Seriously Chipotle, if we're talking the production of harmful "greenhouse gasses", the black beans in your burrito bowl make the avocado seem Erf Friendly by comparison.
Just speaking from my own "carbon footprints" experience.
By the way, I went to a Rocco's Tacos in West Palm last month (free plug). I love how they wheel the avocado cart up to your table and prepare the guacomole dip while you watch. Definitely worth the life of a polar bear or two.