I have trouble believing that those giant CO2 spewing cargo ships are so small a factor.
It’s why the “buy local” movement wouldn’t really save much CO₂. Driving the trucks from the harbour to the consumers emits more, AIUI.
Yeah, that’s a good point. But I’ve always looked at the buy local movement as a way to fuck over billionaires.

I’m totally in favor of buying local! It preserves local culture, helps your neighbors, and deprives capital of a way to exploit people out of sight. The food is fresher, and having to cook with seasonal ingredients adds variety and gives fun challenges.

But it won’t prevent much carbon from entering the atmosphere.

Different farming practices use different techniques and tools and all have very different carbon output. That’s part of the equation of carbon production. Some farms are good at carbon sequestration and some are resource intensive.