That article is missing point. The point of eating local food is that you eat what's in season and what's available in your area. Obviously if you live in Canada you won't be able to find 'local' Avocados, but the idea is you would forfeit eating Avocados in favor of eating whatever is locally produced, instead of shipping those Avocados from Mexico.
What the article is asserting and what the science shows is that even if you have Avacados being grown literally next door the environmental impact of buying them locally is often higher than shipping them from abroad.
For example, the SGU podcast they link to [1] (around 55m:50s in) discusses that the net environmental impact (carbon emissions) of shipping beef to the UK from New Zealand is less than consuming UK beef in the UK. So if you're an environmentally conscious UK consumer you should be spending extra to buy NZ beef instead of buying locally produced beef.
This is because the carbon impact of the transportation generally hovers around 10%, which leaves the other 90% for actually producing the product "locally", and some locations on earth are vastly more efficient by every environmental metric in growing certain crops or raising certain livestock.
From the podcast: "An acre of land in Idaho can produce twice the amount of potatoes as an acre of land in Kansas".
Which leaves two reasons to buy locally.
Firstly you may be living in one of the places that's efficient at producing a given product, e.g. you'd buy local beef in New Zealand instead of importing it from the UK.
Secondly there are certain products that don't ship well, e.g. heirloom tomatoes. There you simply don't have the option of buying anything except local varieties.
Yes, but generally those will average out, and other than carbon emissions the environmental impact tends to get pretty well priced into the end product because it tends to be more land or resources that are required.
I put "carbon emissions" in parentheses there because the reason for this "buy local" fallacy to begin with is because people intuitively assume that it's the transportation of the good that makes all the difference, when the reality is that that's just 1/10 of the cost.
The environmental impact of the transportation is almost exclusively carbon emissions.
> other than carbon emissions the environmental impact tends to get pretty well priced into the end product because it tends to be more land or resources that are required.
No, most of the environmental impacts of agricultural productions besides carbon emissions are still externalities, usually time-shifted, that aren't priced into the product.