>Personal use of passenger vehicles accounts for a tiny fraction of transportation related CO2 emissions. The overwhelming majority comes from cargo ships and associated logistics.
while this might represent a small fraction of the global total emissions, the CO2 (and other harmful particles) produced by cars is much more detrimental to human health since it will be concentrated in the cities and near humans live.
The cargo emissions should be less harmful as there are not many people living in the oceans and algae effect should also be considered as it produces most of the oxygen we breath.
This is correct. If we ignore catastrophic climate change, the next worst thing is being directly exposed to personal transportation pollutants - amongst which CO2 is pretty benign but there is far worse stuff.
Living next to major roads or highways significantly reduces life expectancy.
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.
But at this point we need to prioritize, and climate change is arguably becoming more important than direct exposure to personal transportation pollutants.
while this might represent a small fraction of the global total emissions, the CO2 (and other harmful particles) produced by cars is much more detrimental to human health since it will be concentrated in the cities and near humans live.
The cargo emissions should be less harmful as there are not many people living in the oceans and algae effect should also be considered as it produces most of the oxygen we breath.