From time to time, I'm invited to visit our local ag/tech college, which trains quite a number of students to enter the food service industry at levels where you never have to ask whether someone wants fries with that. Program faculty, of course, cover all the material about industry standards and standardized procedures and more-or-less standard approaches to management. But they've kind enough to ask me in to speak about sustainability considerations, and I really enjoy interacting with students who learn (and think, and create) in hands-on mode.
The first challenge, of course, is getting students whose primary focus is on enhancing their immediate employability to care, or even think, about anything that seems abstract, distant, far in the future. So that's not where I start. I start with freshness of ingredients. And reduced losses to spoilage. And better taste with less salt. Greater visual appeal. Enhanced perceived quality due to the menu being manifestly in synch with local seasons (who in the northeast USA wants baked butternut squash mid-summer, or cucumber/dill salad mid-winter?). Flavorful foods which satisfy customers, even at portion sizes some will initially think on the small side (less post-consumer waste). Fewer empty calories. More ability to manage quality risk (I point out recent large-scale food recalls) and cost risk (due to local supply agreements directly negotiated). I even point out the potential marketing advantage of being able to identify local suppliers -- sometimes even introduce them to the clientele.
So far, pretty much every student has gotten intrigued with at least some of these possibilities, which gives me an opening. It doesn't inherently sell them on purchasing, preparing and presenting food which is produced more sustainably than the American standard, but it moves the concept at least part of the way from "burden" to "opportunity". The possibility is created that they no longer have to compromise their aspirations in order to save the world. And I want to create that possibility in their minds before I even mention the whole world-saving agenda item.
Without getting heavy into the math, what I then communicate is that purchasing local, sustainably-produced food can help the biosphere by lowering demand for (use of) energy, fertilizer, pesticides, antibiotics, water and arable land; by emitting fewer greenhouse gases; by slowing the development of drug-resistant bacteria; by increasing local agricultural employment (it is, after all, an ag/tech college); by increasing local agricultural earnings/wages; by channeling business to local food processors; and by decreasing agricultural runoffs of topsoil, nitrates, endocrine disruptors, petroleum and other water pollutants.
While a century ago everyone around here sourced virtually 100% of their food locally (short growing season notwithstanding), I don't ask today's students to try to imagine that particular possibility. But I do ask them to imagine sourcing 60-80% of the calories they serve regionally, and I emphasize the practicability of that by telling them about nearby families, restaurants, and college dining halls which have achieved that level and higher.
What I'm really doing, of course, is trying to broaden the scope of their consideration during decision-making -- trying to extend it from an isolated purchase transaction to a purchase decision as the determinant of an entire production process, and from a single point in time to a future that extends across generations. In a very practical sense, that's what the whole "sustainability" thing is all about. And these are very practical kids.