We didn't used to know that flying's environmental downsides are so huge--but now we do. Will flying eventually become like driving a Hummer, a mode reserved for the unevolved? Just how bad is it? What fixes are in sight?
How big is the problem? Take all the West's greenhouse gas emissions--from industry, power plants, cars, agriculture, etc--and flying's portion works out to 10 percent. That's a startlingly high number. It got so big in part because planes release their CO2, water vapor, soot, and nitrous oxide into the upper atmosphere, which multiplies their ill effects. The average American generates 19 tons of carbon per year, but a single coast-to-coast round trip weighs in at 2-3 tons. What's to be done?