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Overview of GHG Emissions
Agricultural sector greenhouse gas (GHG) emissions include non-energy methane (CH4)
emissions from livestock (i.e., enteric (intestinal) fermentation), 1 CH4 and nitrous oxide (N2O)
emissions from the storage and treatment of livestock manure (e.g., in compost piles or anaerobic
treatment lagoons),2 N2O emissions and net fluxes of CO2 associated with the management of
agriculture soils,3 and CH4 and N2O emissions associated with agriculture residue burning.
Figure 9-1 shows Pennsylvania’s historical and projected GHG emissions from sources in the
agriculture sector for 1990 through 2020.
Relative to other sectors, Pennsylvania's agriculture sector contributes relatively low amounts of
GHG emissions to total statewide emissions. In 2000, the agriculture sector contributed about 8.4
million metric tons of carbon dioxide equivalent (MMtCO2e) emissions (about 3%) to
Pennsylvania’s total statewide gross GHG emissions (consumption basis). Within the agriculture
sector, agricultural soil management accounted for the largest source of emissions, representing
46% of total agricultural emissions and 1.4% of total statewide gross GHG emissions in 2000.
The contribution of other agricultural sources to total agricultural emissions include livestock
enteric fermentation (36%), manure management (18%), and burning of agricultural crop waste
Since 2000, agricultural sector emissions have remained fairly constant through 2009, and are
expected to follow a similar trend through 2020. Overall, emissions for the agricultural sector are
expected to increase slightly by about 0.6 MMtCO2e (approximately 7.3%) from 2000 to 2020.
1 Methane emissions from enteric fermentation are the result of normal digestive processes in ruminant and non-
ruminant livestock. Microbes in the animal digestive system breakdown food and emit CH4 as a by-product. More
CH4 is produced in ruminant