https://www.theguardian.com/environment/2023/oct/04/climate-scientist-faces-sack-for-refusing-to-fly-to-germany-from-solomon-islands-archipelago
Dr Gianluca Grimalda told by Kiel Institute for World Economy he must be at his desk on Monday after finishing fieldwork
!europe
Europa
That's common misinformation you've heard. Sure, the global footprint of cargo ships is very high. But if you look at the CO2 per ton-kilometer, even the dirty ships are 20-30x more efficient than brand new airplanes.
Ships emit a lot globally because they carry an insane amount of cargo around. There's just no way whatsoever to carry as much on planes.
But we're talking about passengers, not cargo, so the relevant numbers are CO2 per passenger-km.
Which changes the efficiency - because while you can cram people tightly for a 12h flight, you can't do that for a few weeks journey.
https://travelandclimate.org/transport-calculations
https://www.theguardian.com/travel/2006/dec/20/cruises.green
It should also be noted that, due to absurd economies of scale, international production can often still be more environmentally efficient than local production for some items, even if they have to be shipped halfway across the world.
IMO the main problem with cargo ships is that the bunker oil they use is super dirty (in terms of NOx, SOx, and particulate emissions), not that it's inefficient in terms of CO2 per ton-kilometer. (That said, there's still room for improvement on the latter, by using sails -- either the traditional kind or the newfangled computer-controlled kite sails.)