[Lewis Thomson (OP)]

Jeff says:

A recent guest on the show implied that rockets have a massive carbon footprint.  First, the dominant fuel for SpaceX rockets is liquid hydrogen and LOX.  Depending on the source of electricity used to liquefy the hydrogen and oxygen, these fuels when burned are carbon neutral. Second, SpaceX also uses 17,000 L of kerosene compared with 185,000 L for a single 747.
So the carbon footprint of a trip to orbit cannot be calculated as a linear equivalent of the number of Jumbo Jets of the rocket power output.