Housing and automobiles in the United States generate almost 40% of the nation’s carbon dioxide emissions. Emissions vary with an area’s population density and weather patterns.  These in turn affect automotive and transit use, home heating, air conditioning and electricity usage.

A 2008 policy brief by the Harvard Kennedy School’s Rappaport Institute and Taubman Center, “The Greenness of Cities: Carbon Dioxide Emissions and Urban Development,” seeks to quantify carbon dioxide emissions across different metropolitan and suburban areas in the United States.

The researchers finds that:

• Older and denser cities generally have significantly lower per-capita emissions than suburban areas in the same regions.
• The city-suburb gap is particularly large in older areas, such as New York.
• The lowest emissions areas are generally in western metropolitan areas, a consequence of their milder climate; the highest emissions areas are in southern areas of the United States, where development is spread out and air conditioning use is high.
• If the social cost of one ton of carbon dioxide emissions is $43, the annual environmental damage associated with an additional home in Greater Houston would be more than $500 greater than a corresponding home in Greater San Francisco.
• Current land-use regulations often push new development away from areas with low per-capita emissions and toward those with higher emissions.

Based on the policy brief, several approaches are possible to reduce carbon-dioxide emissions from the nation’s housing and automotive sectors. First, land-use controls should be adjusted to favor development in areas with low per-capita emissions. Second, a carbon tax would encourage people to internalize the social costs of their actions.

Tags: carbon, emissions, greenhouse gases, mass transit, cars, driving

By Leighton W. Klein | February 9, 2010