Holy crap…literally. The environmental impact of the life cycle and supply chain of animals raised for food has been vastly underestimated, and in fact accounts for at least half of all human-caused greenhouse gases (GHGs), according to Robert Goodland and Jeff Anhang, co-authors of “Livestock and Climate Change” (pdf) in the latest issue of World Watch magazine.

A widely cited 2006 report by the United Nations Food and Agriculture Organization, Livestock’s Long Shadow, estimates that 18 percent of annual worldwide GHG emissions (which is more than cars) are attributable to cattle, buffalo, sheep, goats, camels, pigs, and poultry. But recent analysis by Goodland and Anhang finds that livestock and their byproducts actually account for at least 32.6 billion tons of carbon dioxide per year, or 51 percent of annual worldwide GHG emissions.

Reviewing both direct and indirect sources of GHG emissions from livestock, the study finds that previous calculations have both underestimated and overlooked certain emissions sources as well as assigned emissions they deem to be livestock-related to the wrong sectors. The authors locate these discrepancies in previous analyses of livestock respiration, land use, and methane.

Based on their research, Goodland and Anhang conclude that replacing livestock products with soy-based and other alternatives would be the best strategy for reversing climate change. “This approach would have far more rapid effects on GHG emissions and their atmospheric concentrations—and thus on the rate the climate is warming—than actions to replace fossil fuels with renewable energy.”

Basically stop eating meat (and fish) if you really want to make a big change in stopping global warming. It is a simple and easy step you can take that will have far reaching consequences.