From food miles to buying seasonal and reducing meat consumption, here's the real environmental impact of sustainable food choices.
woman shopping at a farmer's market
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When switching to an environmentally sustainable diet, one of the first things people tend to do is buy more locally produced food. But while there are many good reasons to purchase from local farmers—supporting the local economy; getting riper, tastier produce; encouraging seasonal eating—there are some nuances that call into question how green eating local really is. Here are some factors to consider.

1. Food miles matter less than how food is grown.

Food miles, or the distance food travels from where it's grown to where it's sold, is definitely a factor in determining its carbon footprint. But it has much less of an impact than many people realize. A life-cycle analysis in the journal Environmental Science & Technology determined that, on average, 11% of food's greenhouse gas emissions come from transportation, while 83% of emissions come from growing, raising (in the case of animal protein) and processing the food.  

2. Avoiding synthetic fertilizer is important.

Rather than focusing on where food is grown, the bigger question may be how it is grown. That's because conventional farming often leads to higher carbon emissions than organic growing.

"Although there are a number of benefits to growing organically, avoiding the use of synthetic fertilizer is a big deal in terms of carbon emissions," says Sonja Brodt, Ph.D., associate director at the University of California-Davis's Sustainable Agriculture Research and Education Program. "Even if [organic growers are] bringing in manure, it's better than synthetic fertilizer," she says. Not only does synthetic nitrogen-based fertilizer require a tremendous amount of energy to produce, nitrous oxide, a gas that is produced by microbes in the soil (and emitted at a higher rate when synthetic fertilizer is used instead of natural fertilizer), is 300 times more potent than carbon dioxide as a greenhouse gas.

"In general, we would like to see foods produced more in concert with the environment and utilizing natural cycles," says Gail Feenstra, Ph.D., SAREP's director. It may even be that foods produced further from home that use organic systems are less carbon-intensive than local conventional products.

3. It's good to try to buy fresh, seasonal food that grows naturally in your area.

It can feel good to buy things like citrus from a local grower. However, if fruit must be produced in heated greenhouses or with lots of water and fertilizer, the carbon emissions created by those inputs may outweigh the benefits of reduced transportation. That's why it's best to buy local foods that are well-suited to natural growing conditions in your region. They will take fewer inputs to grow naturally since the soil, climate and other conditions match with their preferences.

In addition, eating seasonally is also a good idea. Even foods that grow well in certain regions of the country will require more support if they're forced to grow at a time they wouldn't otherwise. (Tomatoes, for example, may need to be produced in greenhouses or under hoop houses.) Shopping seasonally ensures you get the freshest fruits and veggies possible. It also discourages people from splurging on out-of-season foods produced in other countries.

4. Decreasing meat consumption is better than buying local meat.

Meat and animal products will always have a bigger environmental impact than plant foods, regardless of where or how they're produced, so cutting back on those foods in general is the most sustainable option. For every kilogram of beef produced, an estimated 99 kilograms of carbon dioxide equivalents are emitted. That's compared to poultry, which emits 10 kg CO2eq per kilogram produced and tofu, which emits 3 kg CO2eq. Nuts emit just 0.43 kg CO2eq per kilogram produced.

Of course, there are other environmental costs to produce these low-emitting foods. Almonds, for example, require a hefty amount of water to grow. However, red meat still has twice the environmental impact as nuts, according to one study in PNAS in 2019, which looked at the environmental consequences of producing 15 foods. The researchers found that the healthiest foods (whole grains, fruits, vegetables, legumes, nuts, olive oil and fish) also had lower environmental impacts compared to less-healthy fare, including unprocessed and processed red meat. Moving toward these foods can both be good for you and the environment.

Bottom Line

The next time you visit a farmers' market or supermarket, think less about food miles and more about what you're eating, whether it makes sense for your region and time of year, and how it was grown, to make your purchases an even brighter shade of green.