This morning's newspaper features an Associated Press article about a Brookings Institution ranking of the 100 largest US cities, based on per capita carbon emissions. The worst of the bunch is said to be Lexington, KY, with 3.46 tons per person as of 2005.

My first reaction was total dismay. The article, the headline, and the accompanying chart all use the term "carbon footprint", and if we could get the average carbon footprint per US citizen down to 3.46 tons, we'd be in pretty good shape. The actual carbon footprint for an average US resident is on the order of 20 tons.

What the Brookings ranking is really based on is not carbon footprint, but only emissions from personal transportation and home heating. The article says this is "about half of all carbon dioxide emissions", but that's grossly incorrect. What it is about half of is individual (non-corporate) direct emissions. Indirect emissions such as those resulting from generation of electricity, or product manufacture and transportation, or food production, or waste disposal, or water consumption, or air travel are simply not included. And, as your local sustainability coordinator can tell you, indirect emissions far exceed direct emissions on most campuses (and for most individuals).

Still, the Brookings ranking has the potential to be useful. First, it points out that different people, living in different US cities, contribute differently to global warming. In contrast to a Lexington resident's 3.46 tons of carbon, someone living in Portland, OR or New York City emits no more than 1.5 tons -- less than half as much. Tell the average American (s)he has to give up all modern conveniences, and the response will hardly be enthusiastic. Tell them they should live more like someone in Portland, and the perceived threat level is far less. It's imaginable. It may even be attractive.

Additionally, the ranking does have the advantage of focusing attention on the two behaviors which most of us have the greatest potential to affect. Home heating/cooling efficiency and personal transportation habits are generally considered low-hanging fruit. And at today's energy costs, they're areas where an investment in conservation turns into bottom-line savings both quickly and clearly.

So maybe a little misinformation isn't all that terrible. Maybe I shouldn't write that correcting letter to the editor. Maybe "wrong, because ..." is better expressed as "right, and also ...". And maybe I should let a little time pass for the useful information to sink in, before getting to the "and also" part.