From seeds and soil to markets and manure, everything about how our food is grown, processed and distributed plays a role in emissions and climate change. How do we support practices that reverse the impact agriculture has on the climate crisis?
The global food system accounts for approximately one-third of manmade greenhouse gas emissions, from fertilizer production to the clearing of forests for large-scale plantations and livestock operations.
The main sources of greenhouse emissions from the food system include:
• Emissions from land use changes, which accounted for eighteen percent of the total global warming effect, mostly from the destruction of vital rainforests through burning and clearing and the elimination of wetlands and peat bogs to expand pasture for cattle, feed crops for livestock, and oil palm plantations.[i]
• Energy used in food production, which includes manufacturing and use of on-farm machinery, energy-intensive irrigation (by some estimates eating up 15 percent of total energy used in agriculture)[ii], as well as the energy used in the heating and cooling required of feedlots and meat manufacturing plants;
• Emissions from the production of farm chemicals and fertilizers, over half of which are used to grow crops for animal feed. Nitrogen fertilizer is notoriously energy-intensive to produce, requiring roughly 28,000 cubic feet of natural gas to produce a ton.[iii] (In the United States, emissions from fertilizer application, represents 72 percent of the nation’s man-made nitrous oxide emissions)[iv];
• Methane emissions from rice cultivation. Much of the world’s rice is grown in flooded paddies. The flooding (used to provide water to the crop and to help protect the rice crop from pests and weed pressure) means that the manure, soils and other organic matter on the fields are in an anaerobic environment, and decomposition of these materials and the soil emissions result in methane being produced and released into the atmosphere.[v]
Consumption and Distribution and Waste
• Methane emissions from landfills: Our uneaten and wasted morsels end up in landfills that emit greenhouse gases as the waste decomposes;
• Emissions from the distribution, transportation, or storage of food: These emissions can be particularly high for meat, since it’s especially energy-intensive to transport and store.[vi]
[i] N. H. Stern, The Economics of Climate Change: The Stern Review (Cambridge: Cambridge University Press, 2007).
[ii] David Pimentel and Marcia Pimentel, Food, Energy, and Society, 3rd ed. (Boca Raton, FL: CRC Press, 2008), 188.
[iii] Wen Huang, USDA, ERS, Personal Communication.
[iv] Environmental Protection Agency, “U.S. Greenhouse Gas Emissions and Sinks: 1990-2011,” ed. USEPA (2013), 37. Agricultural soils accounted for approximately 69.3 percent of N2O emissions in the United States in 2011.
[vi] Environmental Protection Agency, “U.S. Greenhouse Gas Emissions and Sinks: 1990-2011,” ed. USEPA (2013).