Greenhouse gas emissions from agriculture, forestry and fisheries are on the rise, nearly doubling over the past 50 years, a new report released last week by the United Nations Food and Agriculture Organization says.
Emissions from crop and livestock production grew from 4.7 billion tonnes of carbon dioxide equivalents in 2001 to more than 5.3 billion tonnes in 2011, a 14% increase. The increase occurred mainly in developing countries, due to an expansion of total agricultural outputs.
Without efforts to reduce ag & related industry GHG emissions, FAO says they could increase an additional 30% by 2050, without greater efforts to reduce them.
In contrast, net GHG emissions due to land use change and deforestation registered a nearly 10% decrease over the 2001-2010 period, averaging some 3 billion tonnes CO2 equivalents per year over the decade.
FAO said this development was the result of reduced levels of deforestation and increases in the amount of atmospheric carbon being sequestered in many countries.
FAO's report says over the 2001-2010 period, agriculture, forestry and other land use emissions totaled 5 billion tonnes CO2 eq/yr from crop and livestock production; 4 billion tonnes CO2 eq/yr due to net forest conversion to other lands; 1 billion tonnes CO2 eq/yr from degraded peatlands; and 0.2 billion tonnes CO2 eq/yr by biomass fires.
FAO's data based on country reports show that while emissions continue to increase, they are not growing as fast as emissions from fossil fuel use in other sectors, so the share of AFOLU out of total anthropogenic emissions is actually decreasing over time.
Ag emissions sources
Livestock. The largest source of GHG emissions within agriculture is enteric fermentation – when methane is produced by livestock during digestion. This accounted in 2011 for 39% of the sector's total GHG outputs, and amounted to 11% between 2001 and 2011.
Fertilizer. Emissions generated during the application of synthetic fertilizers accounted for 13% of agricultural emissions in 2011, and are the fastest growing emissions source in agriculture, having increased some 37% since 2001, FAO says.
Rice production/burning. Greenhouse gases resulting from biological processes in rice paddies that generate methane make up 10% of total agricultural emissions, while the burning of savannahs accounts for 5%.
Area of origin
In 2011, 44% of agriculture-related GHG outputs occurred in Asia, followed by the Americas (25%), Africa (15%), Europe (12%), and Oceania (4%), according to FAO's data.
This regional distribution was fairly constant over the last decade. In 1990 however, Asia's contribution to the global total (38%) was smaller than at present, while Europe's was much larger (21%).
How ag uses energy
The new FAO data also provide a detailed view of emissions from energy use in the agriculture sector generated from traditional fuel sources, including electricity and fossil fuels burned to power agricultural machinery, irrigation pumps and fishing vessels.
These emissions exceeded 785 million tonnes of CO2 eq. in 2010, having increased by 75% since 1990.
Options for response
Designing responses will require detailed assessments of both emission data and mitigation options, FAO says.
FAO's Francesco Tubiello says the data marks the most comprehensive data yet. "Up to now, information gaps have made it extremely difficult for scientists and policymakers to make strategic decisions regarding how to respond to climate change," he said. ''Data on emissions for AFOLU activities support member countries in better identifying their mitigation options and enable their farmers to take faster and more targeted climate-smart responses."