The per-ton CO2 emissions of those boats is still much, much lower than by truck or rail. Large ships are insanely efficient at moving cargo; that's why it's so economical to transport stuff across the planet.
Ship fuel (also called bunker fuel) is the dirties form of fuel there is and goes way beyond CO2 emissions. It is heavily contaminated and because of incomplete combustion it contribute heavily to pollution in water, atmosphere, and coast cities. The environmental impacts of heavy fuel oil spills also converts the ships into mobile nature disasters. The costs from oil spills generally spills over to society and people who live near the cost, rather than being carried by the shipping company. Collecting the real cost of that risk should be part of the product price when importing goods.
Tariffs are fungible, so the same tariffs could be used for the purpose of protectionism, geo-political stability, CO2 emissions in transportation, CO2 emissions in production, oil spill insurance costs, air/water pollution, regulative differences in worker rights, or differences in product safety. It can make the market competition more fair or unfair, and depending on what goals one have the definition of fair and unfair will likely change. People who lean both left and right can find arguments both in favor and against, likely at the same time given the fungible nature of tariffs.
Thus if one want to look at it on the bright side, pick the benefits of the political goals that talks to you.
Not arguing that the carbon tax is legit. It hasn't been proven yet that it isn't just a way to collect money while pretending to do something about the environment.
We should maybe just reconsider in general what kind of thing is economically viable
The real concern isn't that consumerism is threaten, as you seem to indicate that could be a good thing in fact.
I consider the U.S slowly becoming 19th century China.
I would like to remain positive but it might even be worse.
Globalisation, the U.S economy has been relying on developing countries to provide raw and finished produce. Not only de-industrialized, the population suffers from some superiority complex that makes it even hard to accept it may have to learn how to work and make stuff. Betting on AI to solve the universe, a migration to Mars.
Orders of magnitude more potent Pharmaceuticals. fantanyl is a hundred times more potent than Opium, a hundred times cheaper, and far easier to smuggle and conceal.
The U.S got to wake up, not just reconsider its consumerism culture.