There has been a lot of talk in recent years about concepts like “food miles,” “locavore eating,” “terroir,” and “Slow Food.” All of them boil down to a desire to re-think our increasingly globalized and industrialized food system and get back to bioregionally-appropriate fare, in order to both spare the emissions involved in packaging and transport, as well as diversify our diets to include indigenous plant and animal life.
While the theory behind concepts like food miles is solid, a recent study in the journal Landscape and Urban Planning by by UC Santa Barbara professor David Cleveland puts a number on the impact of growing vegetables at home: Every pound of produce grown at home spares two pounds of greenhouse gas emissions, compared to purchasing the same amount of produce in stores.
The study was based on theoretical models where lawn space was converted to vegetable production and some household waste products, like graywater and compost, were diverted to the garden instead of into larger systems of collection and management.
There were some caveats: One had to do with the management of compost systems. While home compost done right has a net positive climate impact compared to a landfill, improperly managed compost heaps can emit nitrous oxide and methane. Methane is a particularly potent greenhouse gas, with 86 times the climate impact of carbon dioxide. The key to managing compost responsibly is in keeping it aerobic—whether by turning, pitching or poking holes in it—because anaerobic compost will produce a heavier load of greenhouse gasses.
It may seem like a small thing in the face of trying to save our changing planet, but the amount of emissions spared is nothing to sniff at. It’s something to feel good about with every harvest of homegrown produce, and perhaps enough to convince the neighbors that even the smallest front-yard or backyard vegetable garden pays dividends beyond fresh food.
