"15 biggest ships" - good headline, is false
The headline was based on a prediction that in the near future the few biggest ships might emit more sulphur dioxide than all the cars in the world.
Because they burn bunker fuel, which at the time had a very high sulphur content.
It never considered any other pollutants or emissions.
Bunker fuel now has a much lower sulphur content (though still much higher than road fuels) - which was what the original prediction was trying to achieve.
In other words, the headline was utter tripe.