Is Livestock Causing Climate Change?

Defending Agriculture

New FAO report says livestock sector is major cause of greenhouse gas.

Published on: October 7, 2013

"Livestock matters to climate change. The sector contributes 7.1 gigatonnes (giga=billion) CO2-eq (equivalent) to global anthropogenic GHG emissions – a contribution that can be readily reduced by up to one-third – placing the sector as an integral part of any solution to climate change."  FAO Report Rome, 2013

Once again, the United Nations Food and Agricultural Organization (FAO) has weighed in against agriculture and livestock. The 115-page FAO report entitled "Tackling Climate Change Through Livestock" was released September 26, 2013. 

The report was written by several people including Dr. Pierre Gerber, a PhD. from the Swiss Federal Institute of Technology in Zurich, Switzerland.

Harshly criticized

Gerber has on occasion been harshly criticized by University of California professor Dr. Frank Mitloehner, who has stated Gerber's prior work is "Simply not scientifically accurate to blame livestock for climate change."

Gerber told the BBC in an interview and was quoted as saying he "accepted the criticism."

Notwithstanding these facts, Gerber and his team now say that "The global livestock sector contributes a significant share to anthropogenic GHG emissions, but it can also deliver a significant share of the necessary mitigation effort."

FAO claims livestock emissions represent 14.5% of human-induced global warming emissions. In an earlier publication Gerber claimed livestock contributed 18% of human-induced emissions.

In Chapter 1, FAO declares that the livestock sector is a large user of natural resources and it needs to address its environmental footprint.

The report is based on a newly developed Global Livestock Environment Assessment Model (GLEAM). This model claims to take into account geographical patterns of soil in the world and the major livestock species grown in the world such as buffalo, cattle, goats, pigs and poultry.

The model measures three GHGs emitted from food and agricultural activities: methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2). Page six of the report notes that GLEAM is built on five modules: the herd module, feed module, manure module, system module and allocation module.

The model allegedly considers all sources of emissions along the livestock supply chain. Of the 7.1 billion tons of CO2-eq per year emitted by worldwide livestock, the report claims that 4.6 billion tons of GHGs (65%) come from cattle and dairy; beef is slightly more than dairy by comparison. Global emissions from hogs are estimated at 668 million tons and poultry at 612 million tons.

The report does show that a large portion of animal emissions are from Latin America, the Caribbean and Southeast Asia.

The report reviews techniques and practices to mitigate emissions. "Diet manipulation and feed additives have been identified as the main avenues for the mitigation of enteric CH4 (methane) production." FAO explains diet also affects manure emissions by altering the content of the manure and urine. On p. 48, the FAO in Table A lists feed additives, forage quality, grazing management, macro-supplementation and micro-supplementation as available techniques and practices.

Of course, FAO has available techniques for grazing, housing, manure treatment, manure storage, and manure application. In Chapter six of the report, it concludes that the mitigation techniques identified by Reduced emissions

FAO can result in large environmental benefits and in fact can result in reducing emissions from 14-41% in the ruminant and pig production systems in Asia, Latin America and Africa. FAO does admit that dairy systems in Europe and the U.S. have already demonstrated high levels of productivity, but the emissions can still be reduced by 14-17% or 54-66 million tons of CO2-eq with more improved management systems, feed supplementation and energy saving equipment.

To put livestock's contribution in some rough perspective I checked several sources as to CO2 emissions. There seems to be agreement that forest fires release over 400 billion tons of CO2 every year. (There is, apparently, no FAO concern about stopping this emission!)

Manmade activities worldwide are in the range of 29 billion tons per year. As a nation, the United States emits approximately 6 billion tons of CO2 and China over 6 billion tons. Germany, for example, is listed at approximately 800 million tons.

The FAO report is likely to be controversial. It remains to be seen whether FAO is correct when another author of the report claims "livestock are one of the most significant contributors to today's serious environmental problems."

Is FAO correct or Dr. Mitloehner, who claims it is simply not accurate to blame livestock for climate change?