Perspectives of the impacts of livestock production on climate change

Abstract

Life cycle assessment for livestock: a complex issue Discussions about global climate change have spurred evaluations of livestock agriculture’s contribution; however, the complexity and variation in livestock production systems makes the quantification of greenhouse gas (GHG) emissions difficult. Several recent publications have used Life Cycle Assessments (LCAs) that employ ‘cradle-to-the-grave’ accounting of GHGs from inputs and outputs over the entire livestock production chain. An LCA for dairy and beef production can include the GHGs produced from the production of forages and grains (emissions from the soil, fertilizer and burning fossil fuels), from the cattle directly (emissions from manure and feed fermentation in the rumen) and from processing and transporting the beef or dairy products to the consumer (emissions from burning fossil fuels and refrigeration). The sum of the GHGs from all of these sources would be considered the total ‘life cycle’ emissions or carbon footprint for livestock production. The application and comparisons between these existing LCAs can be limited because of differences in their scope and scale. Reporting GHG missions per unit of production (e.g. per kg of beef, or liter of milk) can clarify some of the discrepancies and allow for comparisons across current production systems or comparisons of current v. historical livestock production.