Most discussions on how to reduce your carbon footprint focus on what you drive and how well your house is insulated. Those issues are certainly vital, but the bigger issue may really be how much you drive and how big your residence is. And those, in turn, get you into the wonky subject of land use.
There is a growing sense among experts on of climate change that development patterns of communities are a key determinant of greenhouse gas emissions: People who live in more sparsely populated suburbs will inevitably drive more miles and will tend to live in larger homes that use lots of energy, no matter how well they are insulated.
The latest example of this new consensus is a report issued last week by the Metropolitan Policy Program of the Brookings Institution. News coverage of Shrinking the Carbon Footprint of Metropolitan American in outlets such as the New York Times focused on differences in per capita carbon emissions among metropolitan areas, which Brookings attributes primarily to factors such as differences in climate and power-plant fuel mix.
Yet the main message of the report is that urban areas overall play a key role in limiting greenhouse gas emissions thanks to the more compact structure of communities and the availability of public transit as an alternative to CO2-spewing automobiles. More densely populated areas, the authors note, also make more efficient use of electric, water, sewage and communications infrastructure.
This is true, they find, not only when comparing metro areas to non-metro areas but also to a certain extent among urban areas. Older cities such as New York, Chicago, Boston and San Francisco that have denser population distribution and more extensive transit systems are all low per-capita emitters, while sprawling, car-dependent metro areas such as Nashville and Oklahoma City rank high.
The authors admit there are exceptions to the rule. Washington, DC, for instance, has a relatively high level of transit use but also has an elevated level of per-capita CO2 emissions, largely because of the large amount of coal used by electric utilities in the region.
The Brookings report builds on prior research such as the path-breaking Growing Cooler report—written by a team led by Reid Ewing of the National Center for Smart Growth—which summarizes scholarship on the links between land use and climate change. A recent working paper by Evans Paull of the Northeast-Midwest Institute takes the discussion a step further and argues that brownfield and in-fill development projects within cities create the potential for even more dramatic reductions in greenhouse gas emissions.
Smart growth turns out to be smart not only for quality of life but also for quality of the climate.