More Edward Glaeser on Environmentally Friendly Development

I have previously written about Edward Glaeser, in the context of an article in the LA Times arguing that California should relax restrictions on development because households in California have a smaller carbon footprint than households in other areas of high growth. In this post at the Economix blog on the New York Times website, he makes an argument that we should support urban, rather than suburban, development.

In almost every metropolitan area, we found the central city residents emitted less carbon than the suburban counterparts. In New York and San Francisco, the average urban family emits more than two tons less carbon annually because it drives less. In Nashville, the city-suburb carbon gap due to driving is more than three tons. After all, density is the defining characteristic of cities. All that closeness means that people need to travel shorter distances, and that shows up clearly in the data.

While public transportation certainly uses much less energy, per rider, than driving, large carbon reductions are possible without any switch to buses or rails. Higher-density suburban areas, which are still entirely car-dependent, still involve a lot less travel than the really sprawling places. This fact offers some hope for greens eager to reduce carbon emissions, since it is a lot easier to imagine Americans driving shorter distances than giving up their cars.

But cars represent only one-third of the gap in carbon emissions between New Yorkers and their suburbanites. The gap in electricity usage between New York City and its suburbs is also about two tons. The gap in emissions from home heating is almost three tons. All told, we estimate a seven-ton difference in carbon emissions between the residents of Manhattan’s urban aeries and the good burghers of Westchester County. Living surrounded by concrete is actually pretty green. Living surrounded by trees is not.

Overall, I find this argument a great deal more convincing than I did the last one. We should shift toward higher density development. However, the issue I raised in my previous post remains, would changing our sources of energy provide a greater or similar benefit to changing our type of development? In the previous post, that referred to improving energy efficiency and renewable sources in other areas of the country to match California’s standards. In this case, would improving energy efficiency and renewable sources in, say, suburban Texas provide more benefit than relocating from Westchester County to New York City. From a policy point of view, this seems like the bigger question. That said, adopting the point of view that we must do everything we can to prevent climate change, clearly we should do both.

I do have a second quibble, though, especially with the last sentence quoted above, and the entire tenor of the post. Living surrounded by concrete is only more ‘green’ than living surrounded by trees given the existent types of development we have. There are all sorts of air quality and meteorological impacts to the lack of plant life in cities. Concrete and asphalt retain much more heat than countryside, to the point that Atlanta affects its own weather. Equally importantly, plant life is important to people’s psychological and emotional well-being. Rather than simply replacing actual forests with concrete jungles, we should try to make the concrete jungle a little more forested. There is more to being green than having a small carbon footprint. If we do decide that part of the solution to climate change is high-density development, we will need to invest considerable thought into minimizing the other environmental impacts of cities.

I don’t mean to say that Professor Glaeser would disagree with this point. I do, however, think that his articles may seek to make a rhetorical point that carries his argument too far.


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