Suburban sprawl is a fact of life in US cities. White picket fence houses with a lawn and a nuclear family are powerful symbols of American life rooted in the lifestyle of suburban developments.
Despite the draw of suburbs, they have massive social and environmental costs when compared to more densely populated city developments. For this month’s blog post, in honor of our environmentalism month, I’ll be giving a brief description of 3 (out of many!) ways suburban sprawl ruins the environment.
Before we begin, it is important to understand what suburban sprawl actually is. While the specifics are heavily debated and vary region by region, its most basic characteristics are: Low population density, single use zoning, car dependency, and wide geographical area. Low population density refers to the small ratio of land to residents. Single use zoning refers to a style of land zoning in which residential, industrial, and commercial areas are physically separated from each other, restricted to certain “zones” in the city. Car dependency describes the need for residents to own a car in order to comfortably live and work, often due to a lack of walkability and public transit. Finally, suburban sprawl tends to, well, sprawl, taking up larger amounts of land than more-densely populated areas.
This post will focus on 3 particular effects of suburban sprawl:
Increased air pollution
Increased flooding
Loss of farmland
1. Increased Air Pollution
Vehicle tailpipe emissions are the single largest source of carbon emissions in the US, accounting for 28% of total carbon emissions per year. For perspective, electricity generation accounted for only 25% of total carbon emissions in the US.
Unsurprisingly, the car-dependency of suburbs is the main reason why vehicle emissions are so high. Suburban developments emit twice as much CO2 as more densely populated urban developments. While cars are driven in every type of residential environment, the characteristics of suburbs maximize the amount of time residents spend on the road, which by extension maximize vehicle emissions.
The long distances between residential areas and commercial areas force suburban residents to commute via car over physically longer distances, spending more time on the road by extension. As suburbs extend and get further away from the city center, this issue compounds, deadlocking residents into ever-increasing commuting times.
In addition, suburban development patterns lock themselves into a spiral of ever increasing traffic. In cities with intermixed residential and commercial zones, residents must all take separate roads to get to their respective employers. However, in cities with separated residential and roads, all residents in a certain zone must take the road that best connects them to commercial areas, regardless of their employers. Major roadways in suburban developments need to accommodate virtually every worker in the large residential zone they are connected to, whereas major roadways in mixed use developments need to accommodate a much smaller number of residents for a smaller amount of time. Think of it this way: the same number of people are on the roads in both mixed use and single use developments. However, in single use developments, they are all crammed onto one central roadway, instead of being distributed onto multiple different routes. Consequently, suburban developments amass deadlock congestion at much higher rates than other types of developments.
Suburban developments are a one-two punch of vehicle emissions: longer distances traveled on roads with heavier traffic.
2. Increased flooding
Hurricane Harvey, which hit Houston in 2017, was the 3rd most dangerous flood in American history. Water heights reached 5 feet for more than 4 days, causing 26 casualties and over 125 billion dollars in property damage. A recent analysis of the hurricane by Princeton researchers revealed that, when compared to more centralized cities, the sprawled design of Houston made hurricane floods 26 times more intense. Suburb design actively undermines natural flood control mechanisms, making natural water disasters all the more dangerous.
Floods form when the streams and basins fed by runoff precipitation become overflowed, no longer able to hold any more water. The excess water is re-routed to new drainage courses outside of typical water flows. These new, temporary waterways are what we know as floods.
One of the most important stopgaps in preventing floods is penetrable, water-retaining soil. It soaks up precipitation and stores it underground, reducing the amount of water that flows into basins and streams.
Suburban areas necessitate massively decreasing water-retention. Miles upon miles of roads, parking lots, sidewalks, and roofs are necessary for any suburb to survive. The few green spaces that are present in suburban areas, like lawns and road verges, have thin layers of artificial soils, which can only hold a small amount of water. Furthermore, the wide area of development that suburban areas occupy increases the size of the watershed, collecting more rainwater into central streams.
3. Loss of farmland
Low density developments, by their very nature, chew up land. Often, the land they require is high-quality arable farmland on the outside ridge of city limits, as houses with lawns and backyards carry high property values.
Between 1982 and 2003, 23 million acres of farmland were lost to suburban residential developments. Real-estate developers are willing to pay a premium for farmers’ land, giving farmers an incentive to sell their land. A domino effect takes place once an initial plot of land is sold, as adjacent lands gain higher values and get sold at quicker rates.
Farm relocations may seem harmless, but they are a driving factor behind deforestation. Relocated farmers might choose to cut down forests or clear an important habitat for cheaper land. In places like Arizona and New Mexico, research estimates that all farmland will be used up by 2033, presenting both an economic and environmental threat.
Solutions
In the case of suburban sprawl, it's hard to scrap it entirely and start over; it is literally set in stone in our cities. There are some things we can do retroactively to mitigate the impacts sprawl has had on the environment.
1. Greenways
Greenways are large plots of protected wilderness located in urban zones, providing high porosity soil to catch runoff.
2. Re-invest in public transportation
Providing high-quality public transportation is key to curbing emissions by decreasing the amount of individual automobiles on roadways. (For more information on public transit, check out last month’s blog post).
3. Mixed-use zoning requirements
Mixing commercial and residential zones together helps fight roadway congestion by distributing cars along more roads. Gradually replacing single-use zones with mixed zones, as well as implementing mixed zoning in future communities, would cut back on road length and congestion times.
4. Agriculture Zoning
Designating certain parts of land outside of cities as farmland only prevent residential developments from displacing the farms already present
It is impossible to build large cities without impacting the environment at all. However, we should constantly make an active effort to reduce the negative impact that our human settlements have on the sustainability of our surroundings.
Sources:
Sanders, Robert. “Suburban Sprawl Cancels Carbon-Footprint Savings of Dense Urban Cores.” Berkeley News, UC Berkeley , 9 July 2015, https://news.berkeley.edu/2014/01/06/suburban-sprawl-cancels-carbon-footprint-savings-of-dense-urban-cores/.
Depalma, Anthony. “Saving Farmland from Suburban Sprawl.” The New York Times, The New York Times, 3 Feb. 1985, https://www.nytimes.com/1985/02/03/realestate/saving-farmland-from-suburban-sprawl.html.
Wernick , Adam. “US Lost 11 Million Acres of Farmland to Development in Past 2 Decades.” US Losing Millions of Acres of Farmland to Development, 7 Aug. 2020, https://www.pri.org/stories/2020-08-07/us-lost-11-million-acres-farmland-development-past-2-decades.
Squires, Gregory D. Urban Sprawl: Causes, Consequences, & Policy Responses. Urban Institute Press, 2002.
Kahn, Matthew E. “The Environmental Impact of Suburbanization.” Journal of Policy Analysis and Management, vol. 19, no. 4, 29 Sept. 2000, pp. 569–586., https://doi.org/10.1002/1520-6688(200023)19:4<569::aid-pam3>3.0.co;2-p.