A C Zoom

Union of Concerned Scientists - Getting There Greener

The one somewhat surprising item is that traveling first class or even economy-plus in airplanes is more damaging to the environment than coach-class. Of course, seems logical after-the-fact.
Since I cannot afford first-class air travel anyway, this specific green behavior is not a problem at all!

Airplanes have the worst impact on the environment. But air-travel is essential, so it is good to know that at least by traveling economy, one can reduce the impact on the environment.

In order of traveling long-distances with the least impact - motor-coaches - buses are best, then depending on number of people traveling, a efficient fully-filled car is good too.