Beef production is a major U.S. industry, delivering about 94 million head of cattle with a retail value of $73 billion in 2009 (USDA 2010c). Beef accounts for more global warming emissions in the United States than the production of other foods (Eshel and Martin 2006). This report evaluates the potential for pasture beef producers to curb the industry’s contribution to climate change by adopting better management practices.

A better burger would be no small achievement. U.S. agriculture accounts for about 6 percent of U.S. global warming emissions, according to the U.S. Environmental Protection Agency (EPA 2010). (Like this report,...

U.S. global warming emissions totaled 7,150 million metric tons (MMT) of CO₂ equivalent in 2007 (EPA 2007). Methane emissions from beef cattle digestion total 100.8 MMT of CO₂ equivalent, while methane emissions from manure stored in feedlots and other facilities total 2.5 MMT of CO₂ equivalent (EPA 2010). Methane from beef cattle therefore accounts for about 1.4 percent of U.S. global warming emissions.

The share of nitrous oxide emissions from beef cattle in total U.S. global warming emissions is more difficult to determine. That is because those emissions stem from several sources, some of which are not readily quantified. Here,...

Enteric fermentation accounts for more than 97 percent of methane emissions from beef cattle, while manure management accounts for about 2.5 percent (EPA 2010). Understanding how enteric fermentation and manure produce methane emissions can shed light on farm practices that can reduce those. This chapter provides an overview of methane emissions from beef cattle and possible mitigation practices on pasture and through feeding of harvested forage.

One effective approach to tackling enteric fermentation is to increase the efficiency with which cattle use feed, because more feed is then used to produce meat rather than methane. This approach entails ensuring that...

The average estimate of U.S. agricultural emissions of nitrous oxide grew 7 percent from 1990 to 2008 (EPA 2010). Land managers can make significant cuts in those emissions from pasture-raised beef— in some cases with better economic performance.

Some 92 percent of nitrous oxide emissions from U.S. agriculture come from soils used to grow row crops such as corn and wheat, and range and pasture grasslands (EPA 2010). Both direct and indirect sources—including nitrogen from soil leached into groundwater—produce these emissions.

Estimates of nitrous oxide emissions from U.S. agriculture range from 154 MMT of CO₂ equivalent to 389...

Well-managed pasture soils sequester carbon. Although agriculture in the United States does not produce as much carbon dioxide as methane and nitrous oxide, using soil to sequester carbon can reduce the climate change impact of beef production. This chapter evaluates the factors that influence carbon sequestration rates in pasture.

Sequestration begins with photosynthesis, whereby plants convert carbon dioxide into carbon-containing compounds such as sugars, and then to more complex molecules such as cellulose and lignin. Some of these carbon- containing components eventually return to the soil in the form of plant roots, root exudates, plant residues, and manure produced by...

Feedlots, or CAFOs, are the predominant means of finishing beef in the United States. Comparing the climate impact of CAFOs with that of beef raised entirely on pasture is important, given that some analysts and consumers are calling for a shift to pasture beef finishing, or conversely that CAFO production is being adopted in other parts of the world.

Such a comparison would typically rely on life-cycle models, which would quantify global warming emissions and carbon sequestration from various practices used in each system. However, that approach presents substantial challenges. Conditions on actual farms that affect global warming emissions or...

Pasture and rangeland will continue to be mainstays of beef production because ruminants must consume some forage to stay healthy, and because they can produce high-quality food from low-quality grassland that cannot support crops. Some consumers may also prefer beef produced exclusively on pasture. Developing and implementing practices that reduce the climate impact of pasture beef production is therefore important.

U.S. beef producers can reduce their heat-trapping emissions and increase soil carbon sequestration by using best practices for managing pastures available now. These improved practices will have a small impact on overall U.S. global warming emissions, but will significantly curb...