Livestock’s Long Shadow: Environmental Issues and Options is a United Nations report, released by the Food and Agriculture Organization of the United Nations (FAO) on 29 November 2006, that “aims to assess the full impact of the livestock sector on environmental problems, along with potential technical and policy approaches to mitigation”
The assessment was based on the most recent and complete data available, taking into account direct impacts, along with the impacts of feed crop agriculture required for livestock production. The report states that the livestock sector is one of the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global. The findings of this report suggest that it should be a major policy focus when dealing with problems of land degradation, climate change and air pollution, water shortage and water pollution, and loss of biodiversity.
Based on this report, senior U.N. Food and Agriculture Organization official Dr. Henning Steinfeld stated that the meat industry is “one of the most significant contributors to today’s most serious environmental problems” and that “urgent action is required to remedy the situation.”
Following a Life Cycle Analysis approach, the report evaluates “that livestock are responsible for 18 percent of greenhouse gas emissions, a bigger share than that of transport.”. GHG emissions arise from feed production (e.g. chemical fertilizer production, deforestation for pasture and feed crops, cultivation of feed crops, feed transport and soil organic matter losses in pastures and feed crops), animal production (e.g. enteric fermentation and methane and nitrous oxide emissions from manure) and as a result of the transportation of animal products. Following this approach the report estimates that livestock contributes to about 9% of total anthropogenic carbon dioxide emissions, but 37% of methane and 65% of nitrous oxide emissions. Along the animal food chain, main sources of emissions are:
- Land use and land use change: 2.5 Giga tonnes CO2 equivalent; including forest and other natural vegetation replaced by pasture and feed crop in the Neotropics (CO2) and carbon release from soils such as pasture and arable land dedicated to feed production (CO2)
- Feed Production (except carbon released from soil): 0.4 Giga tonnes CO2 equivalent, including fossil fuel used in manufacturing chemical fertilizer for feed crops (CO2) and chemical fertilizer application on feedcrops and leguminous feed crop (N2O, NH3)
- Animal production: 1.9 Giga tonnes CO2 equivalent, including enteric fermentation from ruminants (CH4) and on-farm fossil fuel use (CO2)
- Manure Management: 2.2 Giga tonnes CO2 equivalent, mainly through manure storage, application and deposition (CH4, N2O, NH3)
- Processing and international transport: 0.03 Giga tonnes CO2 equivalent
In March 2010, a newspaper reported that an unnamed American scientist had convinced one of the authors of the report that the report’s comparison of the relative magnitude of emissions from transportation versus the meat production industry was flawed, because it was based on different calculations of each sector’s emissions: “The meat figure had been reached by adding all greenhouse-gas emissions associated with meat production, including fertilizer production, land clearance, methane emissions, and vehicle use on farms, whereas the transport figure had only included the burning of fossil fuels.”
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. Contrary to this assumption, however, 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.“ Subsequent studies have supported this conclusion.
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.
In a 2009 issue of the Worldwatch Institute magazine, environmental assessment specialists Robert Goodland and Jeff Anhang argued in Livestock and Climate Change that the FAO vastly underestimated the environmental impact of the livestock sector and that it accounts for at least 51% of global GHG emissions. Some criticisms included the FAO’s use of the 100-year global-warming potential (GWP) of CH4 rather than the 20 GWP favored by Goodland and Anhang. However, Goodland and Anhang continue to use the 100-year GWP for anthropogenic greenhouse gases in their analysis, with the sole exception of methane emissions from livestock. More controversially, Goodland and Anhang argue that animal respiration should be included, despite widely adopted conventions that they be treated as part of short-term carbon cycle and excluded. The report was well received by the FAO and has been cited by several UN agencies and international institutions. Despite that, some criticism on Livestock and Climate Change was received including from within the FAO.