Measuring Livestock Contributions To Greenhouse Gas Emissions

f7a06-cattleDuring recent years, activists have taken to placing blame for increasing greenhouse gas (GHG) emissions on livestock farming. Claims are that beef and dairy cattle, swine and poultry are greater contributors to increasing GHG levels than transportation. A frequently cited source of these claims are documentary projects like Cowspiracy and Food Inc.

As we approach the need for growing global food demand, specifically for protein by growing middle class populations, with less land and greater pressure to use fewer inputs, we need to utilize technologies to improve our efficiencies – growing food with fewer resources. Animal agriculture, especially in developed countries, has significantly decreased negative impacts on the environment (such as GHG emissions and water use) and improved our sustainability in the process.

While many people tend to focus on the negatives of resource consumption, they overlook the positive contributions of animal agriculture – maintaining open lands that turn atmospheric carbon into oxygen, retaining lands for wildlife habitat, keeping headwater sources clean and kept away from suburban development.

A professor from the University of California at Davis recently took on these claims by summarizing studies and measurements from the EPA and FAO to look at the contributions to GHG emissions from livestock compared to the transportation industry. His conclusions are shared in a white paper (available here) and I have shared a few highlights below.

Livestock’s Contributions to Climate Change: Facts and Fiction

Highlights from white paper by Dr. Frank Mitloehner, Professor & Air Quality Specialist, Department of Animal Science, University of California, Davis

When divorcing political fiction from scientific facts around the quantification of GHG from all sectors of society, one finds a different picture. Leading scientists throughout the U.S., as well as the U.S. Environmental Protection Agency (EPA) have quantified the impacts of livestock production in the U.S., which accounts for 4.2% of all GHG emissions, very far from the 18% to 51% range that advocates often cite. Comparing the 4.2% GHG contribution from livestock to the 27% from the transportation sector, or 31% from the energy sector in the U.S. brings all contributions to GHG into perspective.

Comparison of greenhouse gas emissions between industries in the U.S. - Mitloehner
Comparison of greenhouse gas emissions between industries in the U.S. – Image via Mitloehner

It is sometimes difficult to put these percentages in perspective, however; if all U.S. Americans practiced Meatless Mondays, we would reduce the U.S. national GHG emissions by 0.6%. A beefless Monday per week would cut total emissions by 0.3% annually. One certainly cannot neglect emissions from the livestock sector but to compare them to the main emission sources would put us on a wrong path to solutions, namely to significantly reduce our anthropogenic carbon footprint to reduce climate change.

In spite of the relatively low contributions to total GHG emissions, the U.S. livestock sector has shown considerable progress during the last six plus decades, and commitment into the future, to continually reduce its environmental footprint, while providing food security at home and abroad. These environmental advances have been the result of continued research and advances in animal genetics, precision nutrition, as well as animal care and health.

Increased efficiency in raising cattle in the U.S. over the past several decades thanks to better management practices and understanding of cattle needs.  - Mitloehner
Increased efficiency in raising cattle in the U.S. over the past several decades thanks to better management practices and understanding of cattle needs. – Image via Mitloehner

Globally, the U.S. livestock sector is the country with the relatively lowest carbon footprint per unit of livestock product produced (i.e. meat, milk, or egg). The reason for this achievement largely lies in the production efficiencies of these commodities, whereby fewer animals are needed to produce a given quantity of animal protein food, as the following milk production example demonstrates: the average dairy cow in the U.S. produces 22,248 lbs. milk/cow/year. In comparison, the average dairy cow in Mexico produces 10,500 lbs. milk/cow/year, thus it requires 2-plus cows in = 2x Mexico to produce the same amount of milk as one cow in the U.S. India’s average milk production per cow is 2,500 lbs. milk/cow/year, increasing the methane and manure production by a factor of 9 times compared to the U.S. cow. As a result, the GHG production for that same amount of milk is much lower for the U.S. versus the Mexican or Indian cow. Production efficiency is a critical factor in sustainable animal protein production and it varies drastically by region.

Improvements in livestock production efficiencies are directly related to reductions of the environmental impact. Production efficiencies and GHG emissions are inversely related—when the one rises, the other falls. Our natural resources of land, water and minerals (fertilizer) necessary for agricultural production, have not grown but in fact decreased. As a result, agriculture will have to become much more efficient worldwide and engage in an efficient path similar to the one it has traveled down in U.S. livestock production in recent decades.

The U.S. livestock, poultry and feed industries are one of the most efficient and lowest environmental impact systems in the world. The research, technologies and best practices that have been developed and implemented over time in the U.S. can also be shared with other production regions around the world.

The livestock sector is committed to continuous improvement of their environmental impact in North America, and to doing its part in transferring knowledge, technologies and best practices to enhance global environmental livestock impact by region. Now is the time to end the rhetoric and separate facts from fiction around the numerous sectors that contribute emissions and to identify solutions for the global food supply that allow us to reduce our impact on the planet and its resources.

Read the full white paper with omitted sections and additional citations here. For more dialogue and examples of environmental impacts from livestock farming, visit this blog by Dr. Jude Capper, the EPA resource on Sources of Greenhouse Gas Emissions or the Livestock Environmental Assessment and Performance page from FAO.

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