Particulates and SO4 are short-term acute pollutants. They are problems, but the problem is localised (shipping routes, ports), and settles out fairly quickly.
The scope is significant -- you can see shipping lanes simply by the SOx emissions, as the Nullschool Weather Visualiser shows, here, traffic between Indonesia and the Gulf of Aden is clearly visible:
But: CO2 remains resident in the atmosphere for centuries or millennia, affecting long-term climate. It's a vastly larger problem.
Moreover, particulates and SOx can be mitigated with improved fuel quality and stack scrubbers, at relatively low (though nonzero) costs. CO2 emissions are intrinsic to hydrocarbon combustion. We either have to stop burning anything with carbon in it, or switch to biomass (present-cycle carbon) rather than fossil-fuel based sources. Which is its own problem, though potentially tractable for shipping using various biomass wastestream sources.
The scope is significant -- you can see shipping lanes simply by the SOx emissions, as the Nullschool Weather Visualiser shows, here, traffic between Indonesia and the Gulf of Aden is clearly visible:
https://earth.nullschool.net/#2019/09/03/1800Z/chem/surface/...
But: CO2 remains resident in the atmosphere for centuries or millennia, affecting long-term climate. It's a vastly larger problem.
Moreover, particulates and SOx can be mitigated with improved fuel quality and stack scrubbers, at relatively low (though nonzero) costs. CO2 emissions are intrinsic to hydrocarbon combustion. We either have to stop burning anything with carbon in it, or switch to biomass (present-cycle carbon) rather than fossil-fuel based sources. Which is its own problem, though potentially tractable for shipping using various biomass wastestream sources.