I’m reading, really listening to, Walkable Cities: How Downtown Can Save America, One Step at a Time. This 2012 book by Jeff Speck got some play when it first came out.  By “some play” I mean it was public radio popular.

Speck, who read the book for audio himself, reviews what researchers say works and doesn’t work in encouraging density and why density is a good thing for people and the planet.  Lots of  interesting stuff, but something that made me scratch my head and say “hmmm” was about a map that upends the assumption that cities are not green in comparison to less dense places.

Enter the 2002  Gurney-Vulcan map of US carbon emissions, in its original form and then recalculated to show per capita emissions.  (If you love the Big Block of Cheese episode of The West Wing with the Cartographers for Social Equality you’ll understand my excitement.)

Here’s the original emissions map-

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Researchers now have a better view of where carbon dioxide is being emitted thanks to Vulcan, a research project led by Kevin Gurney, an assistant professor at Purdue University. This map shows where CO2 is being emitted in the continental United States in 10-kilometer grids, and combines data from sources including factories, automobiles on highways and power plants. The map offers more than 100 times the detail of previous inventories of carbon dioxide. The image displays metric tons of carbon per year per grid in a logarithmic base-10 scale. (Purdue News Service image/Kevin Gurney)

As expected, large cities look red hot (opens jpg see page with link here).  Neither Speck, nor I, have any problem with this.  It’s a great representation of scrupulously collected data.  But it uses the wrong metric if you are asking “Where should I live to have the least damaging carbon footprint?”

The better illustration is the per capita map, also a Gurney-Vulcan product, shown below and found here (jpg, see page with link here).

Here the hot spots have flipped, simply because it just takes less fossil fuel per person to keep a city running than it does to have people scattered throughout rural counties.   Draw your own conclusions about where you should live, but don’t have too many regrets about not chucking it all in to become an organic farmer.

newvulcan