> If you want to attack CO2 costs, the primary costs are in the last mile.

If you want to attack CO2 costs, 90% of lamb's CO2 production occurs on the farm. Only 10% is from processing, distribution, retail, cooking, and waste disposal [1].

Let's charitably assume 1/3 of the post-farm CO2 emissions are from distribution and half of those could be saved by producing closer to the point of consumption.

So farm production only needs to be 1.8% (=(10/3/2)/90) more efficient in NZ for it to be net beneficial.

Presumably NZ is particularly efficient for lamb, otherwise it wouldn't be such a major export.

[1] To pick one reasonably creditble data source, see: https://en.wikipedia.org/wiki/Environmental_impact_of_meat_p... which ends with this graph: https://s3-us-west-2.amazonaws.com/webcitation/419e58a77a34f...

While I could believe that this is true, I would love to see some evidence to back up this claim. You would also need to account for the entirety of emissions, including, as a previous commenter said, other emissions involved in the supply chain.

It's not true sadly. http://www.worldshipping.org/industry-issues/environment/air...

If you go with a to of lamb for simplicity thats 10g/km. It's about 10km so 100,000g. The truck is like, let's go on the high end 100g/km and what, 100km? That's still only 10kg of co2. Unless of course I'm missing something.

The chart assumes you are moving 1 ton of material, so its 20kg of co2 to ship 1 ton of lamb 100km.

The answer is, as usual, 'it depends'. There are journals full of people modeling things like this. What is sure though, is that the claim 'local is always better' is not true. But it's easy to attack absolutes because they're almost always wrong.

Do you have any data to back this up? How does the NZ lamb get to the airport? And how does it get from the airport to the grocery store?

I think the parent comment is referencing the huge economies of scale you get on shipping things in bulk with respect to CO2 emissions. If you have 1,000 legs of lamb in a shipping container, the per-leg CO2 cost is low in comparison to one leg of lamb in a car, even if the distances are very different. A heavy truck gets maybe 6mpg compared to your car getting 25, but if the truck is carrying 1000x more items, the truck would have to go ~250 times farther to break even.

I'm not sure how it breaks out for air cargo (probably not great), but ocean and rail are both more efficient than trucks.

The problem is that's only amortizing on side of the equation. If you were to pick up that leg of lamb and a dozen other things on the way home from work then the additional CO2 cost from the lamb itself is negligible.

It's like saying cars produce less emissions than bikes by including the manufacturing costs of the bike but not the car.

Sure, it also depends what kind of car you're driving, how much traffic there is, how far you are from the grocery store, etc. etc. The original parent point I was trying to clarify is that transportation impact on the environment for most food products is low on the list of things we should be worrying about.

> It also costs less in CO2 costs to ship that lamb from NZ to a supermarket than to truck it in from a local farm to your fancy organic farmer's market.

How does the lamb get from the port to the grocery store? Is the port not roughly equidistant from the point of sale as the local farm? How is the “fancy organic farmers market” less efficient to ship to in the last mile before the point of sale?

Well that all depends on the exact numbers, doesn't it? But someone going to the farmers market twice as often as they'd need to go to the supermarket (because that produce doesn't last as long, although that mostly because of less efficient processing methods in small farms) is already almost surely polluting more than the person going to the supermarket.

That's not even mentioning the savings that can be had from home delivery. Although I had a local organic pig farmer deliver meat at home just yesterday, so that's not an advantage exclusive to large players (provided he has enough customers to do multiple drops on one tour - I should've asked him, come to think of it).

Meat (aside from fresh fish) is rarely flown.

That’s not really the point. Unless you go grocery shopping at the (air)port something else brings the goods to your store.

So:

CO2 for meat from NZ: Shipping + last mile

CO2 for locally produced meat: last mile

How is meat from NZ producing less CO2 than locally produced?

You're using one (18-wheeler) truck for all of the different kinds of food for the last mile in terms of distribution center-to-supermarket, but one (pickup) truck each for the different sources for the farm-to-farmer's market. Not to mention that the distribution center is likely closer than the farms.

But food doesn't grow in distribution centers. At some point you have to transport the food out of the farm. That would result in the following chains (simplified):

Local: Farm -(1)-> Farmer's market -(4)-> Consumer's home

National: Farm -(1)-> Distribution center -(3)-> Supermarket -(4)-> Consumer's home

International: Farm -(1)-> Harbor/Distribution center of producing country -(2)-> Harbor/Distribution center of consuming country -(3)-> Supermarket -(4)-> Consumer's home

Where (1) is the farmer's pickup truck, (2) is a massive high-seas-capable container vessel, (3) is the 18-wheeler and (4) is the consumer's audi.

Yes, (2) and (3) may be vastly more efficient in CO2 per transported item - but it doesn't change the fact that they happen in addition to (1) and (4).

That's not the case. When you talk about large-scale farming, the (1) in the latter chains are actually (3).

I would note it's frequently an 18-wheeler from the farm to a distribution center as well.