I need some perspective on this "100-mile diet" thing.
When I worked in restaurants for 10 years, I saw that, particularly the fruit and vegetable markets are very inefficient. Things tend to be packed and re-packed, shipped and re-shipped, largely (it seemed to me) because growers don't care and the F+V markets are notoriously corrupt and hidebound - oh and you do have to get rid of bad fruit.
And it's that last one that bothers me. Occasionally, you would get a box of fruit (all F+V are often referred to as "fruit") that you know had come direct from the packer, say in California or Florida. This would be at the height of the season in the area the fruit was from. And I noticed that, although the fruit was very good, there was something of a Bell curve to it. Watching the behavior of people in the market, I figured that only at the height of the season did growers and packers stop their usual game of hiding bad fruit and threatening to leave the harvest unsold, respectively. They just got it to you. So there was much less picking over. But that also means the packers were okay with that because they did get boxes sent back. So that would imply that they were getting the fruit for lower cost.
And it's here that I get a little dubious about this "100 mile diet" thing. People have this idea that fruits and vegetables just come all year, in roughly the same condition. But obviously there are tremendous peaks of production at any given farm. And that means that all farms are exporters and that they must export FAST, and that they MUST produce far more than the local population needs or they could never stay in business. Any grower is dependent on a system of rapid and widespread distribution. In fact, this has been the basis of agriculture since the Middle Ages, has it not? The entire point of agriculture is to allow producers to specialize, thus saving person-hours, etc.
It seems to me that the very last system you want to interrupt is the food distribution system. And in a system that has such low profits it "must" employ illegal workers at illegally-low wages, transportation is a major cost. It's not as if these apple growers out here in Washington who produce all those perfectly uniform, not-so-great, apples wouldn't love for everyone to come out to Yakima or Winthrop and pick up their apples themselves. They could keep them on the trees longer, grow more interesting varieties, all that. But the truth is that that in a decent year it is a challenge for any apple grower to get his fruit off the trees fast enough at harvest, much less actually find consumers for the fruit.
And the idea that we are going to go back to small, multi-crop farms seems ridiculous when the trend has been the other way for centuries.
Isn't this all a question of efficiency? And why in the world pick on fruit and vegetable growers for THEIR carbon footprint. That seems crazy to me.
Finally, I'm just not sure that it actually saves that much greenhouse gases.