I was out a few weeks ago and fell into a political discussion with a guy I'd never met before. He was (isn't everyone?) to the left of where I stand, but he was good-natured and it was fun. At one stage he jokingly asked me if I worried about my carbon footprint. That was good for a few chuckles.
Anyway, I was thinking about this later and about another conversation I had with someone where I (jokingly) said that divorce was terrible for the environment. "All those people now living alone who used to live with at least one other".
Even though I was joking, I'm sure there's some truth in there somewhere. Maybe we as a society can use it. Rather than trying to guilt people into staying married for the sake of the children or because it's the right thing to do, maybe we could say, "Think about what will happen to your carbon footprint if you walk out on her (or him)".