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New FAO estimates of greenhouse gas data show that emissions from agriculture, forestry and fisheries have nearly doubled over the past fifty years and could increase an additional 30 percent by 2050, without greater efforts to reduce them.
Agricultural emissions from crop and livestock production grew from 4.7 billion tonnes of carbon dioxide equivalents* (CO2 eq) in 2001 to over 5.3 billion tonnes in 2011, a 14 percent increase. The increase occurred mainly in developing countries, due to an expansion of total agricultural outputs.
Meanwhile, net GHG emissions due to land use change and deforestation registered a nearly 10 percent decrease over the 2001-2010 period, averaging some 3 billion tonnes CO2 eq/yr over the decade. This was the result of reduced levels of deforestation and increases in the amount of atmospheric carbon being sequestered in many countries.
Sources of agricultural emissions
The largest source of GHG emissions within agriculture is enteric fermentation - when methane is produced by livestock during digestion and released via belches - this accounted in 2011 for 39 percent of the sector's total GHG outputs. Emissions from enteric fermentation increased 11 percent between 2001 and 2011.
Emissions generated during the application of synthetic fertilizers accounted for 14 percent of agricultural emissions (725 Mt CO2 eq.) in 2011, and are the fastest growing emissions source in agriculture, having increased some 37 percent since 2001.
Greenhouse gases resulting from biological processes in rice paddies that generate methane make up 10 percent of total agricultural emissions, while the burning of savannahs accounts for 5 percent.
Friday April 11, 2014/ FAO.
http://www.fao.org/
