Blaming the suburbs for harming the environment sometimes seems as simple as adding low-density living to single-occupancy driving. But studies of greenhouse gas emissions have come out surprisingly mixed. Some researchers find that suburbs contribute more damage to the climate than cities, but many see cities as the biggest total (if not per capita) contributors. Still others fail to find any strong connection between energy use and urban form.
Now a group of Canadian researchers would like to remind us not to leave one area out of the conversation: the exurbs.
Most energy studies estimate greenhouse gas contributions of a broad region. The new work, led by Jeffrey Wilson of Dalhousie University in Canada, used a unique data method to isolate the housing and transportation emissions of 1,920 individuals in the Halifax region of Nova Scotia. In an upcoming issue of Energy Policy, Wilson and collaborators report that each person in the exurbs, on average, was responsible for more emissions than someone from the suburbs or the inner city:
Efforts to reduce greenhouse gas emissions must also include the exurbanites. Those living in commuter belt zones and on the rural fringe have substantially higher greenhouse gas emissions, and particularly higher transport-related direct GHG, which often get overlooked in a policy debate that has focused on an urban (inner-city) versus suburban dichotomy.
Broadly speaking, and in keeping with conventional wisdom, the researchers found that total emissions increased away from the urban core:
But they also found that the difference between individual emissions of suburban and city residents was statistically negligible. While suburbanites had higher transport-related emissions (largely because they drove more), people in the city had higher home-energy emissions (largely because they had fewer household members to spread the electricity bill around). As a result, their total averages were more or less even:
Our findings indicate that individuals living in the suburbs generate similar amounts of GHG emissions (20.5kgCO2e person-1 day-1) to those living in the inner city (20.2kgCO2e person-1 day-1), challenging a widely held assumption that living in the urban centre is better for sustainability.
People in the exurbs, however, could not keep up. Median greenhouse gas emissions in these remote areas were 11 percent higher than in the inner city. Most of the problem came down to transport emissions, which were three times greater than those in the city (and 1.5 times those of the suburbs). Exurbanites had rather low housing-related emissions, but not low enough to keep their total average down.
The work suffers a number of notable setbacks. First, the very point of the work was to isolate individual greenhouse gas contributions, but the sparseness of the exurbs means the total emissions from this region no doubt remain rather low. It's also quite possible that income-level played a considerable role in the findings, as the Halifax exurbs are generally wealthier. Finally, the data were collected over a year, though ideally energy use would be compared by season.
That said, energy use remains at its core a personal problem, so it's extremely helpful to know where to target individual interventions. And, if nothing else, the findings let people in suburbs and cities suspend their own rivalry for a moment, and point their fingers somewhere else.