Livestock's Long Shadow - Questions About Methodology

Questions About Methodology

Meat industry sources object to the methodology used in the UN report, notably that deforestation for livestock was included in the calculations. These sources point out that pasture-grass-feeding, such as is common in New Zealand, may lead to lower emissions attributable to livestock, despite the fact that methane and nitrous oxide from livestock make up half of New Zealand's greenhouse gas emissions. A study in the Journal of Animal Science comparing the methane emissions from grazing and feedlot cattle concluded that grass-fed cattle produce about 4 times more methane than grain-fed cattle. "These measurements clearly document higher CH₄ production (about four times) for cattle receiving low-quality, high-fiber diets than for cattle fed high-grain diets."

An April 2008 inventory report of emissions in the United States, by the United States Environmental Protection Agency found "In 2006, emissions sources contained within the Agricultural Chapters were responsible for emissions of … 6 percent of total U.S. greenhouse gas emissions." The Agricultural Chapters contained topics such as rice production, enteric fermentation in domestic livestock, livestock manure management, and agricultural soil management, but omitted fuel combustion, agricultural CO₂ fluxes, and other land use changes. These were placed separately into the Energy chapter, Land Use, Land-Use Change chapter, and Forestry Chapter. This is also true in the US EPA's 2009 Draft U.S. Greenhouse Gas Inventory Report.