According to a report released by the Brookings Institution, Los Angeles is the most carbon efficient major city in the country(besides Honoulu). And although it may seem suprising that, in a vacuum, this car obsessed, air conditioning using, sprawling, coal powered Ecology of Fear could be so green, it actually makes quite a bit of sense.

For one, Los Angeles is reasonably dense. Because the LA basin itself is hemmed in by the Hollywood Hills and the Ocean, a huge number of people live in a rather smallish area. Even the San Fernando Valley, the image of horrible sprawl, is surrounded by hills that retard further development. Secondly, lots of West coast areas did well because of their temperate climates which require less heating. Heating, because it raises temperatures from very cold to bearable requires a lot more energy than air conditioning, which lowers temepratures from very hot to bearable. (The actual degree change, and thus energy expended, is much less).  

Although there are some caveats - the survey used statewide averages for carbon emitted by power sources and it didn't include far-flung LA suburbs like Riverisde and San Bernadino counties - it still shows that there's something about the West coast combination of density and temperate weather that allows for relatively green living arrangments.