Ignoring the point that climate sensitivity wasn't in the parent comment, AFAIK, airplanes generate 0.16 kg/km, whereas trains are around 0.1 kg/km and container ships are at 0.016 kg/km. However, passenger ships and gas cars are at 0.25, diesel cars at 0.28 kg/km and rockets are over 1.0 kg/km, so it appears planes are in the middle, not really "one of the best ways" to worsen climate change.

Sure, through a simple analysis of CO2 kg/km, trains are better for the climate for long distance travel, but they are vastly slower (average time from LA to DC is over 80 hours), which has knock-on effects, e.g., sleeping at home averages 0.25 - 0.32 kg/night, whereas staying at a hotel averages 10-40 kg/night, eating at home averages 2.3 kg/meal vs. 3-8 kg/meal, etc.

What is it per passenger-mile, that's what you would have to compare to e.g. a car, bus, or train.