By Jeanne Yacoubou, MS

If you’re a vegan for the environment, should water footprints or carbon footprints of food matter more to you?

You’re probably aware that almost all large studies and meta-analyses compiling results of several studies conclude that vegan diets have the smallest water footprint and carbon footprint of all diets. The reason is that it takes much more water and fossil fuels to produce meat and dairy compared to plant foods. Additionally, the methane and nitrous oxide generated from animal agriculture supercharge climate breakdown.

However, there are a few vegan foods – such as almonds, olive oil, and coffee – that have astronomical water footprints. And rice’s carbon footprint is much higher than those of other grains (and almost as high as that of chicken eggs) because of the methane produced from growing rice. Although in these cases, the water usage and carbon emissions are small compared to those produced by meat and dairy production, they are still significantly more than those of other plant foods.

So, what’s a vegan to do?

Water vs. Carbon Footprints of Foods

If you’re trying to live more sustainably as a vegetarian or vegan, it’s important to consider both the water and the carbon footprints of food. In cases where a particular vegan food has an extremely high water footprint or carbon footprint, you may choose other options whose footprint is not as high. Fortunately, as a vegan, you have plenty of other options.

However, even if you decide to stop eating certain vegan foods because of their heavy water or carbon footprints, you don’t need to count up those footprints of every food on your plate at every meal. Almost all studies show that vegans’ personal food footprints are already the lowest of all. Vegetarians have smaller food footprints than meat eaters do, although not as low as vegans have in most cases.

Whatever you choose to do in the name of living lightly on the Earth, remember that there’s more to sustainable food than just water and carbon footprints as we discuss below.

Water, Carbon, and Environmental Footprints of Food

It would be helpful to everyone striving to adopt a sustainable diet if there were tables of information listing the environmental footprints of foods. This metric, in theory, would contain not only water usage and carbon emissions associated with foods. It would also include, for example, the effects of a food’s production in relation to:

• land use (including deforestation)
• eutrophication potential
• acidification potential
• fossil resource use
• aquifer depletion
• air pollution
• biodiversity

As you may imagine, calculating the environmental footprints of foods is much more complicated than figuring out water or carbon footprints. As of this writing, the best source for the environmental footprints of foods is Michael Clark et al. It’s by no means complete, but it’s a good start.

Based on our reading of the scientific literature, foods with either a high water or carbon footprint have a heavier environmental footprint compared to foods that have neither. However, no comprehensive study that we’re aware of  has been done to substantiate this point, although the Clark et al. work supports it as we describe in our recent article.

Although research into the water and carbon footprints of foods is more advanced, there are many variables that influence final results. Soil condition and type, farming method, and climate are some of the major reasons why water and carbon footprints will vary from source to source and over time. So, think of any numerical value you see as an approximation, highly dependent on a host of factors that will be different from place to place and season to season.

Due in part to these differences, there are a few case studies which calculate certain plant foods as having greater blue (surface or groundwater) water footprints than some animal foods or carbon emissions comparable to those of meat or dairy. Generally, meta-analyses considering dozens or more of these studies show plant-based diets have smaller water and carbon footprints than animal-based diets. Conclusions from meta-analyses are more credible than small case studies done in a particular area.

To date, the best resource for finding out the water footprints of food is Mekonnen & Hoekstra. Note, however, that this work was published in 2011 and based on even earlier data. Because of climate breakdown, (extended drought and erratic rainfall patterns in many countries that have become common in the last few years), these data do not reflect the growing reliance on blue water for irrigation. So, for example, the blue water footprints of certain crops, such as avocado, have become significantly higher than what Mekonnen & Hoekstra reported.

For the carbon footprints of food, Poore & Nemecek is the most reliable source so far. Our World in Data has compiled a graphical interpretation of their work that is useful.

The Vegetarian Resource Group has already provided detailed information on the water and carbon footprints of many foods from these sources in several of our earlier publications, such as our water pollution brochure, vegan burrito infographic, and carbon footprints of vegan pizza article.

Do Personal Carbon Footprints Matter?

A 2023 study analyzing personal income and investment data from 1990 to 2019 in the United States showed that:

• 40% of total U.S. carbon emissions were associated with the top 10% of households.
• The top 1% in the U.S. were responsible for 15-17% of national carbon emissions.
• Of the top 1%, their investments accounted for 38-43% of their carbon emissions.

Although this study did not describe the carbon intensive lifestyles of the most affluent Americans, frequent air travel and car use are the major sources of carbon emissions for this group followed by home energy use. (Although the #1 way to reduce your personal carbon footprint is to have no or fewer children.) Comparatively speaking, diet is not a major source of the wealthy’s personal carbon footprint.

Remember that the notion of a personal carbon footprint was created by the fossil fuel industry as a marketing tactic to shift the focus away from their products as causing climate breakdown and placing responsibility on to individual people. However, although you didn’t cause the problem as an individual through your food choices, this doesn’t mean you should disregard the effect of your food on the environment and eat whatever you want. It’s always best to limit your consumption of unsustainable foods if possible – for health, environmental, and ethical reasons.

Personal vs. Global Carbon and Water Footprints

One person’s dietary choice is not going to solve the crisis of rapidly dwindling freshwater reserves all over the world or the planetary climate crisis. However, one person’s food preferences can have the following effects, which, when multiplied by millions of people, could lead to system change. In turn, a habitable planet with abundant resources for future generations could result.

As Nielsen, et al. describe in their 2021 article, you can influence those around you and society as a(n):

• Consumer, through your purchases of vegan or vegetarian products
• Investor, choosing a bank, lending agency, or stocks that aren’t associated with animal agriculture or fossil fuels
• Role model for friends, family, and co-workers, through your dietary choice
• Employee or student, requesting vegan options in the cafeteria or at company parties, reducing food waste by donating it to local shelters, and divesting from fossil fuels
• Citizen, contacting your government representatives to act on climate via increased funding for vegan or vegetarian initiatives in public schools and elimination of subsidies for animal agriculture; voting for candidates who support these positions or running for office yourself

So, as an individual, you have at least these five ways to make your diet’s environmental footprint matter. When you do, the ripple effects of your choice will be felt by many others.

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