Producing meat has a huger environmental impact than what it has been supposed so far: at least half of all human-caused greenhouse gases (GHGs) are generated by lifecycle and supply chain of animals raised for food, say Robert Goodland and Jeff Anhang in their survey "Livestock and Climate Change", in the latest issue of World Watch magazine.

According to a 2006 report by the United Nations Food and Agriculture Organization, Livestock's Long Shadow, 18 percent of annual worldwide GHG emissions can be attributed to cattle, buffalo, sheep, goats, camels, pigs, and poultry. But recent analysis by Goodland and Anhang reverse this figure, as it finds that livestock and their byproducts actually account for at least 32.6 billion tons of carbon dioxide per year, that is 51 percent of annual global GHG emissions.

Reviewing both direct and indirect sources of GHG emissions from livestock, the study reveals that certain emissions sources have been both underestimated and overlooked by previous calculations, which 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."