EPA publishes annual greenhouse gas inventory
- Last Updated on Thursday, 17 April 2014 08:23
- Written by Saige Albert
The 19th edition of the annual Environmental Protection Agency (EPA) Inventory of U.S. Greenhouse Gas Emissions and Sinks (Inventory) showed a 3.4 percent decrease in greenhouse gas emissions in 2012 compared to 2011. The report provides an overview of greenhouse gas emissions in the United States since 1990.
The Inventory, which is based on the emission of the six main greenhouse gases including carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride, also found a 10 percent decrease in emissions in 2012 compared to 2005 levels.
The largest source of greenhouse gas emissions in the United States was carbon dioxide, accounting for approximately 82.5 percent of total greenhouse gas emissions. Methane emissions, which the report says are down nearly 11 percent since 1990, were the second largest contributor to greenhouse gas emissions, accounting for 9 percent of total emissions in 2012.
According to the report, the primary sources for greenhouse gas emissions in the United States were electricity production (32 percent), transportation (28 percent), industry (20 percent), commercial and residential (10 percent), and agriculture (9 percent). Land use and forestry offset 15 percent of greenhouse gas emissions in 2012, the report says.
With regard to agriculture specifically, nitrous oxide emissions from farming practices such as fertilizer application and other cropping practices, manure management, and field burning of agricultural residues accounted for 62 percent of agricultural emissions.
Methane emissions represented approximately 38 percent of total agriculture emissions. The report says beef and dairy cattle were the largest methane emitters. From 1990 to 2012, total methane emissions from enteric fermentation have increased 2.3 percent. With regard to beef cattle, emissions increased just 0.6 percent from 1990 to 2012. The report found that while emissions increased slightly, the cattle population dropped 5 percent but production increased 14 percent. Likewise, while dairy emissions increased 6 percent, the population declined by 2 percent but milk production increased 36 percent. EPA says this indicates that emission factors per unit of product are decreasing.
Manure management was the other primary contributor to methane emissions, contributing 9.4 percent. According to the report, emissions from manure increased 68 percent from 1990 to 2012, with the majority of the increase coming from swine and dairy cow manure. However, from 2011 to 2012, there was only a 1.7 percent increase in methane emissions from manure due partly to the effects of manure management systems.
The report is submitted annually to the United Nations.
- Article is courtesy of Drover's CattleNetwork