My first post on the effect of eating meat on the environment provoked quite a bit of discussion, so in honor of Earth Day, I thought I should follow up with more information about how our natural resources (e.g., air, water, and soil) are depleted and devastated by animal agriculture.

Of course, Earth Day is also a good time to remember that animal agriculture only exists at these levels because people are purchasing vast quantities of chicken, beef, pork, and fish. The market for meat (i.e., we, the consumers) drives the depletion and destruction.

* Excrement produced by chickens, pigs, and other farm animals: 16.6 billion tons per year – more than a million pounds per second (that’s 60 times as much as is produced by the world’s human population – farmed animals produce more waste in one day than the U.S. human population produces in 3½ years). This excrement is a major cause of air and water pollution. According to the United Nations: “The livestock sector is… the largest sectoral source of water pollution, contributing to eutrophication, ‘dead’ zones in coastal areas, degradation of coral reefs, human health problems, emergence of antibiotic resistance and many others.”

* Water used for farmed animals and irrigating feed crops: 240 trillion gallons per year- 7.5 million gallons per second (that’s enough for every human to take 8 showers a day, or as much as is used by Europe, Africa, and South America combined). According to the UN: “[t]he water used by the sector exceeds 8 percent of the global human water use.” As just one example, “[O]n average 990 litres of water are required to produce one litre of milk.” So drinking milk instead of tap water requires almost 1,000 times as much water.

* Emissions of greenhouse gases from raising animals for food: The equivalent of 7.8 billion tons of carbon dioxide per year, according to the UN report. Concludes the UN: “The livestock sector is… responsible for 18% of greenhouse gas emissions.” That’s about 40 percent more than all the cars, trucks, planes, trains, and ships in the world combined (transport is 13%). And “The sector emits 37% of anthropogenic methane (with 23 times the global warming potential–or GWP–of CO2)… It emits 65% of anthropogenic nitrous oxide (with 296 times the GWP of CO2). These figures are based on the power of these gases over 100 years; in fact, over 20 years–a more important timeframe for dealing with global warming–methane and nitrous oxide are 72 times and 289 times more warming than CO2. And Dr. Rajendra Pachauri, Chair of the IPCC (which shared the Nobel Peace Prize with Al Gore) has been saying that the 18% figure is probably an underestimate.

* It takes more than 11 times as much fossil fuel to make one calorie of animal protein as it does to make one calorie of plant protein.

* Soil erosion due to growing livestock feed: 40 billion tons per year (or 6 tons/year for every human being on the planet–of course if you don’t eat meat, none of this is attributed to you; if you’re in the U.S. where we eat lots more meat than most of the world, your contribution is many times greater than 6 tons/year). About 60% of soil that is washed away ends up in rivers, streams and lakes, making waterways more prone to flooding and to contamination from soil’s fertilizers and pesticides. Erosion increases the amount of dust carried by wind, polluting the air and carrying infection and disease.

* Land used to raise animals for food: 10 billion acres. According to the UN: “In all, livestock production accounts for 70 percent of all agricultural land and 30 percent of the land surface of the planet.” And “70 percent of previous forested land in the Amazon is occupied by pastures, and feedcrops cover a large part of the remainder.” And “About 20 percent of the world’s pastures and rangelands, with 73 percent of rangelands in dry areas, have been degraded to some extent, mostly through overgrazing, compaction and erosion created by livestock action.”

* According to the UN, animal agriculture is a leading case of water pollution. The main water pollutants in the US are sediments and nutrients. Animal agriculture is responsible for 55 percent of the erosion that causes sedimentation, and for a third of the main nutrient pollutants, nitrogen and phosphorous. On top of that, animal agriculture is the source of more than a third of the United States’ water pollution from pesticides, and half of its water pollution from antibiotics.

* Livestock are also responsible for almost two-thirds of anthropogenic ammonia emissions, which contribute significantly to acid rain and acidification of ecosystems.

* Grain and corn raised for livestock feed that could otherwise feed people, according to the UN: 836 million tons per year (note that the more commonly used figure, 758 million tons, is metric). That’s more than 7 times the amount used for biofuels and is much more than enough to adequately feed the 1.4 billion humans who are living in dire poverty, and the number doesn’t even include the fact that almost all of the global soy crop (about 240 million tons of soy) is also fed to chickens, pigs, and other farmed animals.

* An American saves more global warming pollution by going vegan than by switching their car to a hybrid Prius.

* Razing the Amazon rainforest for pasture and feed crops: 5 million acres of Amazon per year. Former Amazon rainforest converted to raising animals for food since 1970 is more than 90% of all Amazon deforestation since 1970.

* According to the UN: “Indeed, the livestock sector may well be the leading player in the reduction of biodiversity…” And “[l]ivestock now account for about 20 percent of the total terrestrial animal biomass, and the 30 percent of the earth’s land surface that they now pre-empt was once habitat for wildlife.” And “Conservation International has identified 35 global hotspots for biodiversity, characterized by exceptional levels of plant endemism and serious levels of habitat loss. Of these, 23 are reported to be affected by livestock production. An analysis of the authoritative World Conservation Union (IUCN) Red List of Threatened Species shows that most of the world’s threatened species are suffering habitat loss where livestock are a factor.”

United Nations scientists, in their 408-page indictment of the meat industry, sum up these statistics, pointing out that the meat industry is “one of the … most significant contributors to the most serious environmental problems, at every scale from local to global,” including “problems of land degradation, climate change and air pollution, water shortage and water pollution, and loss of biodiversity.”

Perhaps it’s time to explore vegetarianism. Happy Eating!

United Nations statistics and quotes come from the FAO report “Livestock’s Long Shadow.” Other statistics come from the American Journal of Clinical Nutrition (Pimentel & Pimentel, 2003); the World Bank (Marglis, “Causes of Deforestation of the Brazilian Amazon,” 2004); and Earth Interactions Journal (Eshel & Martin, “Diet, Energy, and Global Warming,” 2006). Other non-attributed statistics were calculated by Noam Mohr, a physicist at New York University Polytechnic Institute.