Planes? A bit of quick searching backs up what I thought -- ships are way less carbon-intensive than planes, though, to my surprise, less efficient than rail:

Planes? A bit of quick searching backs up what I thought -- ships are way less carbon-intensive than planes, though, to my surprise, less efficient than rail: http://carbonfund.org/how-we-calculate http://carbonfund.org/how-we-calculate And while I'm all for regulation, I'm basically pessimistic. Then again, overpopulation and nuclear escalation turned out less bad than I expected, so what do I know?