I have read some Dutch research which showed tha tomatoes grown in Spain had significantly lower CO2 emissions than the same tomatoe grown in the Netherlands, including the transport to the market, which I think was in the Netherlands. I have the paper (in Dutch) lying around somewhere.
The main reason was that the Dutch heat and light their horticultural crop and the Spanish did neither (or much less). The Durch have significantly higher yield per sqm, which is necessary, as their infrastructure (greenhouses, land) is much more expensive. It is slowly changing, as the Dutch are building low energy greenhouses now, but I am not certain if it is fast enough. The greenhouses in place are relatively expensive infrastructure to replace and the profit margins are negligible at the moment.
From an environmental point of view it is tricky, as the Dutch use a lot less pesticides on their horticultural crop than the Spanish do. So it us not all obvious what is better or worse. Although I read recently that in total the Dutch use more pesticides than any other European growers, but I think that is on outside crops, not those in the greenhouse.
> Does that mean the 'buy locally' idea has little climate impact?
No, buy locally has a large climate impact - only not in the direction you think. Local uses much more energy than non-local.
Local has no environmental benefits whatsoever - only negatives.
The only thing it has going for it is some nebulous social benefits of knowing your farmer.
I avoid local because it means the produce was grown not in the climate where it grows best, but rather forced (i.e. lots of extra resources) to grow near me.
Even if it's in season doesn't mean your climate is the best place to grow it.
If it was the best place, then it would be competitive on the open market, and produce from your area would be the primary produce on the market - without any hokey social movements.
That's only true if you want to claim that the "best" place to grow $randomFruit cannot be more profitably used doing $randomThing. Downtown San Francisco could be the world best microclimate for tomatoes but it still probably wouldn't be worth using the land for that instead of an apartment.
The farmer pulling a turnip trailer thirty miles to the local Friday Farmer's market with an F350 dually can easily consume more energy and produce more CO2 per turnip than one shipped at industrial scale half round the world. The "last mile" can often be the least efficient.
Interesting.
Is that still the case if the true costs of greenhouse gasses emitted by transportation and refrigeration are accounted for?
Does that mean the 'buy locally' idea has little climate impact?
Also, to save my lazy, busy fingers from doing it myself, do you happen to know a good link to research on this subject?