Sunday, June 01, 2008

What Is Your Area's Carbon Footprint?

Last week the Brookings Institution released a report on carbon footprints of the 100 largest metropolitan areas in the United States. Metropolitan areas have an important role to play in slowing global warming since density reduces energy use. Urban residents are more likely to have shorter driving distances, or may take public transportation, cycle, or walk. Denser housing, especially condos and apartment buildings, tend to reduce the energy needed for electricity and heating per unit.

Per capita footprints of metropolitan residents vary widely; the hundredth city has more than twice the footprint of the first. However, residents of metropolitan areas have smaller carbon footprints than the average American. The metropolitan areas with the smallest footprints are clustered on the West Coast. The largest carbon footprints are clustered in Ohio, Kentucky, Indiana, and Tennessee. I have posted the top ten and bottom ten at the end of this post; the full ranking is available here (pdf), and profiles of the 100 metropolitan areas are here (pdf). The footprints calculated for the study are not complete. They include only ground transportation and residential energy and exclude commercial energy and air travel.

The New York metropolitan area, the closest major city to where I live now, scored among the top ten. It emits 1.495 metric tons of carbon per capita, good for 4th overall. New York ranks so high primarily because of its reliance on public transit, which includes the city's subway and bus system as well as a commuter rail network that extends deep into upstate New York, New Jersey, and Connecticut. It produced the least carbon from highway transportation of any metropolitan area.

Despite New York's proximity to where I live, it does not provide a good approximation of the carbon footprint of Central Jersey. The Trenton-Ewing "metropolitan area" is probably closer to reality for my county. Trenton-Ewing, ranked 63rd, emits 2.660 metric tons of carbon per capita. While the Trenton-Ewing area produces less carbon for residential energy (ranked 21st), it ranked 91st in emissions from transportation as a result of emitting more carbon per capita from automobile use than any other metropolitan area. The lack of good local transportation alternatives and low-density development make for a large carbon footprint.

The metropolitan area where I lived for eight years, Washington, DC, ranks 89th and emits 3.115 metric tons of carbon per capita. It limits transportation emissions quite well; it ranked 20th for all transportation, and 10th for freight transportation. However, it ranks dead last in residential electricity use, which increases the overall footprint. I suspect this is a result of the region's reliance on coal to generate electricity. Coal is one of the dirtiest fuels for power generation; the Mid-Atlantic has plenty of coal to burn and plenty of places to burn it. The Baltimore area also fell low in the rankings.

The report details the limitations that cities face in reducing their carbon footprints and proposes federal policy changes that could help. Overall, there needs to be better regional planning, especially for transportation networks. The report advises that the federal government promote more public transit alternatives to cars and make freight transportation more energy-efficient. In particular it advises that the Department of Transportation become modally-neutral instead of its current policy of favoring highway construction. The report also recommends ways to reduce residential energy consumption through federal housing policy and full disclosure of energy costs in the process of buying a home. If you would like to delve into the details, read the full report.

I think the suggestions provide a sound starting point for reducing metropolitan-area carbon footprints. I especially hope that the federal government implements the suggested reforms to transportation policy. Modal neutrality is long overdue.

Best Ten Carbon Footprints

  1. Honolulu, HI (1.356 metric tons per capita)
  2. Los Angeles-Long Beach-Santa Ana, CA (1.413)
  3. Portland-Vancouver-Beaverton, OR-WA (1.446)
  4. New York-Northern New Jersey-Long Island, NY-NJ-PA (1.495)
  5. Boise City-Nampa, ID (1.507)
  6. Seattle-Tacoma-Bellevue, WA (1.556)
  7. San Jose-Sunnyvale-Santa Clara, CA (1.573)
  8. San Francisco-Oakland-Fremont, CA (1.585)
  9. El Paso, TX (1.613)
  10. San Diego-Carlsbad-San Marcos, CA (1.630)
Worst Ten Carbon Footprints
  1. Lexington-Fayette, KY (3.455 metric tons per capita)
  2. Indianapolis, IN (3.364)
  3. Cincinnati-Middletown, OH-KY-IN (3.281)
  4. Toledo, OH (3.240)
  5. Louisville, KY-IN (3.233)
  6. Nashville-Davidson--Murfreesboro, TN (3.222)
  7. St. Louis, MO-IL (3.217)
  8. Oklahoma City, OK (3.204)
  9. Harrisburg-Carlisle, PA (3.190)
  10. Knoxville, TN (3.134)