"…For many people reading this, air travel is their most serious environmental sin. One round-trip flight from New York to Europe or to San Francisco creates a warming effect equivalent to 2 or 3 tons of carbon dioxide per person. The average American generates about 19 tons of carbon dioxide a year; the average European, 10. So if you take five long flights a year, they may well account for three-quarters of the emissions you create. “For many people in New York City, who don’t drive much and live in apartments, this is probably going to be by far the largest part of their carbon footprint,” says Anja Kollmuss, a Zurich-based environmental consultant.…"