Global warming has been linked to greenhouse gas (GHG) emissions. Swine operations are important sources of GHG, primarily methane (CH4) and nitrous oxide (N2O). The Intergovernmental Panel on Climate Change (IPCC) has developed guidelines for estimating and reporting emissions of GHG (IPCC, 2006). On April 10, 2009, the United States Environmental Protection Agency (EPA) published proposed Mandatory Greenhouse Gas Reporting Rules in the Federal Register (EPA, 2009). The proposed rule relied primarily on the 2006 IPCC Guidelines to calculate GHG emissions from manure storage facilities. The methodology proposed by the IPCC is relatively crude. Estimates of GHG emissions, to a large extent, are based on expert judgments of the IPCC Expert Group. There are concerns as to whether the IPCC and the United States EPA approaches adequately capture the variation that exists in swine operations practiced in North America and Europe. There is also a need to better understand the factors influencing the variation of emissions. Meta-analysis is a quantitative statistical analysis of a large collection of results from different individual studies to identify patterns among study results. Research on GHG emissions from swine operations has been published, providing an opportunity for a meta-analysis.
The objective of this study was to evaluate the effectiveness of the IPCC approaches in estimating CH4 and N2O emissions from swine operation and to investigate the causes of variations in the reported emissions.