By Motavalli, Jim
E Magazine , Vol. 19, No. 4
Atmospheric Carbon Dioxide--Causes of
Livestock Industry--Production Management
Livestock Industry--Environmental Aspects
Livestock Industry--Waste Management
Animal Wastes--Environmental Aspects
Environmental Degradation--United States
Environmental Degradation--Causes of
Ask most Americans about what causes global warming, and they'll point to a coal plant smokestack or a car's tailpipe. They're right, of course, but perhaps two other images should be granted similarly iconic status: the front and rear ends of a cow. According to a little-known 2006 United Nations report entitled "Livestock's Long Shadow," livestock is a major player in climate change, accounting for 18 percent of all greenhouse gas emissions (measured in carbon dioxide equivalents). That's more than the entire transportation system! Unfortunately, this incredibly important revelation has received only limited attention in the media.
How could methane from cows, goats, sheep and other livestock have such a huge impact? As Chris Goodall points out in his book How to Live a Low-Carbon Life (Earthscan Publications), "Ruminant animals [chewing a cud], such as cows and sheep, produce methane as a result of the digestive process ... Dairy cows are particularly important sources of methane because of the volume of food, both grass and processed material, that they eat."
According to the U.S. Department of Agriculture (USDA), the American meat industry produces more than 60 million tons of waste annually--five tons for every U.S. citizen and 130 times the volume of human waste. Michael Jacobson, the longtime executive director of the Center for Science in the Public Interest, adds the fact that just one midsized feedlot churns out half a million pounds of manure each day. "The methane that cattle and their manure produce has a global warming effect equal to that of 33 million automobiles," the Center reports in its book Six Arguments for a Greener Diet.
That's just one side effect of raising animals for food. It turns out that nearly every aspect of the huge international meat trade has an environmental or health consequence, with global warming at the top of the list. If you never thought that eating meat was an environmental (and by extension, political) issue, now is the time to rethink that position.
A Really Big Enterprise
To understand livestock's impact on the planet, you have to consider the size of the industry. It is the single largest human-related use of land. Grazing occupies an incredible 26 percent of the ice- and water-free surface of the planet Earth. The area devoted to growing crops to feed those animals amounts to 33 percent of arable land. Meat production is a major factor in deforestation as well, and grazing now occupies 70 percent of previously forested land in the Amazon region. In Brazil, 60 to 70 percent of rainforest destruction is caused by clearing for animal pasture, one reason why livestock accounts for nine percent of human-caused carbon dioxide (CO2) emissions. Other sources of CO2 include the burning of diesel fuel to operate farm machinery and the fossil fuels used to keep barns warm during the winter.
And food grown for animals could be feeding people. Raising livestock consumes 90 percent of the soy crop in the U.S., 80 percent of its corn and 70 percent of its grain. David Pimentel, professor of entomology at Cornell, points out that "if all the grain currently fed to livestock in the U.S. was consumed directly by people, the number who could be fed is nearly 800 million."
Grazing is itself environmentally destructive. The UN reports that 20 percent of the world's pastures and rangelands have been at least somewhat degraded through overgrazing, soil compaction and erosion.
Methane (a global warming gas 23 times more potent than CO2) comes from many human sources, but livestock account for an incredible 37 percent of that total. Nitrous oxide is also a very powerful global warming gas (296 times more potent than CO2) and by far the biggest source, 64 percent, originates (as does animal-based methane) from manure "off-gassing." This process of nitrous creation is aggravated by intensive factory farming methods, because manure is a more dangerous emitter when it is concentrated and stored in compacted form. …