Passenger vehicle exhaust is the primary contributor to central NJ's carbon footprint, and to reduce it will not be easy, considering that so much of our current culture is geared around building more sprawl. Come to the Planning Board meeting Wednesday to see how a developer can subvert the good intentions of a planned mixed-use neighborhood, which should mitigate car-only development, but only if parking is actually shared between the various uses in the development.
The key element is congestion, since it's unlikely we'll come to accept a toll-based road system, congestion pricing or pay-by-miles-driven taxes. Congestion is simply standing in line, or viewed differently, paying with personal time spent, and to get carbon reduction we'll have to accept it as a long term condition that at least has the advantage of treating all road users equally.
Except cyclists and walkers, of course, who can avoid congestion by using nonpolluting means for short trips, which make up 40% of all trips - a huge "reserve" road capacity, since it is easy to substitute short trips w bike/walk trips. But only If the roads allow it, which means road diets and other engineering changes that cost pretty much nothing to implement (some paint).
The social thing stands in the way of cultural acceptance of cycling and walking - supposed bikelash, seeing "those" others as others, calling "those" others arrogant, scofflaws or losers, etc. Here's a link to an 11-yr-old cyclist's views of the issue, as spoken at a road diet public meeting.
http://laist.com/2015/09/16/this_kid_is_awesome.phpJerry
also
http://wwbpa.org/2015/02/bicyclists-arrogance-explored/