Is a vegan diet less sustainable than an omnivorous diet?

References to one particular study on diet and land use requirements keep popping up around the web, from various blogs and news organizations.

rude-151093_640Most of them have been quick to jump on this study because it seems to offer them an opportunity to thumb their noses and blow raspberries at the vegan community, for example, “Sorry vegans: Sticking to a meat-free, dairy-free diet is NOT as good for the planet as you might think”. Many of them start with some kind of elbow to the rib, something about how we like to think we’re better than everybody else or some such nonsense. Some are more respectful.

What all of them have in common is a serious lack of understanding of the specific point made by the authors, and even the authors themselves seem to miss the forest for the trees. I’ll explain.

First, here’s a link to the specious article under discussion: Peters et al. 2016. It’s licensed under the CC attribution license and available for everyone to read for free (yay!).

salad-1570673_640The key measure under investigation was the carrying capacity of U.S. agricultural land – basically, the annual per capita land requirements vs. amount of land available for food production when that food is in keeping with different diets. More simply, how many people can be fed with the amount of land that we have? The authors look at various levels of omnivorous diets, lacto-ovo and lacto-vegetarian, and vegan, as well as 2 variants of current consumption.

They begin with 2 fundamental assumptions: there is a relationship between diet and sustainability, specifically, “dietary change is essential for meeting future human food needs”. Agreed. Second: “sparing land from conversion to agriculture may be important for protecting biodiversity”, so it’s vitally important to understand how dietary patterns impact land use. So far, so good.

cows-1029077_640The authors caution against simplistic thinking because, though animal agriculture is the most land-intensive, the largest fraction of land it uses is for foraging and grazing, often on non-arable land – land that can’t be used to grow any crops for human consumption, though grasses and other ‘weeds’ will grow which the animals eat. So, as they point out, eliminating animal agriculture does not necessarily mean turning all its land over to cultivation.

So, I can definitely see where they’re coming from. It’s a logical argument. If we want to make the most of our land for food production purposes, then we need to use it for what it’s good for. Attempting to make non-arable land supportive of crops causes environmental devastation (just look at the Aral Sea crisis). And it’s clear from the numbers in Peters et al. (2016) that the most efficient use of land for food would include using non-arable land for animal agriculture.

There are 2 implicit assumptions the authors are making which are simply untrue. First, that there is such a thing as an omnivorous diet that is healthy. Nope. Not only is the ingestion of animal products devastating to human health, but the killing and handling of dead animals causes psychological disorders in the people who do that kind of work, and passes unknown numbers of diseases on to anyone who handles raw meat, producers & consumers alike.

Second, that the most efficient diet in terms of land use is the most sustainable diet. Efficiency does not equal sustainability, and animal agriculture is far too devastating to the environment to be considered as part of the future of a sustainable food supply. The following information and more is available on the Cowspiracy website’s fact sheet.

  • ocean dead zones, water pollution, & habitat destruction are largely driven by animal agricultureclean-1223168_640
  • livestock and their byproducts account for 51% of global greenhouse gas emissions
  • animal agriculture is the leading driver of desertification
  • the U.S. could feed 800 million people with just the grain that is currently fed to livestock (that’s more than double the current U.S. population and slightly more than the total number of starving people in the world, according to United Nations World Food Program statistics)
  • more than 80% of the world’s starving children live in countries who export their grain to feed livestock, which are then consumed by people in wealthier countries – an absolute crime against humanity

What I’m trying to say is that it doesn’t actually matter what the most efficient use of land is, because any animal agriculture at all does more harm than good and, if we turn over all the currently arable land to cultivation for human consumption, we could easily feed the global population with room to grow, and if we eventually do outgrow it, we can still work with what we’ve got and use our technology to find better solutions like vertical farming.

Something I often hear vegans say, and see in vegan blog posts is that we don’t need to consume animals and their products to be healthy and happy, but we can make a much stronger statement than that – because it’s true – consuming animals and their products at the rate we currently do is not only antithetical to human health & happiness, but even to our survival as a species.



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