Note: This article is part of a collaboration between Island Press and Public Square on a series of articles based on recently published books on subjects related to urbanism.

Cities affect our lives in profound, self-reinforcing ways: they can be a source of economic innovation, a pathway for poverty reduction, a brake on logarithmic demographic growth, and a solution to climate change—or they can reinforce economic isolation, heighten environmental impacts, and engender social strife. They represent 80 percent of global economic output and 70 percent of total energy and greenhouse gas emissions. Cities are the superstructure for the culture, lifestyles, aspirations, and well-being of half of the world’s population today and an estimated 70 percent by 2050. If they fail and become matrixes of gridlock, poisonous air, economic segregation, and environmental pollution, the planet will follow. If they succeed in lifting the next generation into sustainable productivity, integrating immigrants and working families into the next economy and living lightly on the land, they will contribute significantly to a civilized and sustainable future.

Although issues and solutions in individual cities are unique, many of the best urban development strategies are universal and simultaneously address social, economic, and environmental challenges. Mixed-use, walkable, economically integrated, and transit-rich places define good urbanism in any city. More often than not, the positive outcomes that result cost less in upfront infrastructure, ongoing maintenance, and the average household cost of living. Cities that persist in low-density development that isolates activities and income groups and has poor transit will heighten economic and social ills as well as emit more carbon. The latter effect has become a global crisis, especially in the developing world.

The developing economies of the world will account for the vast majority of urban growth in the next half century. More than 90 percent of urban growth is occurring in the developing world, adding an estimated 70 million new residents to urban areas each year, much of it in the world’s poorest regions. However, it is the emerging middle class within cities that drives carbon emissions, not the poor: 86 percent of energy-based carbon emissions come from upper-income populations. Therefore, it is the upper economic half of the global population that must adjust. Those economies and cities that are transitioning to a higher standard of living in the developing world must lay the groundwork for sustainable, low-carbon futures. In these cities, sustainable urbanism—places that are compact, mixed-use, walkable, and transit-oriented—is essential.

It is important to keep in mind that regions and cities struggling with extreme poverty are not the source of the planet’s climate change problem. Urban citizens in the developing world typically account for just one-twentieth to one-hundredth of the per capita greenhouse gas emissions of people in high-income nations, making carbon emissions in developing countries a lower priority. The average person worldwide accounted for 4.9 tons of carbon dioxide (CO2) emissions in 2011, whereas the bottom quarter of the global population emitted only 0.3 tons per capita and the second quarter emitted 1.5 tons—slightly below the world target of 1.6 tons per capita for 2050 identified by the Deep Decarbonization Pathways Project. These populations do not own cars or air conditioners, live in large homes, or eat steaks. If they succeed in the next 30 years, their carbon emissions will still be reasonable.

Urban sprawl in the developing world has many manifestations and just as many challenges. Clean water, adequate sewage treatment, consistent power, social services, affordable housing, gridlock, health care, economic development, and environmental decay—these are a short list of chronic issues in emerging cities. These challenges are all interconnected in a self-reinforcing cycle that either enhances or destroys opportunity and progress. And, in a systemic way, the form of the city affects each of these challenges. Urbanism at its best reduces per capita environmental demands while it makes services, infrastructure, and economic development more efficient, more cost-effective, more accessible, and more interconnected.

There are three types of sprawl challenging cities around the planet, two of which dominate the developing world: high-density sprawl, which is unique to China, and low-income sprawl, seen across Latin America, Africa, and much Urbanism and Global Sprawl of Asia. Although such a taxonomy is reductionist and simplistic, it helps identify characteristics that cluster issues and opportunities in ways that are useful. The third type is the well-known North American version of sprawl, so-called high-income sprawl, which has low densities, isolated uses, and an auto-dominated transportation system. Put in the context of the developing world, its most salient difference is that, since World War II, the wealthy and middle class have abandoned the city for suburbs.

Low-income sprawl dominates most of the developing world. In this case, relatively low-density housing at the metropolitan edge isolates the poor from access to jobs and services, while the wealthy remain in the urban center along with the concentrations of jobs and economic opportunity. Here, the low-income population—those most in need of economic and social access—are isolated and condemned to debilitating commutes on substandard transit. In contrast, the high-density sprawl typical in China does not isolate the poor at the urban edge, but it builds housing towers in a single-use “superblock” pattern that compromises local connections, walkability, and transit. Even though development is dense, land uses are isolated in the superblocks and surrounded by vast arterial roads, compromising the fundamental fabric of a healthy city: walkable streets and convenient transit.7

China’s high-density sprawl

Of the two types of sprawl infecting growth in the developing world, high-density sprawl, found mainly in China, is unique, ironic, and tragic. One thinks of the high-rise, high-density buildings in many Chinese cities as inherently urban, but they are not. Smart growth and urbanism is more about connections, human scale, walkability, and mixed uses than it is about gross density. China’s pattern of gated superblocks (often over 40 acres, or 16 hectares, each) and isolated uses is actually a high-rise version of the American suburb or a literal version of the failed American low-income projects of the 1950s and 1960s.

Chinese high-rise superblocks.

In China, single-use residential blocks of largely identical units are clustered in superblocks surrounded by major arterial roads. Vast distances separate everyday destinations and create environments hostile to pedestrians. Sidewalks rarely are lined with useful services, and crossing the street is death-defying. Job centers are distant and commutes are long, especially for lower-income groups. In major Chinese cities, the gridlock expands to all hours of the day. The simple truth is that an auto-based city, even at low densities, cannot work. At the scale of China’s development and density, it is impossible, no matter how many freeways and ring roads are built.

In the last five years, China has built more than 30,000 kilometers of expressways, finishing the construction of 12 national highways a whopping 13 years ahead of schedule and at a pace four times faster than the United States built its interstate highway system. Over the last decade, Shanghai alone has built some 2,400 kilometers of road, the equivalent of three Manhattans. China’s urban population is projected to grow by 350 million people by 2020, effectively adding today’s entire U.S. population to its cities in less than a decade. China already has passed the United States as the world’s largest automobile market, and, by 2025, the country will need to pave up to an estimated 5 billion square meters of road just to keep moving. With it all has come gridlock and poisoned air.

Nonetheless, China’s love affair with the car has blossomed into a torrid romance. Recently, nearly 1 million people poured into the Beijing International Automotive Exhibition to coo over the latest Audis, BMWs, and Toyotas. And, like the U.S. cities of the 1950s and 1960s, Chinese cities are working to accommodate the explosive growth of automobile travel by building more highways, ring roads, and parking lots. But China is in danger of making the same mistakes that the United States made on its way to superpower status—mistakes that have left Americans reliant on foreign oil from unstable parts of the world, staggering under the cost of unhealthy patterns of living, and struggling to overcome the urban legacy of decades of inner-city decay. The choices that China makes in the years ahead will have an immense impact not only on the long-term viability, livability, and energy efficiency of its cities, but also on the health of the entire planet.

If anything, due to China’s high population density, the Chinese urban reckoning will be even more severe than that in the United States. Already, traffic in Beijing is frequently at a standstill despite the incredible pace of road construction (a “solution” akin to trying to lose weight by loosening your belt). The situation is so dire that Beijing, Guangzhou, and Shanghai are using a lottery to allocate a limited number of vehicle registrations. In August 2010, a 96-kilometer (60-mile) traffic jam clogged a highway outside Beijing for 11 days. There is a reason that no high-density city has ever been designed around the car: it simply does not work.

The form of China’s urban growth also will shape much of the country’s environment—and not for the better. As Beijing orders up ever more freeways and parking lots, walking, biking, and public transit are declining. Since 1986, auto use has increased sixfold in Beijing, whereas bike use has dropped from nearly 60 percent of trips to just 17 percent in 2010. The congestion, air quality, and greenhouse gas impacts of this shift have been massive: Beijing remains one of the world’s most polluted major cities. Merely to ensure blue skies during the 2008 Olympics, the city spent some $17 billion restricting traffic and shutting down factories. It even employed 50,000 people to fire silver iodide at clouds to release rain. The health damages caused by local air pollution, resulting largely from auto use and local coal and oil combustion, are very large: China’s air pollution was linked to 1.2 million premature deaths in 2010—or, put in monetary terms, damages equivalent to 9.7–13.2 percent of the country’s gross domestic product (GDP). (See Figure 7–1.) The problem is so severe that curbing local air pollution has become a major item on the government’s policy agenda, driving plans to curb China’s coal consumption.

Across China, injuries to drivers, pedestrians, and cyclists are on the rise. From 1992 to 2004, the bicycle-related mortality rate increased 99 percent in Shanghai. Traffic fatalities in China are a severe problem by any measure, with various estimates ranging from 160 to more than 700 per day, among the highest in the world. The underlying reason for these trends is no mystery: bad urban planning.

At the center of this planning is the superblock: a weapon of mass urban destruction developed in 1935 by the Swiss architect Charles Edouard Jeanneret (better known as Le Corbusier) and embraced wholeheartedly by China’s efficiency-minded traffic engineers. Based on a network of wide, arterial streets, China’s superblocks feature large, single-use development areas, often more than a quarter mile (0.4 kilometers) per side and designed like barracks, inconveniently located far from workplaces and shopping centers. The goal is to move cars efficiently; people are an afterthought. The ironic result is an alienating landscape that makes walking and biking difficult, which in turn increases congestion on the streets, with all the attendant social and environmental costs. Culturally, it is a tragedy for Chinese cities, which are seeing traditional neighborhoods, where friends and family could easily pop in for tea and conversation, destroyed by misguided development. Now, people have to take a crowded bus or, if they are lucky, a car.

Traditional Chinese settlement pattern

The congestion will only get worse. The international consulting firm McKinsey projects that nearly 64 percent of China’s population will live in urban areas by 2025, up from 48 percent in 2010; by then, there will be 221 Chinese cities with more than 1 million people. Can China afford it? Transportation already accounts for 40 percent of China’s oil demand, according to the International Energy Agency, and is expected to reach 65 percent by 2035. The Carnegie Endowment for International Peace projects that the country’s vehicle fleet could grow from more than 200 million today to as many as 600 million by 2030. By that year, oil consumption is projected to have nearly tripled. Needless to say, finding all those resources is going to be a challenge— that is, if Chinese cities don’t choke on pollution and gridlock first.

The figures are daunting. But the engineers who run the Chinese ship of state are nothing if not good at math, and they have committed to making real changes: building mass-transit systems, introducing alternative fuels such as ethanol, and promoting fuel efficiency and electric cars. There are still other things Chinese cities can do at the margins, such as introducing the sorts of “congestion pricing” schemes—taxes on vehicles as they enter certain areas—that have worked wonders in places like London and Singapore. Unfortunately, numerous studies have shown that the numbers don’t quite add up, as these technical fixes tend to ignore China’s fundamental problem: cities designed around cars, not human beings.

The problem is not just the increase in cars in high-density environments; it is the coarse nature of the typical Chinese road network as well. The current unholy alliance of superblocks and oversized arterials not only frustrates pedestrians and cyclists, but it fails for cars as well. An arterial system of wide, “canyon-like” streets creates a hostile environment for pedestrians and bicyclists. Wider streets lead to increased crossing distances, longer distances to intersections for pedestrians, higher traffic concentrations on fewer roads, few alternative routes for emergencies, and complex traffic movement at intersections that threaten pedestrian and bicycle comfort and safety. Often with few entrances, superblocks add to the circuitous access routes for cars as well as pedestrians.

Crosswalks on a massive arterial in Kumming, China.

The alternative is a more traditional city grid of streets with higher intersection density and a broader range of street types. In this tried-and-true street network, high volumes of through-traffic are dispersed over parallel and smaller roads or onto pairs of one-way streets. Pedestrian and bike zones are protected and enhanced on all streets. Transit lines and bus rapid transit (BRT) systems gain dedicated lanes, and auto-free streets enhance alternate modes. Such a street network creates a radically different urban landscape, one that replaces China’s isolated superblocks with small courtyard blocks. Streets are the DNA of a city; their scale and how they mix public spaces, shops, pedestrians, bikes, and cars is critical to the health of a city.

The transportation and carbon emission problem in China cannot be solved without fundamental changes in urban design and land-use planning. For the past five years, the Energy Foundation has sponsored demonstration projects in six Chinese cities with planning for a combined population of over 10 million to show that the alternative is feasible, efficient, economically strong, and socially advantageous. The projects have worked so well that the national government has adopted design standards for areas within walking distance of transit stations that reinforce walkability, mixed-use, and smallblock urban design. These transit-oriented development (TOD) standards, adopted in 2015, ultimately will affect a growing population as the national investment in high-capacity transit expands by 10,000 kilometers in the next 10 years.

The use of small blocks is a radical departure from the superblock pattern prevalent in most of China. As a result of this more-diverse street network, small blocks create a human-scaled environment of shared courtyards; smaller, more walkable, local streets; a fine-grained network of public spaces around the blocks; and a greater land-use mix in a smaller area. (See Figure 7–2.) This structure, along with the presence of only one-quarter of the inhabitants of a superblock, enables a stronger sense of community. The intrinsic courtyard pattern recalls the historic city forms throughout China, from the traditional hutong courtyard housing to the form of the Forbidden City. It emerges here at a different scale, but provides the same urban layering, from public street to semi-public courtyard to private home.

The typical small block measuring 300 to 600 feet per side, results in 400–700 dwellings—housing at most 1,500 people. This number is small enough for most people to recognize one another and establish strong social connections. In contrast, superblocks contain easily 5,000 people, a scale in which many people become anonymous and children are more frequently exposed to strangers. In addition, small blocks increase the opportunity for the kind of street-side shops and local services that support street life and neighborhood identity.

The Energy Foundation conducted studies in Jinan in which people from a variety of neighborhoods recorded their trips and distances. Regardless of income, the average citizen living in a superblock drove four times the distance as others living in more walkable mixed-use areas. This fourfold increase, if expanded by more superblock construction, will cascade into traffic jams, polluted air, more energy imports, and more carbon emissions. Over the next 20 years this difference alone could represent massive quantities of new CO2 in the air.

In 2015 the central government issued new standards that not only require open, mixed use and walkable communities but actually attempt to open existing gated superblocks. These new standards are a urban design revolution: they overturn the destructive Chinese model of superblocks, gated communities, and giant streets that has been eroding the livability their cities. They are perhaps the most important application of global best practices in smart growth to date: including urban growth boundaries, compact mixed-use development, walkable environments, infill development, bikeways, auto free streets, transit-oriented development, green buildings, and the preservation of history, culture, agriculture and natural ecologies in urban development. They have been testing these ideas for years, but now they are moving them to a scale that is unprecedented.

China’s leaders have the resources and the wherewithal to make the sweeping changes required to avert an impending social and environmental disaster. Unless these ideas are successfully implemented, China’s powerful economic engines—its cities—will slowly grind to a halt.

This article was an excerpt from Can a City Be Sustainable? (State of the World) by the Worldwatch Institute, from a chapter written by Peter Calthorpe. Copyright © 2016. Reproduced by permission of Island Press, Washington, DC.