What Greenhouse Gases Are Emitted by Pig Farms?

green stylized pig logoIn 2014, all man-made sources of greenhouse gas (GHG) emissions in the U.S. were estimated to be 6,870.5 MMT CO2e (millions of metric tons carbon dioxide equivalent). Agriculture was estimated to be responsible 8.3% of those emissions (573.6 MMT CO2e per year). When looking specifically at animal agriculture, all different species together emit an estimated 243.4 MMT CO2e/year, which is 3.5% of all U.S. emissions. The pork industry is estimated to have emitted 26.6 MMT CO2e or 0.34%. (Source: US EPA Greenhouse Gas Inventory 2015)

The two areas where the swine industry produced measurable contributions to agricultural emissions include:

  • Enteric fermentation – the release of gases during normal digestion by animals. Pigs release approximately 2.4 MMT CO2e of the of the 164.3 MMT CO2e produced by all livestock and poultry in the U.S.
  • Manure management – pig farms are estimated to  release 24.2 MMT CO2e of the 78.7 MMT CO2e produced by all animal manure systems in 2014.

Manure management is planned using a total system approach. Animal manure management systems involve six basic functions: production, collection, transfer, storage, treatment and utilization.  The first five out of those six make up the manure management number above. Utilization (usually by land application to crop fields) is instead categorized within “Agricultural soil management”. The greenhouse gases emitted from manure systems include methane and nitrous oxide which form as manure decomposes. 

When all of the GHGs emitted during a particular activity or process are added together, it is the carbon footprint.  The standardized procedure to calculate carbon footprints is a life cycle analysis or LCA.  

Related: Carbon Footprint, Life Cycle Analysis and the Pork Industry

For more information:

Authors: Jill Heemstra, University of Nebraska-Lincoln and Rick Fields, University of Arkansas


This information is part of the program “Integrated Resource Management Tool to Mitigate the Carbon Footprint of Swine Produced In the U.S.,” and is supported by Agriculture and Food Research Initiative Competitive Grant no. 2011-68002-30208 from the USDA National Institute of Food and Agriculture. Project website.