Nature's best friend: the city

From Wired, here's a very informative map of per-capita carbon emissions in the United States. If you want total carbon emissions (not per capita), they have another. The maps are essentially inverted – the places that use the most amount of total energy are the most densely populated, yet they emit much less carbon per person. Even cities that we don't think of as very urban – like Los Angeles, Phoenix, and all cities in Texas – do very well in per-capita carbon emissions. In the original article, they show a close-up of the LA metro area, and it actually says that some parts have negative carbon emissions. I don't really understand how that's possible, but the point – that they have a carbon footprint about an order of magnitude smaller – is well taken.

There are a few reasons why cities are so much more efficient than other types of living. For one, people occupy smaller houses, and those houses are often stacked on top of each other, allowing more insulation, which reduces heating and cooling costs. Their transportation carbon footprint is much lower, since car ownership is less prevalent, and ground-based mass transit is remarkably energy efficient. This applies to all goods consumed in cities: since many distribution systems are based at least somewhat on a hub-and-spoke model, being in the "hub" allows goods to get to you much faster, using less energy. Furthermore (and this may account for the negative carbon emissions of the most densely-populated centers), the amount of nature that has to be destroyed is much lower, and many natural landscapes (forests, plains, etc.) act as carbon sinks, removing carbon from the atmosphere and turning it into oxygen.

Most of the time, efficiency in energy equates with efficiency in economics, as the system will use fewer inputs to achieve the same output. However, we'll never know, since the most polluting industries (transportation and energy production) have had their market signals removed by government policies and regulation, ensuring the perpetuation of the very anti-market status quo.