" A typical carbon map, such as that produced in 2002 by the Vulcan Project at Purdue University, sends a very clear signal: countryside good, cities bad.

For a long time, these were the only maps of this type, and there is certainly a logic in looking at pollution from a location-by-location perspective. But this logic was based on an unconsidered assumption, which is that the most meaningful way to measure carbon is by the square mile. It isn't.

The best way to measure carbon is per person. "

― , Walkable City: How Downtown Can Save America, One Step at a Time