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Notes
Technically, rainwater that is incorporated into a product (e.g., literally containing in meat) is also included in the green water footprint of a product. The volume of rainwater (about 1500 gallons per pound of meat) lost through evaporation and transpiration from pasture forage swamps (no pun intended) the water that is literally contained in one pound of meat. Thus, in what follows we can safely set aside the rainwater incorporated into meat itself.
A third component sometimes factored into a water footprint is grey water. Grey water is water that would be needed to reduce pollutants released in agricultural operations to acceptable levels. Such pollutants include fertilizer, pesticide, and manure runoff. Grey water is not considered here. It is not consistently used in the scientific literature on water footprints of food, so it is not even mentioned in the meta-analysis by Harris et al. (2020), upon which I rely later. There appears to be good reason for this, as grey water is not an actual volume of water that is used in food production. It is a merely theoretical volume that would be used if pollutants were reduced to acceptable levels. It is thus a proxy for, or indicator of pollution, rather than a measure of actual water use. On these reasons to exclude grey water, see Hadjikakou, Chenoweth, and Miller (2013, p. 551).
While there is indeed some debate about the use of farmland for solar (photovoltaic) electricity generation rather than for agricultural production, recent research suggests that solar electricity generation and agricultural production can coexist on the very same piece of land to the benefit of both. In this connection, see Adeh et al. (2018), Barron-Gafford et al. (2019), and Adeh et al. (2019). This reinforces the point that solar energy is so abundant that there is no debate about whether to use it for producing crops, livestock, or electricity. The debate is about land use. Since the land can be used for both agriculture and solar electricity production, there is no need for debate.
See section 3.4.2 for the details on how much water is saved by these and other conservation measures.
Again, see footnote 2. A comparatively miniscule amount of green water is contained in meat.
Why should the reference point be the pasture as it stands? Evapotranspiration is highly dependent on what is grown on the land, so perhaps the reference point should not be the pasture as it stands, but some other crop, or allowing the pasture to revert to forest. While this line of thought is important to consider, the evapotranspiration associated with grazing pasture is considerably less than for a host of crops grown for plant-based food, including broccoli, brussels sprouts, cabbage, carrots, cauliflower, celery, lettuce, spinach, tomatoes, eggplant, cucumber, melons, beets, peanuts, peas, wheat, corn, rice, potatoes, almonds, apples, cherries, pears, apricots, and peaches (Allen et al. 1998, Chapter 6, Table 12). It is also less than a forest of conifer trees (Allen et al. 1998, Chapter 6, Table 12). In fact, deforestation has decreased global vapor flows by 4% (Gordon et al. 2005, p. 7612), so letting the land revert to forest would result in more green water use. Thus, using the pasture as it stands as the benchmark rather than some other agricultural use or reversion to forest seems reasonable and even generous to my interlocutor.
In an apparent attempt to make premise 3 appear true, People for the Ethical Treatment of Animals conflates green water and blue water when they claim: “You can save more water by not eating a pound of meat than you can by not showering for six months!” (People for the Ethical Treatment of Animals, 2022).
For example, Rachels (2011, p. 890), Kemmerer (2015, p. 32), and McPherson (2018, p. 214) cite the land footprint of a diet with ASF as a reason against such a diet. The idea behind land footprint arguments is presumably similar to the idea behind water footprint arguments: Land is a limited resource and we have reasons to use limited resources in more rather than less beneficial ways.
“Average” diets are “those identified as current, baseline, or average intake” in a given study (Harris et al. 2020, p. 377). “Healthy” diets are those that provide additional nutritional benefits in comparison to average diets and typically satisfy national dietary guidelines or World Health Organization guidelines (Harris et al. 2020, p. 377). No mention is made whether the diets identified as vegan in the meta-analysis were healthy or unhealthy.
Also relying on the scientific literature, philosopher Mark Budolfson points out that some vegan protein staples (such as almonds, lentils, and beans) have overall water footprints that rival or exceed the water footprints of some meats per unit of nutrition (2016, Table 9.1).
For other continents, the daily blue water footprints of average diets are as follows: Africa, 163 L; Asia, 382 L, Europe, 241 L; Oceania, 230 L; South America, 202 L (Harris et al. 2020, Table 1). The (unweighted) global average is 240 L per day, so the figures I go on to present in the text for North America are close to the global average.
Higher education levels are positively correlated with healthier diets. See, for example, Rippin et al. (2020).
See Bruckner (2020) for a fuller argument for the view that the harm minimization reasoning often used to support a moral requirement of veganism overgeneralizes in this manner.
Budolfson (2016) introduces the idea of a harm budget for a diet as part of his rejection of arguments for veganism that rely on the greater harm associated with some ASF. His idea is that a careful omnivorous diet has a lower harm footprint than a typical vegan diet, so that if a typical vegan diet is under one’s harm budget, then so is a careful omnivorous diet. One can also make use of the idea of a harm budget not just for a diet but for an overall lifestyle as part of an argument that a diet including ASF can be part of a lifestyle that is under one’s harm budget (Bruckner, 2020). In the present contribution, I am applying this budgetary idea to the blue water budget of a lifestyle.
One reason for refraining from this speculation is that an individual’s blue water budget will be highly dependent on the abundance or scarcity of blue water where she lives as well as the abundance or scarcity of blue water where her food is produced. For example, if blue water is locally abundant, cannot be diverted or transported to places where it is less abundant, and its local use will not create downstream scarcity, then the threshold of permissible local withdrawals will be much higher than if blue water is already locally scarce due to climatic conditions or anthropogenic depletion. Another reason to refrain from trying to investigate the threshold here is that it is simply another project that would surely take at least another paper to attempt. Here I am merely motioning in the direction of a way forward in thinking about morally permissible blue water use after I have accomplished my main task of looking at the strength of the moral reasons provided by the green and blue water footprints of ASF.
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Bruckner, D.W. Water Footprints and Veganism. J Value Inquiry (2024). https://doi.org/10.1007/s10790-023-09974-1
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DOI: https://doi.org/10.1007/s10790-023-09974-1