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Study: You Emit Two Tons of CO2 Each Year From Eating

Your bad eating habits don't just harm you; they also hurt the planet. That's what a study from the Universidad de Almería (UAL) claims. According to researchers, individual food consumption is responsible for emitting approximately two tons of carbon dioxide each year from the time food is produced to when it is excreted. That's over 20% of the average person's yearly CO2 emissions in Spain, where the study was conducted.

The news shouldn't be all that surprising—animal production (including emissions from cow burps and farts), transportation, food packaging, and preparation are all familiar causes of greenhouse gas emissions. But human excrement? The study takes into account the CO2 produced by the human metabolism, as well as the emissions generated by toilet paper and toilet water.

Human excrement is responsible for more than just emissions. Iván Muñoz, the head author of the study, explained to ScienceDaily, "Human excretion contributes significantly to water polluting through providing organic matter and nutrients, such as nitrogen and phosphorus, which fosters the growth of algae, a decrease in the level of oxygen dissolved in the water, bad smells and other problems associated to eutrophication."

Returning wastewater back to the environment isn't a bad thing in theory, but many rivers have low water levels, making it difficult to soak up excrement, pesticides, fertilizers, and other pollutants.

There isn't much we can do about reducing the amount of excrement produced by our bodies, but we can cut down on carbon emissions—the UAL study shows that diets low in meat and dairy products have a lower overall environmental impact. We're still waiting to hear back from PETA, but we imagine that the carbon emissions argument is a powerful way to get consumers to change their dietary choices.

Ariel Schwartz can be reached on Twitter or by email.

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  • Dawn Lesley

    This article unfortunately is misleading, but it does provide an opportunity to clarify the topic of carbon emissions.

    Carbon emitted by the metabolism of living organisms is part of the natural carbon cycling in the biosphere, it ALL originates from solar energy harvested by plants, even when we eat meat. The planet hummed along this way for millennia, fully solar powered, cycling carbon and indefinitely sustaining life in ever-increasingly-complex food webs. As many have pointed out, there were certainly cyclic patterns of global weather changes, which created evolutionary pressures and migrations etc. However except for the occasional volcanic hiccup or meteor strike, most of these shifts were relatively gradual.

    The industrial revolution changed all that, and we're seeing the results of a hundred-plus years of humans digging up carbon sequestered in the Earth's crust, burning it, and spewing it into the biosphere, where it is accumulating to devastating effect.

    It is true that when we truck (or fly) food around in fossil-fuel-burning vehicles, and cut down trees (a not exactly long-term but say middle-term carbon sequestration bank not usually associated with the fast cycling associated with eating food) and burn fossil fuels to turn the trees into toilet paper, then truck the toilet paper around, we do have 'extra' emissions associated with that.

    And when our population grows to the extent that we need to mine carbon from the ground to fertilize enough crops to feed this outsized population (that is, because solar energy inputs alone do not grow food fast enough to feed all of us), and we pump and truck excrement around to protect the vast human population centers, we also have 'extra' emissions associated with that.

    But this article implies that the mere fact of being alive and eating is causing climate change. Nope. Not even if you eat 100% steak. As long as all of it is grown close enough to your kitchen for you to eat it without burning fossil fuels, you're just Part of the Glorious Mystery of Mother Earth, breathing the oxygen generated by the trees breathing the CO2 generated by you, eating the food grown by the sun, pooping the fertilizer to grow the food. Just keep trucks out of the equation, and we can re-align ourselves with the Natural Order. Having fewer babies wouldn't hurt either!

    It's important to distinguish between fossil-fuel-generated carbon and solar-energy-cycled carbon. We all need to understand this science well, if we're to make better short- and long-term choices.