Loftwings and Demons

The problem with buying 'locally grown' food is that the bulk of the resources that go into growing food are used before that food ever gets shipped to consumers.  This is true for many other consumer goods as well.  This is not a solution to the environmental crisis agriculture is causing, and it is exactly the kind of not-solution that says solving the environmental crisis equates to consumers simply buying the right products, and the way those products are produced doesn't have to change at all.  But our entire system of animal and plant agriculture, not just factory farms, is built out of monocultures on private property that perpetuate ecocide and require vast amounts of oil inputs before ever leaving the farm.  Here's a graph that shows the source of emissions for different foods:

From this Our World in Data page.

This is not to say that there's no good reason to buy food locally, because there absolutely is, and that reason is that that food will generally taste way, way better than non-local food.  It's just usually not going to significantly reduce the emissions required to produce the food, because for most food produced today the bulk of those emissions are baked in before anything ever leaves the farm. So buying local only typically makes any difference at all if we're comparing it to the exact same foods bought non-locally, and even then the difference is often negligible.

This shows that it typically matters far more what we buy, if we're going to focus on buying things, than where we buy it from, because different foods take extremely different amounts of resources to produce.  

Why is our food system like this, when animals and plants in the natural world don't have this problem?  Part of it are the vast imputs to farms that depend on oil, but that is not the only significant factor.  The answer is, I think, that this system of industrialized monocultures that agriculture consists of is about as far from natural ecosystems as you can get.  All animals emit carbon via CO2 and methane while alive, and all plants and animals release it when they die.  But in natural ecosystems, the carbon of dead plants and animals is cycled into other plants and animals in an incredibly efficient recycling system, and this carbon is made available to a wide array of trees and other plant life capable of sequestering it.  In the system of modern agriculture, it ends up in landfills and our municipal waste systems. This is not something we see in the graph above, which only focuses on agricultural foods.  And there are no easy shortcuts for us to turn our incredibly wasteful system into something resembling the efficiency of a natural one.  But if we are to address the climate crisis, that is something we will need to do.