[m000z0rz]

IIRC, SpaceX is planning to generate all their methane using CO2 captured from the atmosphere as a test of the equipment that will do this on Mars.

[Symmetry]

Eventually, it won't be true for a while. Still, the carbon impact of launch one of these isn't that far off from sending a 747 around the world. Most of the fuel mass it's carrying is oxygen and methane is relatively carbon efficient as a fuel compared to bigger hydrocarbons.