Carbon cost of cities

There’s an interesting post at the NYT’s economics blog about the environmental cost of living in a city:

In almost every metropolitan area, we found the central city residents emitted less carbon than the suburban counterparts.

cars represent … one-third of the gap in carbon emissions between New Yorkers and their suburbanites. The gap in electricity usage [is] about two tons. The gap in emissions from home heating is almost three tons [of a seven ton total].

The decreased carbon cost of transport and heating in cities is predictable, but there are still questions remaining here.

I’d like to know more about the carbon costs of construction in cities but that’s likely to be a small part of the lifetime carbon cost of a building. I’d also like to know about the cost of having concentrated emissions: in a city the emissions per capita may be lower, but the emissions per hectare are far higher. If the effects of pollutants are non-linear then the environmental cost of cities may still be higher.

Finally, as the BBC points out, the comparison depends on where you live. Moving from suburban Chicago to the Bay area may decrease your personal carbon emissions, but moving from rural Sichuan to Beijing probably doesn’t. Urbanisation is correlated with industrialisation and industrialisation massively increases our environmental impact.

I don’t mean to suggest that we should deny poor nations the opportunity to industrialise: I only mean to point out that this result isn’t, by itself, a sufficient reason to promote further urbanisation across the globe (although it may be a necessary condition of such promotion).

Update: Ed Glaeser’s article has some of the numbers.

  • “I’d also like to know about the cost of having concentrated emissions: in a city the emissions per capita may be lower, but the emissions per hectare are far higher. If the effects of pollutants are non-linear then the environmental cost of cities may still be higher”

    Sorry I’m not sure what you are saying. Are you saying that the location of the emissions also matters – not just the per capita size of emissions?

    The way I see it the author is putting forward two extreme examples – put everyone in a city, or spread everyone over the country. If we put everyone over the city total emissions will be lower (although as you state there are indirect issues that aren’t addressed!). However, the location of these emissions is more concentrated.

    Are you saying the concentration matters in the above quote – or is there something else at work here?

  • I’m just saying the concentration might matter. If you have brainy ideas about what might be at work I’m keen to hear them 😉

  • No no thats cool – I just wasn’t quite sure what the “non-linearity” you mentioned was. The only thing I could think of was concentration – and I was just wondering if you had any other hip idea in mind

  • Hip??? I’m an economist, Matt!

    I just meant that, if the environmental damage function is non-linear in concentration, then total damage isn’t necessarily lower when you decrease emissions but concentrate them more.

  • I get that rauparaha – but in the post you just said that the impact could be non-linear. Now, I assumed that you were saying non-linear in concentration – but since you didn’t say that I was wondering if you actually had other types of non-linearities in mind as well.

    When I read the paragraph I felt it went: example + statement. The statement was more general than the example – so I was wondering if there was some other examples you had in mind when making that statement.