious local accidents, but as predictable parts of a global system. We can upgrade them at scale.
Speaker 2: Treating the monoculture assumes we have the cure. I’m arguing we’re spreading the virus. I wanna circle back to the land Rich West because you dismiss them a bit too easily. The persistence of the fragmented complex cities in the wealthy west is a huge warning sign. It tells us that when people have the means, they choose sprawl, they choose privacy, they choose the car,
Speaker 1: they choose it because the infrastructure forces them to,
Speaker 2: isn’t an equilibrium, it’s just a waiting room. As the transitional cities in Asia or Africa get wealthier, who’s to say they won’t push right past transitional and end up as fragmented, complex sprawl monsters. The goal of the transitional city is to eventually become a wealthy, sprawled fragmented city. Then we aren’t co-evolving towards sustainability. We are co-evolving toward exhaustion,
Speaker 1: but the data doesn’t support that projection. The flow diagrams in this study show cities moving out of fragmented complex and into transitional In places like Europe and Latin America, the gravity is pulling toward the centre, not toward the American model. The American model is the dinosaur here. The transitional form is the mammal smaller, more adaptable, and it’s taking over the ecosystem.
Speaker 2: I hope you’re right about the direction of that flow, but even if we stop at transitional, we’re losing something profound. We are losing the sense of place. We’re essentially building the same city over and over again. Whether you land in a plane in Nigeria, Brazil, or China, the view out the window is becoming identical. A transitional mush of midden concrete. We aren’t just losing biodiversity, we are losing the cultural identity expressed through architecture and urban planning.
Speaker 1: Cultural identity is important, but housing 8 billion people is urgent. The transitional city is the reality of the 21st century. It is the emergent property of a connected world. We can’t force cities to remain ragged, small quaint villages to satisfy a tourist’s desire for difference, nor can we force them to be compact gray fortresses. They are finding their own. Our job as scientists, as planners, is to optimize that level,
Speaker 2: and I maintain that finding their own level is just a polite way of saying succumbing to unmanaged growth. While the metrics show convergence, the implication is a loss of resilience. We are standardizing our built environments at the cost of local ecological fit. We are trading the wisdom of the local biome for the convenience of the global grid.
Speaker 1: It seems we’re at an impasse on the philosophy. But United on the data, the transitional city is here and it is taking over. Whether that’s a triumph of systems theory or a tragedy of planning. That’s the question.
Speaker 2: Exactly. And the challenge now is can we make the transitional city sustainable or have we just standardized our mistakes?
Speaker 1: That is the question for the next decade of urban science.
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