Economists Ed Glaeser and Matthew Kahn have written a new paper estimating the differences in carbon emissions across different metropolitan areas.
Using a hypothetial household with 2.62 members and $62,000 in average yearly earnings, they attempt to calculate how much carbon dioxide this household would emit in a given metropolitan area. They estimate household emissions from driving, public transportation, home heating and electricity (which includes air conditioning), and they factor in the relative cleanness of the region's electricity supply.
Their findings are not all that surpising:
- "Per capita emissions generally are lowest in Western metropolitan areas and highest in Southern ones. Metropolitan areas in the Northeast and Midwest fall in between these two extremes."
- "All told, if the social cost of one ton of carbon dioxide emissions is $43, then the annual environmental damage associated with an additional home in greater Houston is more than $500 greater than the damage for a new home in greater San Francisco."
Car-dependence obviously plays a large role, but often not as large as electricity consumption: The typical Houston MA household emits 3,000 more pounds of CO2 per year from driving than does the typical San Francisco household. But the typical Houston household emits 23,000 more pounds per year than the SF household due to extra electricity use. As we all know, air conditioning is expensive.
Their tentative conclusion is that perhaps we should make it easier for households to move from Texas to California, rather than vice versa:
This work is far too preliminary to be a sound basis for particular policies. However, it does emphasize the contradictions of current American land-use policies. Local land-use restrictions cannot stop development in the nation as a whole. They simply have the ability to move development from one area to another. Our current land-use restrictions tend to stop development in those areas, like California, that are environmentally friendly and to encourage it in areas, like Texas, where households produce more carbon dioxide. Within metropolitan areas, land use restrictions often push development out towards the urban fringe where energy use is highest. Our results do suggest that it makes sense to look for policies that would encourage building in more enviornmentally friendly cities and discourage it in areas that have the greatest carbon dioxide emissions.
