Big Cities Helping Smaller Ones Pollute

Courtesy of their large populations, big cities like New York and Chicago are the worst polluters in the country. But the story looks different when you change perspective: A person who lives in New York puts out less than one half of the carbon dioxide emitted by someone living in a smaller city like Indianapolis.

This poses a dilemma for those trying to control climate change in the U.S., say Ed Glaeser of Harvard and Matthew Kahn of UCLA. The problem lies partly in the area of land control. The following chart plots the relationship between emissions and regulation in major metropolitan areas across the country:

A negative number on The Wharton Regulation Index means that a city has relatively lax development regulations, while a positive number means a city has tighter land-use controls. The chart implies that cities with tighter controls, which tend to be larger ones, also emit less pollutants per person.

But this can have a counterproductive effect. In past work, Glaeser argued that the rise of the Sunbelt since the 1980's didn't have much to do with the temperature but was driven by lax land-use regulation. So the restrictions on development in cities like Chicago, New York, and Los Angeles, while keeping per-capita emissions low, may be pushing pollution-causing activities to more laissez faire cities.

Write Glaeser and Kahn:

...current land use restrictions may be doing exactly the opposite of what a climate change activist may have hoped. Those restrictions, often implemented for local environmental reasons (such as to preserve open space or reduce neighborhood traffic), seem to push new development towards the least environmentally friendly urban areas.