The Larger the City, the More it Pollutes, Right?

As we've previously written, researchers now know that cities obey some fascinating scaling relationships. The larger they grow in population, the more patents, infrastructure, crime and economic output cities produce, each according to its own exponential equation. When a city doubles in size, for instance, it more than doubles its GDP.

Until now, though, the relationship between population and pollution has been less clear. Larger cities must produce way more of it, right? Beijing, with its 20 million people, seems perpetually steeped in the kind of smog that's visible from space. And yet, larger cities are also supposed to have all kinds of energy-efficiency benefits, and 8 million New Yorkers can't possibly drive as much as 8 million people who live just about anywhere else in America.