The Kind of Solution A City Is

A while ago I wrote about Jane Jacobs’ insight that cities were complex systems[i].  The stone that she dropped in the urban pond in 1961 has rippled widely, and the ideas of cities as complex adaptive systems, with emergent properties, good and bad resilience, and non-linear dynamics now guide much cutting edge urban research.
Of course, when Jacobs used the word problem, she meant an intellectual problem to be solved, and her answer suggested complex systems theory as an approach to understanding cities.  But the word “problem” also calls to mind an antonym.  To every problem there might be considered to be a solution.  In this spirit, with apologies to Jane Jacobs, I ask what kind of a solution a city is.
To get to my answer, I do have to admit that some urbanists have interpreted cities as literal problems, in the negative sense.  For example, members of the Chicago School of Urban Sociology in the 1920s emphasized urban pathologies.  They contrasted the issues that existed in cities with the ideal of village and rural life as they experienced it in turn of the 20th century America.  They studied such things as competition among immigrant communities and the distribution and behavior of gangs.  Of course, there are real negatives associated with cities, including pollution, disease contagion, crowding and stress, for example.  Recent research by Bettencourt and West (2010) has pointed out several negative factors, such as crime, that increase at greater than linear rates with city size.

The Lure of the City

A design for urban farming in vacant lands in West Baltimore.
From an urban design studio supervised by Brian McGrath
and Victoria Marshall.
In spite of the negatives of urban living, cities continue to draw humanity to them.  Urban areas are seen as a solution by societies, governments, individuals, and households who vote with their feet or with their policies.  Edward Glaeser (2011) has discussed at length the draws that urban areas clearly hold for people and institutions.  For instance, cities in the broadest sense, are a prime locus of innovation.  The serendipitous interactions of knowledge workers in cafes, bars, restaurants, and informal gatherings are important sources of new ideas and approaches.  Interestingly, the well known power of social media, which can theoretically operate at a global scale in service of creativity, have not replaced the sparks of face-to-face interaction among diverse people.  Institutions such as businesses and universities clearly recognize the power of the city as a source of creative interaction. 
But individuals also yearn for the city for their own reasons.  People seek access to health care, education, jobs, consumer goods, and excitement.  In particular, some urban migrants seek release from the strictures of tradition, the anonymity to pursue a lifestyle not sanctioned in a less urban setting, or to replace a livelihood taken away by industrial agriculture or resource exhaustion in the countryside.  These lures, presented briefly in narrative form can be considered the services or opportunities provided by urban areas. 
Economies of scale are another way to address the lures of the city.  Again, Bettencourt and West (2010) provide statistical meat on the narrative bones.  They show over a range of city sizes a clear savings in terms of per capita infrastructure, resource use, creative products, and so on.  There is roughly a 15% savings in many areas of urban structure and process compared to urban population size.  In a sense, cities and larger urban areas exist to provide these solutions, these lures.

The Contexts for Solutions: Four Dimensions

“The” city is not just one kind of solution, however.  McHale and colleagues (submitted) identify four dimensions of contemporary urbanization: Diversity, Complexity, Diffuseness, and Connectivity.  These four characteristics are intertwined and interacting.  Together they describe what is new and exciting about cities for an urban ecologist.  The conceptual space identifies the realms in which new solutions for sustainability and resilience can be sought in urban social-ecological systems.
Diversity.  Looking at urbanization and urban change around the world reveals a vast diversity of forms.  The wealthy urban cores of Europe surrounded by less well off or segregated suburbs; the Post-World War II sprawl of the United States with thinning and sometimes even shrinking cores; the megacities or Asia; the metropolises of India and Latin America dotted with favelas and shantytowns; the urbanizing former rural “homelands” of South Africa are a part of the great global diversity of urban settlements.  No single simple model describes all the urban systems around the world, or even in a single country any more.
Complexity.  The early history of cities was marked by compactness and often clear differentiation of districts of cosmological significance, trade, residence, and so on.  Cities have always been characterized by heterogeneity of social groups and social standing.  Today, urban areas are marked by great heterogeneity within their perceptual or legal boundaries.  Neighborhoods occupied by different ethnic groups are cheek by jowl, formal and informal institutions divide up the space of service or influence, networks of transportation span walking, public modalities, private vehicles, and opportunistic sharing.  Such networks are layered and changing, and intersect with the patchiness of economic, social, biological, political, and governance features.  Urbanists continue to remark on the stark heterogeneity of urban areas – cities, suburbs, and exurbs – even as the grain size and patch configuration shift with time and use.
Diffuseness.  Hand in hand with complexity is diffuseness.  The boundaries within urban areas are often porous and functionally indistinct in contemporary urban mosaics.  Commuters move great distances, and the direction of travel is often not in a peripheral to central direction.  Many places that had been considered peripheral under older conceptions of single metropolitan cores are now destinations for travel that avoids such cores.  Diffuseness also extends to governance and institutional arrangements.  The issues and solutions for environmental and social problems are managed by collections of governments, non-governmental organizations that operate at various scales, and linked civil society activities.  Likewise investments and disinvestment span neighborhoods, districts, municipalities, and different kinds of lands in extensive urban-rural agglomerations. 
Connectivity.  Closely linked to diffuseness is connectivity.  The porosity of official and vernacular boundaries within urban regions means that connections between the different areas and included ecosystem types can be extensive.  But this connectivity now goes well and commonly beyond any particular urban node or region.  Global connections of finance, resources, wastes, cultural influences, talent, and livelihood are rife.  Consequently, teleconnections or connections at a distance are now contribute much to the form and functioning of urban regional landscapes.  These connections affect farms, rangelands, forest lands, marine and coastal fisheries, for example, as well as more obviously urban places.

Implications for City as Solutions

A typology of water management designs based on how
they use vegetated and non-vegetated components.
Figure by Brian McGrath, Urban Interface.
The global and regional “facts on the ground” of diversity of type, spatial complexity of mosaics, diffuseness of various boundaries in urban territories, and the connectivity at local, regional, and global scales, must be accounted for in solving urban problems.  Indeed, how to exploit these facts is an open question for improving urban sustainability. 
The diversity of urban forms means that there is the opportunity for trying different solutions in different kinds and contexts of urban systems.  It also means that solutions must be locally tuned and evaluated. 
Complexity means that solutions are likely to be heterogeneous even in a single urban region.  Adaptive approaches to governance, including that by formal and by informal institutions, are likely to be required across complex urban regions. 
Diffuseness means that solutions – and problems – will sometimes not respect formal boundaries.  Highly localized control and decision making cannot succeed without at least accounting for the positive and negative effects on adjoining patches or ecosystem types, neighborhoods and districts.  In fact, governance in both its formal and informal manifestations can take advantage of positive outcomes of diffuseness of solutions.
Finally, connectedness means that problems and processes at great distances may have profound effects on any given urban ecosystem.  The accessibility of global markets to global factories and the length of global supply chains means that cities are at the whim of corporate decisions and lifestyle changes in countries and continents distant from their local control.  Solutions must be sensitive to such global connectivity.  Chasing investment that may itself be ephemeral in its geographic focus is a significant challenge.  Environmentally sensitive attempts to buffer a system from capricious decisions elsewhere are certainly called for, but planning for adaptive resilience rather than relying only on the rigidity of hard buffers is a major opportunity.

The Inclusive Sustainability of the Urban

A final opportunity for solution exists.  As the world population becomes increasingly urban, there may be a tendency to forget about the needs, wellbeing, and influences of those who still live in areas designated as rural.  Some nation’s policies are intensely urban focused, such as in China.  Other countries, such as those in Africa, face projected increases in populations such that the urban tide cannot help but rise.  Rural invisibility is a danger in such situations.  Not only must new and existing urban residents be protected from the vulnerabilities of rapid or ill-placed urban development, and exclusion from decision making processes about social and environmental services, but rural residents are at risk as well in this transition.  The connectivity of the urban and the rural in rapidly urbanizing countries is extraordinary.  In Asia and in Africa, for example, “circular migration” for work and in cities and the resultant disruptions of social capital in both city and countryside are existing or emerging issues.  In China, for example, the problem is recognized in policies of “urban-rural integration” which aim to narrow the gap in wealth and services between village and city residents. 
The diversity, complexity, diffuseness, and connectivity of urban settlements and rural and wild lands around the world, in specific municipalities, and in urban megaregions means that sustainability itself becomes a spatially and conceptually complicated set of goals and trajectories.  The kind of solution a city is likewise becomes a multi-dimensional, spatially extensive approach to sustainability.


Bettencourt, L. and G. West. 2010. A unified theory of urban living. Nature 467:912-913. 
Glaeser, E. 2011. Triumph of the city: how our greatest invention makes us richer, smarter, greener, healthier, and happier. Penguin Press, New York.
McHale, Melissa R., STA Pickett, Olga Barbosa, David N Bunn, Mary L Cadenasso, Dan L Childers, Meredith Gartin, George Hess, David M  Iwaniec, Timon McPhearson, M Nils Peterson, Alexandria K Poole, Louie  Rivers III, Shade T Shutters, and Weiqi Zhou.  A New Global Urban Realm:  Complex, Connected, Diffuse, and Diverse Socio-Ecological Systems. Sustainability, submitted.