The question, then, that I'm ultimately asked is what I mean by "environmental sustainability." Well, Kathy Freston over at The Huffington Post puts it very articulately in this blog entry.
A few highlights:
"Last month, the United Nations published a report on livestock and the environment with a stunning conclusion: "The livestock sector emerges as one of the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global." It turns out that raising animals for food is a primary cause of land degradation, air pollution, water shortage, water pollution, loss of biodiversity, and not least of all, global warming.
They noted that feeding animals for meat, dairy, and egg production requires growing some ten times as much crops as we'd need if we just ate pasta primavera, faux chicken nuggets, and other plant foods. On top of that, we have to transport the animals to slaughterhouses, slaughter them, refrigerate their carcasses, and distribute their flesh all across the country. Producing a calorie of meat protein means burning more than ten times as much fossil fuels--and spewing more than ten times as much heat-trapping carbon dioxide--as does a calorie of plant protein. The researchers found that, when it's all added up, the average American does more to reduce global warming emissions by going vegetarian than by switching to a Prius.
According to the UN report, it gets even worse when we include the vast quantities of land needed to give us our steak and pork chops. Animal agriculture takes up an incredible 70% of all agricultural land, and 30% of the total land surface of the planet
[...] the real kicker comes when looking at gases besides carbon dioxide--gases like methane and nitrous oxide, enormously effective greenhouse gases with 23 and 296 times the warming power of carbon dioxide, respectively. If carbon dioxide is responsible for about one-half of human-related greenhouse gas warming since the industrial revolution, methane and nitrous oxide are responsible for another one-third. These super-strong gases come primarily from farmed animals' digestive processes, and from their manure. In fact, while animal agriculture accounts for 9% of our carbon dioxide emissions, it emits 37% of our methane, and a whopping 65% of our nitrous oxide.
It's a little hard to take in when thinking of a small chick hatching from her fragile egg. How can an animal, so seemingly insignificant against the vastness of the earth, give off so much greenhouse gas as to change the global climate? The answer is in their sheer numbers. The United States alone slaughters more than 10 billion land animals every year, all to sustain a meat-ravenous culture that can barely conceive of a time not long ago when "a chicken in every pot" was considered a luxury. Land animals raised for food make up a staggering 20% of the entire land animal biomass of the earth. We are eating our planet to death.
What we're seeing is just the beginning, too. Meat consumption has increased five-fold in the past fifty years, and is expected to double again in the next fifty.
[...] Animal agriculture accounts for most of the water consumed in this country, emits two-thirds of the world's acid-rain-causing ammonia, and it the world's largest source of water pollution--killing entire river and marine ecosystems, destroying coral reefs, and of course, making people sick. Try to imagine the prodigious volumes of manure churned out by modern American farms: 5 million tons a day, more than a hundred times that of the human population, and far more than our land can possibly absorb."
I'm not going to try to convert you. But please, go read the full article here. A little reading is going to hurt you.