But it is a very real question. I think it is Airplanes myself for 2 reasons. 1. Because they pollute at a high altitude (roughly 3 – 30 thousand feet) and, 2. because of an amazingly random accidental experiment after 9/11 that showed with all planes grounded our atmospheric temperature dropped a full degree. With Boats (ok large Ships) they burn something like warm asphalt, and that over water where the output can fall directly into what ever body on which they float. So essentially which is worse? High altitude kerosene or low altitude vaporized warm asphalt? I know – it makes me want to puke.
As a side note – i wish somebody would measure the net effects on global warming between Boats and Plane as opposed to co2 emissions which is awfully easy but not particularly insightful.
Go there and read. More next week.