How Diet Impacts Climate Change

Choices matter when it comes to what we eat and how we get our food

By Amanda McCracken Did you know the average American’s diet has a larger negative impact on greenhouse gas emissions (GHGE) than the average British or German diet? Many people know industrial agriculture contributes to GHGE, but what’s the carbon footprint of individual diets? A study published in “The American Journal of Clinical Nutrition” looked at food choices made by 16,000 Americans in a single day. Not surprisingly, the choices with fewer impacts on GHGE were also healthier, while diets high in meat and dairy products were more significant contributors to GHGE. People who had the highest-impact diets contributed five times more to overall emissions, compared with Americans with the lowest-impact daily diets. The study also showed that men tend to eat higher-impact diets than women.

But what about eco-conscious Boulder, which is consistently ranked one of America’s healthiest towns? University of Colorado instructor Nicole Civita says the town could do a lot better, food-wise. Civita is the sustainable food systems specialization lead for the Masters of the Environment Graduate Program at the University of Colorado. As such, she researches and teaches food ethics and the values and trade-offs related to food choices. “We often get a green halo around Boulder’s role in the local, national and global food scene, since it’s such an epicenter of natural and organic foods,” Civita says, “but folks tend to have a narrow understanding of the varying ways in which food choices impact climate change.” She points out that just because a food is marketed as “natural” doesn’t mean it’s environmentally responsible. “It’s not just about choosing the right brand. We need to think about our dietary pattern as a whole,” she says. Different values are embedded in different diet choices, she notes. “None of us are going to have a perfectly ethical diet, so focus on where you want to have your impact.” For instance, dietary choices can impact water quality, climate change, animal welfare, biodiversity and public health. Choose a value to improve through your choices, she suggests.

According to this diagram by the Eat-Lancet Commission, a planetary health plate should consist by volume of approximately half a plate of fruits and vegetables. The other half should primarily consist of whole grains, plant protein sources, unsaturated plant oils and (optionally) modest amounts of animal protein sources.

Shifting to a more plant-based diet or making sure the meat and milk products you consume in moderation are responsibly produced in regenerative ways does make a difference. “The American Journal of Clinical Nutrition” found that low-GHGE diets had less meat, dairy and solid fats (saturated fats), and more poultry, plant-protein foods (legumes, soybeans, nuts and seeds), oils and whole and refined grains. The EAT-Lancet Commission published concurring results in “The Lancet.” The report noted “foods sourced from animals, especially red meat, have relatively high environmental footprints per serving compared to other foods.” This impacts GHGE, land use and biodiversity loss. “This is particularly the case for animal-source foods from grain-fed livestock,” the report states. One way to mitigate these impacts is to source, buy and eat more sustainably produced food, including when you eat out. Civita suggests eating at restaurants that source food from local farms. “Local sourcing is a way to find farms that use regenerative agricultural practices, like building soil and sequestering carbon,” she says. Locally produced products have shorter supply chains and a greater opportunity for transparency, so “this can be a good way to source meat, dairy and eggs, in moderation, that are produced in ways that help address climate change.” Leaf Vegetarian Restaurant serves organic produce grown at its Three Leaf Farm in Lafayette and Black Cat Farm Table Bistro prepares produce and animal products grown at its Black Cat Organic Farm. Other locally owned companies are members of the Colorado Grain Chain, which supports grain and grain products made with heritage, ancient and locally adapted grains. Louisville’s Moxie Bread Co. is a member of Colorado Grain Chain, as are other local restaurants, breweries and farmers. Waste Not, Want Not Farming practices also contribute to GHGE, particularly single-crop agriculture. “Monoculture is a very resistant, rigid and vulnerable system,” Civita says. “When we diversify what we eat, for example, including a range of grains in our diet, we help create markets for various crops that farmers can rotate to build healthier soils and reduce weed and pest pressures. Diversifying crops also builds resilience—a hedge against the impacts of climate change.”

Mad Agriculture works with farmers in the high plains and Midwest to create regenerative farm plans. In 2019, the group worked with Boulder’s Black Cat Organic Farm (pictured above). “We created a farm vision and then walked the land to determine how to make proactive changes,” says Mad Agriculture’s Jane Cavagnero.

As climate change alters Colorado’s precipitation patterns, it becomes more imperative to support farms that grow less water-intensive crops, like millet, sorghum and quinoa, as opposed to wheat and corn. And though hemp is a new and burgeoning Colorado market, it’s also a nitrogen- and water-intensive crop, Civita says. Shopping where your dollars support social welfare also helps the environment. “If people can’t afford to purchase the kind of foods with low environmental impact, then we are all contributing to climate change and perpetuating social and economic injustice,” Civita says. Food waste is a formidable factor in GHGE. Decomposing food emits methane—far worse than carbon dioxide in terms of its heat-absorbing potential, which adds to emissions and wastes the resources that were needed to produce, transport and store the food. “Don’t buy what you hope you’ll eat, but what you know you’ll eat,” Civita says. She recommends making a weekly food budget and anticipating how to repurpose leftovers. “With less food waste, less food needs to be produced to feed the world,” notes the EAT-Lancet Commission. Keep food you need to eat first on an eye-level shelf, and use your freezer. When Civita’s yogurt is close to the expiration date, she puts it in freezer trays with fruit and enjoys yogurt pops later. “With very few exceptions—hot dogs, deli meats and seafood—it’s fine to use your senses and not the date on the package, which is typically just an indicator of when the product is expected to have less than optimal taste or texture,” she says. By swapping a few things in your diet and making thoughtful choices, you can help mitigate global warming and safeguard our planet’s future.

Insects, Anyone?

Looking for a protein-rich food with a small carbon footprint? Try chapulines! Savory Spice owner Dan Hayward recently returned from a culinary vacation in Oaxaca, Mexico—a gastronomic paradise known for offering some of the insect world’s best delights. Most notable, he says, were the chapulines, or grasshoppers and crickets. “Oaxaca has no shortage of these high-energy, protein-packed sources of interesting flavors and textures that you can find in the finest dining establishments and from street vendors alike.” Hayward says his Caribbean, Latin American or Tex-Mex/Southwestern spices will enhance any hop-along meal. Chapulines are available at Mexican markets and online from specialty suppliers.

How Diet Impacts Climate Change

Choices matter when it comes to what we eat and how we get our food

Insects, Anyone?

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