According to a recent comprehensive study by the United Nations Food and Agriculture Organization, agriculture currently contributes 18% of total world greenhouse gas emissions and livestock production accounts for nearly 80% of this (Livestock’s Long Shadow: Environmental Issues and Options, Rome: 2006, p. 112). According to the Intergovernmental Panel on Climate Change 4th Assessment Report, greenhouse gas emissions in 2004 were 49 billion tons CO2 equivalent. 18% of 49 billion tons CO2 equivalent equals 8.82 billion tons CO2 equivalent. Since each 1 ton of carbon equals 3.67 tons of CO2, 8.82 billion tons CO2 equivalent equals 2.38 billion tons carbon equivalent.
Thus meat-eating contributes approximately 2.38 billion tons carbon equivalent to current greenhouse gas emissions (substituting more recent figures for world carbon emissions would push this number up, perhaps over 2 and ½ billion tons). The U.N. Food and Agricultural Organization projects a worldwide doubling in animal production between 2000 and 2050, from 60 billion to 120 billion animals raised annually, which under “business as usual,” will double the greenhouse gas emissions from this sector to 4.76 billion tons. If instead we hold worldwide animal food production steady over the next fifty years, this would provide nearly two and a half carbon wedges (averting a 2.38 billion tons increase). Merely preventing half the projected doubling during that time would supply more than one full carbon wedge (1.19 billion tons averted) (see Gidon Eshel and Pamela Martin, “Diet, Energy, and Global Warming,” Earth Interactions, 10 (2006), paper number nine).
Such veggie wedges might be accomplished non-coercively by increasing the price of meat, removing subsidies for cattle production, banning confined animal feedlot operations (CAFO’s) as the European Union is in process of doing, and directly taxing meat to discourage consumption. These measures could accommodate a reasonable increase in meat-eating in poor countries where many people eat little meat, while providing environmental and health benefits in wealthy countries where people eat more meat than is good for them (Philip Cafaro, Richard Primack and Robert Zimdahl, “The Fat of the Land: Linking American Food Overconsumption, Obesity, and Biodiversity Loss,” Journal of Agricultural and Environmental Ethics, 19 (2006), 541–561). They could complement efforts to improve the conditions under which food animals are raised, changes that may be expensive, but which are arguably demanded by morality anyway.
Several caveats are in order. In some parts of the world, increased meat-eating may represent a real nutritional improvement in people’s diets (parts of Asia). In some areas, meat-eating has not increased at all in recent decades and future increases might may represent a real nutritional improvement in people’s diets (sub-Saharan Africa). In other areas, however, such as the United States, meat-eating should be cut back for human health reasons.
For these reasons, worldwide efforts should emphasize getting over-consumers of meat and animal products to cut back. They should also teach people in countries that are becoming more wealthy the nutritional and health value of their traditional diets. For a detailed discussion of the meat/heat connection, see Global Warning: Climate Change and Farm Animal Welfare from Compassion in World Farming (http://www.fao.org/fileadmin/user_upload/animalwelfare/GlobalWarningExecutiveSummary1.pdf).
Former IPCC Chairman Rajendra Pachauri is a proponent of eating less meat to fight climate change. On September 19, 2008, Pachauri, a vegetarian himself, posted the following message to his blog at rkpachauri.org:
Lifestyle Changes for A Healthy Planet
During the past few weeks I have spoken in public on the benefits of lower consumption of meat as a means to reduce the emissions of greenhouse gases (GHGs). As would be expected I have, as a result, received some comments that are positive and others which amount to strong criticism. My purpose in raising this issue was only to create a debate on the subject. The Synthesis Report which is part of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) clearly stated, "There is also high agreement and medium evidence that changes in lifestyle and behaviour patterns can contribute to climate change mitigation across all sectors. Management practices can also have a positive role." In my view an important component of lifestyle changes relates to changes in diet which in actual fact may bring about an improvement in human health. In the case of meat consumption there are benefits not only to the individual who reduces consumption of meat but clear advantages in terms of reducing GHG emissions.