Earlier quoted context omitted.
Ignoring all the other problems, like car crashes, urban land-use, infrastructure spending to support them, etc, their emissions alone should be a clear moral issue when talking about cars. When the alternatives (walking, public transit, and bicycling) are orders of magnitude more efficient, it's absolutely a moral issue.
From the math I've seen, bicycling is 1 order of magnitude lower CO2 emission than driving. Here is one source https://ecf.com/news-and-events/news/how-much-co2-does-cycli... I was surprised it wasn't a bigger difference myself. It also appears buses are in the 1 order of magnitude range: http://www.dnrec.delaware.gov/dwhs/info/Pages/OzonePublicTra... , https://www.citylab.com/transportation/2012/11/can-we-please...
Re: Great Divide in How Americans Commute to Work
#201I don't trust that this calculation went into sufficient depth. People who drive cars still eat food.