Towards a Sustainable Food System: A Back-of-the-Envelope Approach

The US (and global) agricultural system, which depends heavily on fossil fuel-based energy and fertilizer inputs, is widely regarded as unsustainable, and is highly destructive to natural ecologies and biodiversity. Despite widespread interest in sustainable agriculture, the term is, in practice, poorly defined. This talk presents a back-of-the-envelope approach to the basic quantitative boundary conditions of the food system, as well as a brief history of how overdrawing land and nutrient stocks has represented a challenge to agricultural sustainability and productivity since time immemorial. The "Green Revolution" of the last century partially overcame these challenges to yield, by far, the most productive and efficient food system in history. However, the same long-term dynamic of overdrawing finite resources remains in play, and it cannot be solved at the whole systems scale by reverting to older methods of production (e.g. draught horse power, manure for fertilization), especially if food demand remains constant. Instead, I demonstrate that most of the revolution's productivity gains have been squandered, with up to 90% of agricultural produce effectively wasted as profoundly inefficient biofuels, overproduction of animal products, and direct wastage of edible food. A large-scale demand shift, especially if accompanied by supply-side shifts that reduce erosion and increase semi-natural land on farms, has the potential to free large amounts of agricultural land and largely balance the systemic resource input/output mismatch.