[ZeroGravitas]

I strongly doubt that local food production would be less carbon intense. The reason for producing food in far off, but often sunny places is generally about accessing the free solar energy they have as well as higher efficiency because they can supply the whole globe year round, rather than one nation on a weather dependant cycle.

Shipping isn't particularly polluting by it's nature. Currently we allow people to burn some really dirty fuels in ships on the basis that it won't directly affect too many local voters and the fossil fuel industry needs to do something with the stuff they can't burn near people, but it would be relatively easy to regulate and is generally tightening up over time.

Moving to clean ammonia or hydrogen engines is also very doable.

Carbon taxes are often a talking point for politicians that don't actually want to do anything but many of your ideas could be better implemented as carbon fees and/or tariffs so that it will optimize for greenhouse gasses directly, not for what people think is the carbon cost of something.