This might be a diversion of the thread, but I thought I should address this. This is a common criticism, and least its vibe is.
They're accused of being hypocritical, or gluttonous, etc. But it's unfair. You don't hear the people who object who refrain from doing this. I tried to be part of a rally regarding GHGs in my area. And both Green Party members and our opponents were wringing their hands, bemoaning the gas we burned to get to the rally.
But, no one gives two craps about the Green Party member who stayed home that day, worried about tailpipe emissions. No one counts them. No one cares what they think.
Now, if we intentionally modified our cars to roll coal and then showed up to the rally, that would be another thing. But it wasn't. The only way to get our political voice heard competitively is to burn oil as judiciously as we can. It's not a fair fight. The CEO of Exxon can take his Private Airliner to these meetings, but if I take an economy-class flight with nearly no luggage (to avoid weighing down the plane more than I needed to), I'm a hypocrit. And, somehow, the CEO of Exxon gets extra points in the debate if I even showed up ...