Don't Blame Cows for Climate Change

Given all the discussion about the effect that greenhouse gas (GHG) emissions have on worldwide climate and the debates about ways to limit climate change, many have been asking, “What is the role of animal agriculture as a source of greenhouse gases?” Some publications and media commentary have identified livestock production as a leading source of greenhouse gases, including a 2006 United Nations (UN) report, Livestock’s Long Shadow.

Printed in the report’s executive summary and nowhere else in the body of the report are two sentences that read: “The livestock sector is a major player, responsible for 18 percent of greenhouse gas emissions measured in CO2e [carbon dioxide equivalents]. This is a higher share than transport.” According to University of California (UC)-Davis associate professor and air quality specialist Frank Mitloehner, those statements are not accurate, yet their wide distribution through the news media has put Americans and others on the wrong path toward solutions.

Mitloehner said leading authorities agree that, in the United States, raising cattle and pigs for food accounts for about three percent of all GHGs, while transportation creates an estimated 26 percent. He noted that the UN report produced its numbers for the livestock sector by adding up emissions from farm to table, including the gases produced by growing animal feed, animals’ digestive emissions, and processing meat and milk into foods. But the report’s transportation analysis did not similarly add up emissions from well to wheel; instead, it considered only emissions from fossil fuels burned while driving.

“This lopsided ‘analysis’ is a classical apples-and-oranges analogy that truly confused the issue,” Mitloehner stated. It appears the UN has heard Mitloehner’s criticism.

“I must say honestly that he has a point,” Pierre Gerber, a policy officer with the UN’s Food and Agriculture Organization (FAO) and one of the report’s authors, told the BBC. “We factored in everything for meat emissions, and we didn’t do the same thing with transport. But on the rest of the report, I don’t think it was really challenged.” Gerber revealed that a revised report on the impact of the livestock industry should be available by the end of 2010.

Mitloehner’s analysis on the flawed data in the UN report is presented in a study, titled Clearing the Air: Livestock’s Contributions to Climate Change, published in October 2009 in the peer-reviewed journal Advances in Agronomy. Co-authors of the paper are UC Davis researchers Maurice Piteskey and Kimberly Stackhouse.

Clearing the Air is a synthesis of research by the UC Davis authors and many other institutions, including the FAO, U.S. Environmental Protection Agency, U.S. Department of Agriculture, California Environmental Protection Agency, and the California Air Resources Board. Writing the synthesis was supported by a grant from the Beef Checkoff Program. The study has been cited in numerous media outlets worldwide since being released and was the main topic of discussion during a June 2010 Webinar held through the Livestock and Poultry Environmental Learning Center. Joining Mitloehner was Rick Stowell, University of Nebraska-Lincoln, who focused on “Trends in Agricultural Greenhouse Gas Production: U.S. and Canada.” The Webinar and presentations are available at

Report Focuses on Dairy Emissions
In a separate report released in April 2010, Greenhouse Gas Emissions from the Dairy Sector, FAO states dairies account for around four percent of all global anthropogenic GHG emissions, a figure that includes emissions associated with the production, processing, and transportation of milk products as well as emissions related to meat produced from animals originating from dairies.

Global milk production, processing, and transportation contributes 2.7 percent of global anthropogenic GHG emissions, while meat production from dairy cows and non-milk producing dairy calves is responsible for 1.3 percent of emissions. Dairies in the industrialized nations of North America, Europe, and Australia/New Zealand have the lowest GHG emissions, with North America lowest of all. Dairies in Central and South America and part of Asia produce three to four times the emissions of North American dairies, while dairies in Sub-Saharan Africa produce up to seven times more GHG emissions.

According to FAO, in 2007, the dairy sector emitted 1.969 billion metric tons of CO2e, of which 1.328 billion metric tons are attributed to milk, 151 million metric tons to meat from culled dairy animals, and 490 million metric tons to calves from the dairy sector that were raised for meat. Methane contributes most to the impact of milk on climate change, accounting for about 52 percent of the GHG emissions in both developed and developing countries. Nitrous oxide emissions account for 27 percent of GHGs in developed countries and 38 percent in developing countries. CO2 accounts for a higher share of emissions in developed countries (21 percent) than in developing countries (10 percent).

The FAO report covers all major milk production systems from nomadic herds to intensified dairy operations. It focuses on the entire dairy food chain, including the production and transport of inputs (fertilizer, pesticides, and feed) used for dairy farming, on-farm emissions, and emissions associated with milk processing and packaging as well as transporting milk products to retailers.

The assessment is part of an ongoing FAO program to analyze and recommend options for climate change mitigation. The next step is to use a similar approach to quantify GHG emissions associated with other major livestock species. FAO expects a final report out in 2011.

Newsline – August 2010 RENDER | back