Buying Local: Do Food Miles Matter?
Assistant Professor of Environmental Health and Exposure Disparities, Harvard T. H. Chan School of Public Health
Gary Adamkiewicz, instructor of From Farm to Fork: Food, Sustainability, and the Global Environment, discusses the nuances of food miles and their impact on our climate.
I am dependent on foreign oil.
Not that kind. Olive.
Whether it’s grapes from Chile or olive oil from Italy, odds are, you consumed something today that logged more than 1,000 miles from the farm to your fork. Concerns about the effects of this transport on our climate have inspired many to embrace their inner “locavore” by limiting the food miles on their dinner plate.
Will buying local food slow climate change?
The short answer is that buying local food is a good principle, but not a universal rule. Some of the biggest climate effects can happen before a corn cob leaves the farm or a steer leaves the feedlot.
To quantify this, we need to account for all steps in the lifecycle of our food, from cradle to grave. Transportation is just one slice of that lifecycle. The figure below, based on an analysis by the Environmental Working Group (EWG), illustrates this fact by separating the effect of production from emissions once the food leaves the farm.
Lamb, beef, and pork are among the biggest climate offenders. And these effects are not driven by their transport. In fact, a 2013 United Nations report showed that globally, livestock represent 14% of all greenhouse gas emissions. This would be comparable to emissions from cars, trucks, buses and other transport combined.
For the climate, your dinner might increase your carbon footprint more than your driving.
What’s driving production emissions?
For produce, production emissions can include the energy that goes into chemical fertilizers and pesticides, the diesel-powered farm equipment, or greenhouses heated to extend the growing season.
For livestock, it’s all that and more because we grow large quantities of feed grain. It can take more than 10 pounds of grain to produce one pound of beef. If that grain is energy-intensive, that beef is going to be much more so. And by the way, cows and other ruminant animals also belch methane, which has 21 times the greenhouse potential of carbon dioxide.
As you move toward the right in the EWG figure above, the impacts decrease. But food miles represent a more significant portion of a food’s climate impact. In relative terms, it might be worth trimming some miles off of your broccoli’s trip. For many of us, though, changing what we eat can have a bigger effect than changing where it’s from.
There is a lot to consider, and it can be confusing. The subtleties are evident in cases where our intuition fails. For example:
- A study published in 2009 showed that for consumers in the eastern United States, a French wine can have a smaller carbon footprint than wine from Napa Valley since the ocean transport has a smaller footprint than a cross-country trip by diesel truck.
- A 2006 report showed that, for consumers in the United Kingdom, lamb imported from New Zealand had a smaller carbon footprint than UK-raised lamb, including the effect of shipment from New Zealand. How can this be? New Zealand sheep are generally pastured and raised on farms using hydroelectric power. This represents such a big energy savings over UK sheep fattened by commercial grain that you can still afford the fuel cost of the 11,000-mile cruise from New Zealand.
5 steps to reduce your carbon footprint and improve your MPG
In general, choose options that provide more meals per gallon (MPG) by using these five guiding principles.
1. Lower your food chain standards.
Your overall dietary pattern can be more important than how far your food travels. Foods derived from livestock accumulate impacts along the entire food chain that feeds them, so eating lower on this chain is a better path. Moving toward a plant-based diet is a classic case of win-win-win: better for the environment, better for the climate, and better for your health. You don’t need to be an uber-vegan to make a difference. Start by swapping a few meals each week.
2. Bad if by land, good if by sea (and worst if by air).
Limit your consumption of foods that are shipped by air, such as asparagus and many berries from South America, which need to get to market quickly. Remember that long trucking hauls can pack a climate punch. Rail transport is efficient, but much less product moves this way in the United States. Sometimes a long container ship voyage can be worth it if the food has a small production footprint (like the New Zealand lamb). See the National Resource Defense Council’s Health Facts for more information on food miles and which foods travel by air.
3. Local is more than nearby.
Expand your view of local beyond space and into time. Purchasing in-season produce should be another goal, since you will likely avoid energy sinks like heated greenhouses and cold storage. Check out the National Resource Defense Council’s Eat Local Map for information on farmer’s markets and seasonal eating near you.
4. Go to the source.
Processing, packaging, heating, and refrigeration all consume energy. So avoid highly processed foods. When you incorporate fresh, local fruits and vegetables into your meals, you save some energy-intensive steps and perhaps some petrochemical-derived packaging along the way.
5. Be COOL.
It never hurts to know where your food comes from. Starting with the 2002 Farm Bill, the United States began requiring country-of-origin labeling (COOL) for certain foods. The list now includes beef, veal, pork, lamb, goat, chicken, fish, shellfish, and fresh and frozen fruits and vegetables. This labeling can help you understand the miles embedded in your dinner.
Don’t get me wrong, there are many reasons to support local food. Just know that a “local above all” strategy is not foolproof. Ask questions, weigh options, and you can be a climate-friendly consumer.
It is still good advice to support your local farmer and farm stand and establish relationships with producers who try to be sustainable. But remember, climate change is one consideration. Our food decisions can be influenced by other factors, such as ethics and personal health.
In full disclosure, I am sticking with my olive oil.
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