Cities Offer Solutions to Cutting Greenhouse Gas Pollution

Cities often get a bad rap for generating most of the globe's greenhouse gas pollution. But on a per person basis, it seems that urbanites are responsible for considerably less human-caused greenhouse gas pollution than those living in suburbs or rural communities.

David Dodman, a researcher with London-based International Institute for Environment and Development, compared the greenhouse gas emissions from cities around the world with national averages. He found that far from being climate criminals, "well-planned, well-managed cities can play a central role in helping to mitigate against climate change. This does not necessarily entail increasing densities (particularly in low- and middle-income countries) but, rather, an awareness of broader issues of the urban form and urban structure."

The research was published last month in the journal Environment and Urbanization.

In the United States, Dodson found that while New York City produced 29.7 percent of the nation's entire greenhouse gas emissions (ghgs) in 2005, each New Yorker produces about 7.1 tons of ghgs per capita, while in 2004 the average American was responsible for over three times that much -- nearly 24 tons. (The difference in years is due to different schedues for reporting ghg emissions, Dodson states.)

Figures for Toronto were similar. Using data from 2001 for the city and 2004 for Canada, Dodson determined that while Toronto produced 34.4 percent of the nation's ghgs, residents of the city were responsible 8.2 tons of ghgs per capita, compared to the national per capita average of 23.72 tons.

There are clearly cultural factors at work in addition to wealth to account for a nation's ghgs, because as Dodson notes, weathy nations don't gulps energy with equal rapacity. According to Dodson's findings, each resident of Tokyo produced 4.8 tons of ghgs in 1998, while the national average was 10.59 tons (in 2004).

What makes cities so much more energy efficient? Higher urban density lowers individual car ownership and increases reliance on mass transit, which in turn is more likely to be both present and effective thanks to that density. Also, the more dense built environment, and smaller than average homes and apartments, translates into using less energy to heat, cool, light and power buildings.

Dodson suggests that rather than criticize urbanites for how much energy they use, more prosperous nations -- which bear the greater responsibility for total ghgs over time -- should aim to decrease their energy use and consumption overall. Within these nations, he adds, the responsiblity must be accorded proportionally between "high-consuming elites" and lower-income and poor citizens.

Cities, he says, also need to get on the ball with mitigation strategies for the impacts of human-propelled global warming:

There is also the need to develop comprehensive adaptation strategies for urban areas, particularly in low- and middle-income countries. Hundreds of millions of urban dwellers in these countries are at risk from the direct and indirect impacts of climate change. These include: sea-level rise; an increase in the frequency of heat waves, storms and fl oods; and more gradual changes that increase risks or exacerbate resource constraints. There is a growing body of evidence demonstrating the dimensions of vulnerability in these settlements, yet there has been insuffi cient focus on appropriate methods and mechanisms for adaptation.

Dodson proposes that cities are the best acceleration labs for effective mitigation strategies. Urban authorities and local governments have the potential to speedily and effectively adopt mitigation programs and emissions reductions, he says, "because of the type of responsibilities they hold in relation to land use planning, local public transportation and the enforcement of industrial regulations."

Further, "[T]he concentration of people and industries in large cities provides
the opportunity for technological innovations," Dodson says, "such as combined
heat and power and waste-to-energy generation plants that can generate
electricity more effi ciently; and it also makes mass transit systems cost and
time effective."

Urban density "also provides the opportunity for the rapid spread and adoption of new ideas and innovations, both in technical and behavioural solutions," says Dodson.

For example, Ken Livingstone, the former Mayor of London, has stated that addressing climate change requires determination on the part of the city authorities, sophisticated fi nancial institutions to respond to carbon trading and investment technologies, and state of the art scientifi c and technical research facilities to develop the technologies of the future – a combination of features that can only be found in major metropolitan centres.

Innovation and improvements in lowering greenhouse gas emissions in cities create side benefits, he says. For example, reducing fuel use by expanding mass transit can make the streets safer for pedestrians, thus increasing physical activity, and decreases air pollution; both make for a healthier population.