Every food-related action you take calls a world into being. We call this world the food system, and it is a vast network of farms, fisheries, processors, manufacturers, stores, restaurants, and home kitchens. These production systems are knit together by a distribution system of roads, rails, waterways, airways, and storage facilities that crisscross the globe. When you buy food, grow food, prepare food, serve food, or eat food, you make choices. And, these choices can either use resources directly, or tell others to use resources to make food available.

Each part of this system affects the environment in some way. Vehicles and machinery need energy to run. Packaging creates waste to be disposed of. Farms require land, and sometimes irrigation water, to grow crops. Thus, every action we take either has a direct impact, such as burning gas on a stove, or an indirect impact, such as the land used to grow wheat for bread. Indeed, every food purchase tells the food system, “Please keep supplying this item, and by the way, whatever you’re doing to produce this food is fine by me.”

So how do our food choices influence the environment? With so many issues on the proverbial table (e.g. climate change, land use, water use, soil erosion, deforestation, aquatic “dead zones,” biodiversity loss, and so on), the question can seem overwhelming. However, most of our impacts can be placed into two categories, (1) use of natural resources and (2) polluting or degrading ecosystems. Consider a couple of examples.

We’ll start with natural resources, using land as an example. Most food in the diets of people around the world comes from land-based systems. Land, and the soils that cover it, hold the potential for supporting plant life, provided there is sunlight, suitable temperatures, and ample water available. Agriculture turns these resources into crops and livestock, much of which becomes part of the human food supply. In the process, agriculture takes the place of whatever natural ecosystem would have grown in that location. This could be a prairie, a forest, or even a desert.

On the one hand, this is just an ecological process, with domesticated species replacing wild ones. On the other hand, the conversion of enough land can undermine the ecosystem of the surrounding area.

How much is too much? That is a question for another day. Suffice it to say that scientists generally agree humanity should contain agriculture within its current footprint. As a result, we should care about the land use implications of our food choices.

Let’s now look at pollution, using a large, unwieldy but essential to understand example: climate change. The food system, like most other human systems, relies on fossil fuels for much of its energy. People invented food-making and processing machines to reduce the number of person-hours it takes to produce a pound of food.

At risk of oversimplifying, substituting machine energy for human energy tends to make food cheaper or more plentiful – or both. Alas, using machines also releases more carbon dioxide in the process of production than human labor. Let’s think of pasta. If a machine makes it, that takes more fossil fuel energy (more carbon dioxide production) than if a human makes it by hand. However, more pasta is made and distributed to more humans more quickly with machinery.

Likewise, humans rely on fertilizers to support higher crop yields. This has increased the amount of nitrogen in global circulation and the emission of nitrous oxide, a potent greenhouse gas. Finally, methane is also produced in food production. It’s not just livestock manure management and ruminant digestion that cause methane. Rice production, due to the need to flood fields, emits methane. And methane is another potent greenhouse gas – more potent than carbon dioxide.

All this to say: We need to look at all the gases emitted in the food production system, not just one, and try to balance and reduce their effects. The scientific consensus on climate change is quite clear: emissions must be reduced. How do we reduce emissions from the food system? Again, this is a question for another day, but the answer will undoubtedly involve changes to what we eat and how we produce it.

So, where does this leave us regarding our original question? Rather than focusing on specific impact types, I will leave you with a few general points:

1. Every action counts. No food, even home-grown or self-caught food, is impact-free. All food has a footprint – so try not to waste food.
2. Many of the environmental impacts are inherently negative toward the environment. Appropriation of land, for example, reduces habitat for other species. However, some of these environmental impacts could be made neutral, or at least less negative, with better management. For example, reducing erosion and returning more plant biomass to soils can actually capture carbon.
3. Food systems also produce positive impacts. Enjoying what you eat, good health, and good livelihoods can all be benefits of a more sustainable food system. These are the things we want from food systems.

Given these three points, recognize that food systems are complicated. In trying to understand the impact of your actions on the environment, be sure to think carefully, to listen to other arguments, and to reconsider your opinions when shown new evidence. Know that trade-offs abound between human benefits and ecosystem benefits and be ready to examine not only facts but also your own beliefs.

Answered by Christian Peters, Tufts University

About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified, professionals in the areas of growing our world’s food supply while protecting our environment. We work at universities, government research facilities, and private businesses across the United States and the world.