An upside-down view of where ecological damage comes from

Robert Steuteville, New Urban Network

New Geography, the pre-eminent digital defender of US automobile-oriented policy, argues in recent articles here and here that suburbs are superior to walkable urban neighborhoods in environmental performance.

The claim defies sound reasoning and most scientific evidence. Not only do people have to drive more in the auto-oriented suburbs, but there's more infrastructure to maintain. Goods and services have greater distances to travel. And the houses and lots are bigger. All of the above promote more consumption.

With regard to greenhouse gases, the handiest data from New Geography's standpoint comes from Australia — specifically the study Consuming Australia, that forms the basis for the Australian Conservation Association’s Consumption Atlas, where you can type in a postal code and get a number for average carbon emissions in that locale. The emissions closely track wealth, according to the Atlas, and wealth is concentrated in dense cities in Australia (more so than the US). So the number tends to be higher in urban postal codes, and New Geography has made much of this finding, citing this data more than a dozen times in recent years. This calls out for further examination, because there's a lot less here than meets the eye.

Consuming Australia attempts to allocate total greenhouse gas emissions to individual Australians. That's tricky, because most greenhouse gases are generated by industry, agriculture, road-building, and other sources that are difficult to attribute to households. Much of the data used by the study is national, some is gathered at the state level, and some is regional.

Using economic models and consumption surveys, the authors apply this data locally. The study is intended to make individual Australians aware of how much carbon they produce when they go shopping or pop open a Foster's. 

Unfortunately, Consuming Australia does not appear to be an accurate tool for assigning greenhouse gases at the neighborhood level. To accomplish that, it is crucial to get vehicle miles traveled (VMT) figures, among other data, for those neighborhoods. VMT is not part of the Australian study.

The implications of this omission go beyond individual driving. How do you allocate, to individuals, greenhouse gases from road construction and maintenance, a "free good" that is disconnected from household expenditures, without measuring VMT? Emissions from the asphalt industry are huge, and they are, in this study, distributed across the board — when they should be connected to settlement patterns that actually require higher or lower use of asphalt.

I don't want to pick on this study, because the main conclusion has some validity: Higher incomes tend to be associated with higher carbon emissions — but there are important exceptions, and they seem to occur mostly in very liveable compact cities (see New York data in the graph "Country and cities CO2"). Moreover, the correlation between spending and greenhouse gases does not hold true when comparing countries that have different settlement patterns (see US emissions versus European countries and Japan).

Europe, for example, with denser cities and a similar standard of living to the US and Australia, has far lower carbon emissions. US emissions are 82 percent higher per capita than Germany's, and 207 percent higher than France's. If suburban development patterns reduced carbon emissions, then US, the most suburban nation on Earth, would be expected to generate less carbon than Europe, not significantly more as is the case.

Detailed studies in the US point to the reason. The Housing & Transportation Affordability Index, (H&T Index) by the Center for Neighborhood Technology in Chicago, has data on vehicle miles traveled and transportation carbon emissions for every census block and metro area in the US. Without exception, the metro areas look like the attached Portland map, which shows carbon emissions from transportation rising dramatically outside of inner cities.

Another map (Bay Area emissions) from the Metropolitan Transportation Commission shows greenhouse gas emissions from all transportation in the San Francisco Bay area. The emissions from the sprawling suburbs are triple those of the central cities. This study does not include added emissions from the building and maintenance of roads, parking lots, and far-flung infrastructure, or energy use in disconnected buildings.

Still another source is conservative economist Edward Glaeser of Harvard, who mapped carbon emissions for households in the Boston area, which, like the H&T Index maps, show a dramatic drop in carbon emissions as one moves from the suburbs toward the city.

A closer look at the first graph, by McKinsey & Co. and the World Resources Institute, dramatically illustrates two points. Not only are US emissions a lot higher than more urban developed nations, but also emissions for the US are triple that of America's densest city. Is the current brand of automobile-oriented suburbs greener? Impossible.

Getting back to Australia, it must be noted that the nation is in the midst of a hot political debate over a carbon tax, which has brought out factions that are making half-baked arguments. Although the authors of Consuming Australia defend their conclusion that the effects of wealth are greater than geography when calculating greenhouse gas emissions, they nevertheless strongly disagree with any conclusions that suburbs are inherently greener.

"We are aware that some commentators have used these findings to encourage unsustainable peri-urban developments, and we categorically reject their conclusions," Chuck Berger of the Australian Conservation Association told Planetizen. "Eco-footprints in suburban areas in Australia are lower than in the urban core in spite of, not because of, lower residential densities."

The real issue is not whether automobile-oriented development patterns lower carbon emissions — this claim cannot be taken seriously in view of the evidence — but how the suburbs can be made greener. Most research points toward land-use reform to make suburbs more walkable, mixed-use, and transit-friendly. Fortunately, these measures also improve quality of life and revitalize local economies. I certainly hope that New Geography can support those goals.

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