"Hindenburg made 17 round trips across the Atlantic in 1936 — its first and only full year of service — with ten trips to the United States and seven to Brazil."
At least the ships release other chemicals in their emissions that decrease solar warming.
As we ramp down fossils we this kind of thing would enable eg international agreements to limit and progressively lower shipping sector co2 credits over time.
We need to do this for all co2 emitter sectors since all the slices of the pie are fairly small so focusing on eg top-3 doesn't solve the problem.