GHG Emissions Takeaways
Takeaways are key points detailed and referenced in the Greenhouse Gas Emissions section
Animal Ag Overview
Animal ag’s share of total U.S. greenhouse gas emissions is often viewed as “small.” This is because:
Animal ag’s share is generally given as a percentage of total U.S. emissions, which per capita is ~2.5 times the world average. Animal ag’s emissions are “small” only in relation to our nation’s high overall levels.
The EPA does not explicitly acknowledge that emissions due to grazing are attributable to livestock and does not examine the role of feed crops.
By international protocol, there are many factors not included in U.S. “agricultural emissions,” so they are not typically attributed to livestock. Among items not included are on-farm electric and fuel usage, production of chemical fertilizers, pesticides and other inputs for feed crops, feed processing and transportation, animal transit and slaughter, and land use change.
Understanding the outsized U.S. share of global historical (cumulative) contributions puts U.S. current contributions in a clearer perspective.
U.S. Share of Total GHG Emissions
The U.S. is responsible for the largest share of cumulative GHG emissions. Through 2021, the U.S. generated ~17% of historical global emissions.
On a per capita basis, the U.S. has added to total cumulative emissions at about 4 times the world average, 6 times China’s average, and 15 times that of India.
The U.S. current share of global annual emissions is ~11%, while China’s share is ~29%.
Agricultural Emissions
In the U.S., emissions from on-farm agriculture are 9.4% of total U.S. emissions (~10% including on-farm fuel and electric use).
The 2 largest sources of agricultural emissions are:
– N2O from chemical fertilizers and manure applied to crops and grazing land, and
– CH4 from enteric fermentation and the handling of manure on factory farms.
Animal Ag Emissions
About 5.7% of total U.S. emissions can be directly attributed to animal ag when taking into account enteric fermentation, manure management, and grazing lands (and not including feed crops).
Broadly estimated, ~7.4% of total U.S. emissions can be attributed to animal ag when adding emissions from feed crops.
U.S. animal ag emissions are equal to ~47% of the total per capita emissions of India.
About 79% of total agricultural emissions are from animal ag: enteric fermentation at 32%, feed crops at 18%, grazing at 15%, and manure management at 14%.