How Meat Contributes to Global Warming
An Environmental Article from


Scientific American
March 2009

Producing beef for the table has a surprising environmental cost: it releases prodigious amounts of heat-trapping greenhouse gases

Burgers or Tofu?

Annual beef consumption per capita varies from 120 pounds in Argentina and 92 pounds in the U.S. to only a pound in the small eastern European country of Moldova; the average is about 22 pounds per person per year. The colors of the countries and the distortions of their usual shapes reflect the amount by which beef consumption per capita varies from the world average. World beef consumption per capita is growing, particularly in Asia, because of economic development: as people earn higher incomes, they purchase foods they find more desirable.

Eating and Driving: An Atmospheric Comparison

The greenhouse gas emissions from producing various foods can be appreciated by comparing them with the emissions from a gasoline-powered passenger car that gets 27 miles per gallon. The estimated emissions from food production incorporate the assumption that 1,000 kilograms of carbon per hectare per year (about 2,700 pounds of carbon dioxide per acre per year) would have been absorbed by forests or other vegetation if the land had not been cleared for annual food crops or fodder. Greenhouse gases—carbon dioxide (CO2) and methane, for instance—trap solar energy and warm the earth’s surface. Quantities of greenhouse gases are often expressed as the amount of CO2 that would have the same global-warming potential: their CO2 equivalent.

The High (Greenhouse Gas) Cost of Meat

Worldwide meat production (beef, chicken and pork) emits more atmospheric greenhouse gases than do all forms of global transportation or industrial processes. On the basis of data from the United Nations Food and Agriculture Organization (FAO) and the Emission Database for Global Atmospheric Research, the author estimates that current levels of meat production add nearly 6.5 billion tons of CO2-equivalent greenhouse gases every year to the atmosphere: some 18 percent of the worldwide annual production of 36 billion tons. Only energy production generates more greenhouse gases than does raising livestock for food.

A Growing Appetite

World beef production is increasing at a rate of about 1 percent a year, in part because of population growth but also because of greater per capita demand in many countries. Economic analysis shows that if all beef were produced under the economically efficient feedlot, or CAFO (concentrated animal feeding operation), system—which generates fewer greenhouse emissions than many other common husbandry systems do—beef production by 2030 would still release 1.3 billion tons of CO2-equivalent greenhouse gases. If current projections of beef consumption are correct, even under the feedlot production system the buildup of CO2-equivalent greenhouse gases could amount to 26 billion tons in the next 21 years.

Prime Cuts: How Beef Production Leads to Greenhouse Gases

The largest fraction of the greenhouse effect from beef production comes from the loss of CO2-absorbing trees, grasses and other year-round plant cover on land where the feed crops are grown and harvested. Second most important is the methane given off by animal waste and by the animals themselves as they digest their food. This analysis of the U.S. feedlot beef production system was done by ecological economist Susan Subak, then at the University of East Anglia in England.

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