Most of us would think that taking the train is definitely greener than flying but in fact it isn’t. U.C. Berkeley discovered that taking the train/light rail uses up much more energy and produces more greenhouse gases than flying because the train uses more resources overall. Here is the article: www.fastcompany.com/blog/ariel-schwartz/sustainability/
train-travel-greener-flying-maybe-not . Hopefully, it does not take too long for trains and light rails to be as green as airplanes.

I actually was on a plane once when the pilot mentioned that our airline travels that day used a certain amount of fuel. While I forget the numbers, I remember that it was far more than driving- about 100 mpg or so perhaps. Of course when we fly, we travel farther distances, and so our GHG impact gets high, but it is a relief to know that planes are more efficient than cars...