Sprawling vs Compact City
Urban sprawl, i.e. expansion of cities into low density, single use development, is a growing problem across the world leading to loss of ecosystem services, air pollution, class segregation and increased energy use. It is mainly driven by population growth, housing preferences, demand for social security and aesthetic preferences. The key maintainers of sprawl are road infrastructure designed with automobile use in mind and government's intentional and unintentional support for city expansion. Many cities are beginning to realize the negative impacts of urban sprawl, and governments are working towards shifting from sprawling of cities to development towards a more compact structure. This is made by e.g. investments in public transportation and new compact and mixed used areas where automobiles are not necessary.
Key direct drivers
- Infrastructure development
- Environmental shocks (eg floods)
Key Ecosystem Processes
- Soil formation
- Primary production
- Nutrient cycling
- Water cycling
- Food crops
- Wild animal and plant products
- Fuel and fiber crops
- Air quality regulation
- Climate regulation
- Water purification
- Water regulation
- Regulation of soil erosion
- Natural hazard regulation
- Aesthetic values
- Knowledge and educational values
- Spiritual and religious
- Food and nutrition
- Health (eg toxins, disease)
- Livelihoods and economic activity
- Cultural, aesthetic and recreational values
- Social conflict
Typical spatial scale
Typical time scale
- Irreversible (on 100 year time scale)
- Contemporary observations
Confidence: Existence of RS
- Speculative – Regime shift has been proposed, but little evidence as yet
Confidence: Mechanism underlying RS
- Contested – Multiple proposed mechanisms, reasonable evidence both for and against different mechanisms
Links to other regime shifts
When discussing the two different regimes we will focus on the archetypes for compact city and sprawled city as large cities and megacities that still attract people. Thus, rather than a proper regime shift, development of cities is often path dependent according to one of the two trajectories towards either a sprawling city or a compact city. Our focus is on urban areas in developed countries, therefore we do not take e.g. poor city slums into consideration.
A compact city is more than just a city that is densely populated. "Dwelling density, the advancement of mixed-use development, and reaffirmed focus on the nature and quality of development have been identified as important aspects in the creation of the compact city" (Arbury 2005).Three elements are consistently found in many literatures that describe a compact city - mix-used development, greater focus on public transportation and quality urban design (Breheny 2001, Arbury 2005). Studies have included the promotion of urban regeneration, the revitalisation of town centres, and restraint on development in rural areas (Breheny 2001) and pedestrian friendly with large pavements (Arbury 2005) as part of the definition.
Urban sprawl can be defined as "unplanned, uncontrolled, and uncoordinated single use development that does not provide for a functional mix of uses and/or is not functionally related to surrounding land uses and which variously appears as low-density ...development" (Arbury 2005). The European Environment Agency (EEA) has described sprawl as the physical pattern of low-density expansion of large urban areas, under market conditions, mainly into the surrounding agricultural areas. Low-density, single-use and automobile dependent type of development has been the key attributes with lack of planning and control being the key enablers for urban sprawl.
Unfortunately, there is not one single measurement for compact city or sprawling city. It requires a set of indicators that incorporate economic, social and environmental attributes of city development. Furthermore, defining what is desirable is quite subjective to preferences held by residents of different cities, which implies what may be desirable for one city might be undesirable for others.
Drivers and causes of the regime shift
Shift from Compact City to Sprawling City
The main drivers and causes contributing to sprawl are urban population growth and the demand for housing. City expansion impels economic development, through the production of jobs, creativity, technology and the accumulation of knowledge and economic markets, which in many ways can lead to better welfare (Bairoch 1991). This induces the demand to live more spaciously, own a private lot and drive a car. Moreover, there are many people wishing to live closer to nature, hence people preferring aesthetic quality of the landscape seems to be contributing to sprawl development (Brown 2006). At the same time living in the inner city becomes more and more expensive and undesirable.
In Europe, many cities developed long before cars existed, and therefore have a more compact structure. Cities in North America, Australia and New Zealand, on the other hand, are planned for automobile use as a central part of the city system. Infrastructure, such as construction of roads, works as a feedback in the system and facilitates transportation. Increased private automobile ownership and low prices of fuel raises the automobile use even further. Another cause is the sudden rush of people to a city due to natural disasters (famines, flooding etc.) leading to uncontrolled sprawled or slum areas.
How the regime shift works
A compact city has a diversity of functions congregated at the same place. It is designed with a mixed-use construction, pedestrian friendly roads and alternative means of transport. Instead of a "laissez faire" trend in urban planning, there is usually conscious control of city expansion with urban intensification, investments in public transportation and urban quality design (Arbury 2005). The functions of a compact city are self-reinforcing since its structure promotes public transportation, biking and walking before automobile use, with housing, work and shopping within reasonable distances. However, city expansion without conscious planning usually results in the city sprawling, also in originally compact cities, which explains why many old European cities have a compact core but a sprawled periphery.
Thus, almost all cities have elements of both sprawl and compact development, and once an area is built, it is hard to change its structure. Therefore, there are no precise thresholds and there is no regime shift in its proper sense, but rather a path dependency towards either sprawl or compact development. This pattern is described by Scheffer and Carpenter:"For conditions in which alternative equilibriums exist, the initial state (i.e. place in the landscape) determines the equilibrium to which the system will settle"(2003).
The regime of a sprawling city refers to low-density development of urban areas with a single use structure. This means the functions of housing, service and work opportunities are separated into different areas in the city. Infrastructure of roads and the automobile use make transport between these areas possible, hence maintaining the system. In countries such as USA, Australia and New Zealand, many cities were constructed after the invention of cars, rendering less dense city centers suited for automobile use. This construction automatically implies a bigger risk of sprawling compared to older European cities. Population growth and demand for housing are the main factors that drive this system.
Impacts on ecosystem services and human well-being
Shift from Compact City to Sprawling City
Sprawl leads to loss of land, which could have a negative impact on all provisioning ecosystem services depending on what type of land that is removed. Examples of such provisioning services are food crops, livestock, fisheries, wild animals, plant products, timber, fuel, fibre crops and woodfuel. This also leads to loss of air quality regulation from trees. Furthermore, there is biodiversity loss affecting other regulating services such as pollination, carbon sequestration, pest control and disease control. Cities in general and the expansion of the cities in particular result in increased emissions of greenhouse gases. Cities emit 70% of the world's greenhouse gases, which have vast consequences for the climate (CDP Cities 2011).
Since sprawled areas consist of private owned lots, commercial centres and roads, there is a lack of public space (Arbury 2005). Thus, people who own a private lot gain from sprawl whereas others loose. The suburban residents get the advantages of living in a house, away from urban stress and insecurities, but still have access to work opportunities and activities in the city (Arbury 2005). Also pollution and car accidents have a bigger impact on inner city dwellers since cars gather in the centre (Ewing 2008). Segregation is another problem that increases with sprawl, leading to poorer health among people who are less well off (Arbury 2005). Shifting from a compact to sprawling city affects cultural services such as recreation areas, aesthetic values, knowledge, educational values and spiritual and religious values. The compact city model encourages people to use public transportation and to walk and bike more, which have a positive impact on human health. However, city life is often considered stressful and can contribute to mental strains.
Governments have an important role to play to ensure that feedback mechanisms enable sprawling cities to develop more effectively. An important first step is to formulate and enforce a city plan with wide public support (EEA 2006). Bold steps can be taken to abolish subsidies and other governmental support on outskirt road construction and "new town" developments. Full cost of providing public utilities, i.e. electricity, water and sanitation supply and waste treatment can be incurred to residents in newly developed areas (EEA 2006). Full cost of externalities from private automobile use can also be incurred through tax on vehicle ownership, fuel price and other schemes such as city tolls. Public finance from these resources along with savings from less road construction can be invested to promote inner-city mobility, such as investment on public transportation and bicycle and pedestrian roads. Without city planning, there will always be economic, social and environmental driving forces motivating people to move to the outskirts, as long as there is population growth. However, as long as the government does not allow feedback mechanisms of sprawl to be initiated, such as government support for road construction and large-scale outskirt development, or become too strong, this will be enough to prevent sprawl. This will enhance the resilience of the city to stay compact.
However, in order to restore a sprawled city back to a compact city, a comprehensive and balanced approach that fundamentally reverse all drivers and feedbacks are necessary (EEA 2006). Another possible approach will be to establish new feedbacks that lead to compact city structure. Foremost, inner city building structures should be transformed into mixed-use structure so that affordable inner-city housing becomes more accessible. City planners should be on the lookout for "windows of opportunity", i.e. brownfield projects, to turn unattractive urban areas into mixed used housing or urban green areas. Governments should work actively to prevent inner-city crime and improve environmental conditions in order to make living in the city more safe and attractive (Ewing 2008).
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