The carbon footprint of the average San Diegan -- including residential energy use and transportation -- is larger than that of the average resident of Los Angeles, CPI found in a review of available data. 

In recent years, Los Angeles has become a world leader in policy innovation to reduce energy use and fight climate change. San Diego lags behind Los Angeles in adopting green policies and in most Earth-friendly indicators, especially vehicle miles travel to per capita and use of renewable sources of energy.

On Earth Day 2009, CPI released a policy brief comparing key performance indicators and policy innovations in the two metropolitan regions.