The environmental movement in the United States has historically been anti-city. Change is afoot, however, as cities across the globe, including many American ones, are taking aggressive measures to reduce their carbon contribution to climate change. If one breaks down the city, neighborhood by neighborhood, the highest-carbon-emitting households are found in the outer suburbs, while those with the smallest footprint are smack-dab in the center of cities. This is especially true in American cities where urban sprawl is most prevalent.
A recent Environmental Protection Agency study comparing four factors — drivable versus walkable location, traditional construction versus green building, single-family versus multifamily housing, and conventional versus hybrid automobiles — made clear that, while every factor counts, none counts nearly as much as walkability in reducing carbon output. In car-dependent areas of a city, transportation energy use consistently tops household energy use, frequently by almost two and a half times. As a result, the greenest house with a Prius in the suburbs loses out to the least green house in a walkable neighborhood. Although painful for a builder to admit, the greenest building, even though important, is overshadowed by location and transportation choices for reducing carbon impact.
Paris, France, a city with a lower-per-capita carbon footprint than any American city, has moved rapidly to reduce its auto dependence. It has, in recent years, created 25 miles of dedicated busways, introduced 20,000 shared “city bikes” in 1,450 locations, and committed to removing 55,000 parking places from the city every year for 20 years. Since these changes are happening in an old, built-out city with support from 80 percent of the inhabitants, we can certainly do more to implement improvements in the walkability, biking, and public transit of our city while making car mobility less convenient and getting automobiles to own up to more of their true cost.