The mitigation potential of a suite of agricultural practices that reduce emissions associated with farming and increase carbon storage is estimated to be 1,500 to 1,600 million tonnes of carbon dioxide equivalent (MtCO2e) per year at a carbon price of USD 20 per tCO2e. The mitigation potential through land use change is estimated to be a further 1,550 MtCO2e per year.

Smith et al., 2008

Data from Smith et al., 2008

Extra facts

  • The global economic potential for agricultural mitigation depends on carbon prices.
  • Agriculture’s overall potential to mitigate carbon (excluding biomass and fossil fuel offsets), is projected to be approximately 5,500-6000 MtCO2e per year by 2030 (Smith 2012). The price of carbon determines the global economic potential for agricultural mitigation—the higher the price, the higher the potential:
    • USD 0-20 per tCO2e: 1500–1600 MtCO2e per year (~3.0% of total global emissions)
    • USD 0-50 per tCO2e: 2500–2700 MtCO2e per year (~4.5% of total global emissions)
    • USD 0-100 per tCO2e: 4000–4300 MtCO2e per year (~7.5% of total global emissions)
    • (Smith et al. 2008)

  • The global economic potential of mitigation through land use change (avoided deforestation and degradation, reafforestation and restoration) is estimated to be between 1,270 and 4,230 MtCO2e per year in 2030 (at carbon prices up to USD 100 per tCO2e). About 1,550 MtCO2e per year can be achieved at a cost under USD 20 per tCO2e (Nabuurs et al. 2007).
  • Cropland management is a key agricultural mitigation practice. It includes the optimization of nutrient use (including organic and inorganic fertilizers) and the incorporation of nitrogen-fixing legumes into crop rotations.
  • Mitigation can be pursued by improving productivity—namely, approaches that increase the yield of edible output per unit of emissions generated, including changes in crop and animal breeding, feed optimization and dietary additives and pest and disease management.
  • Managing and benefiting from agricultural outputs, including manure and plant biomass, composting and the use of anaerobic digestion, can contribute to potential mitigation.
  • Reducing the carbon intensity of fuel inputs through energy efficiency improvements and the use of alternative fuels such as biomass, biogas, wind and solar power is another mitigation approach (Garnett 2011).
  • The restoration of cultivated organic soils and degraded lands, along with land use change and agroforesty also contributes to mitigation potential (Smith et al. 2008).
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Methods, caveats and issues

  • There is uncertainty about the measurement of the agriculture sector’s mitigation potential.
  • Global technical mitigation potential was calculated using per-animal or per-area estimates of mitigation potential for each greenhouse gas and multiplying this by the area available for that practice in each region. Economic potential of the mitigation strategies was calculated using Marginal Abatement Curves form the US EPA 2006 to define the level of implementation for each practice in each region for different carbon prices (Smith et al. 2008).
  • Many mitigation opportunities use current technologies and can be implemented immediately, but technological development will be critical to increasing the options for and efficacy of future agricultural mitigation (Smith et al. 2007: 499). Despite much potential for mitigation in agriculture, very little progress has been made since 1990 due to implementation barriers that incentives could overcome (Smith et al. 2008).
  • The portfolio of mitigation strategies varies over time due to the limited ecological capacity of sequestration-related strategies and the limited market penetration potential of capital intensive strategies like biofuels (Smith et al. 2008).
  • Mitigation estimates do not factor in future growth trajectories. While the Intergovernmental Panel on Climate Change (IPCC) identifies significant mitigation potential for agriculture, when set against total agricultural emissions, the achievable reductions (even assuming a high carbon price) only amount to about 30 percent of the total impact.
  • As food production increases, absolute emissions will grow while opportunities to sequester carbon in the soil will dwindle (Garnett 2011).
  • Mitigation approaches must be tailored to specific contexts; successful practices that work in one location or situation may be counter-productive in another (Smith et al. 2008).
  • It is not always the case that the effects of the measures for reducing enteric methane production in livestock can be additive when applied simultaneously (Smith et al. 2008).
  • Emissions from manure management might be curtailed by altering feeding practices or composting manure, but if aeration is inadequate during composting, curtailed emissions may be offset by substantial CH4 emissions (Smith et al. 2008).
  • Non-livestock measures often only benefit one gas (e.g., agro-forestry benefits CO2 sequestration) whereas others offer a trade-off between gases (e.g., restoration of organic soils can store CO2, but may increase the release of N2O from anaerobic processes). These trade-offs make the net mitigation benefit particularly difficult to calculate, which is why the standard deviation of most figures is quite large (Smith et al. 2008).
  • Rice cultivation, as a significant emitter of CH4, has a high potential for mitigation. But more research is needed to combine both carbon sequestration methods with lower N2O emissions (Smith et al. 2008).
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Sources

  • Lipper L, Neves B, Wilkes A, Tennigkeit T, Gerber P, Henderson B, Branca G, Mann W. 2011. Climate change mitigation finance for smallholder agriculture: a guide book to harvesting soil carbon sequestration benefits. Rome: Food and Agriculture Organization of the United Nations. (Available from http://www.fao.org/docrep/015/i2485e/i2485e00.pdf)
  • Garnett T. 2011. Where are the best opportunities for reducing greenhouse gas emissions in the food system (including the food chain)? Food Policy 36:S23-32.
  • Nabuurs GJ, Masera O, Andrasko K, Benitez-Ponce P, Boer R, Dutschke M, Elsiddig E, Ford-Robertson RJ, Frumhoff P, Karjalainen T, Krankina O, Kurz WA, Matsumoto M, Oyhantcabal W, Ravindranath NH, Sanz Sanchez MJ, Zhang X. 2007. Forestry. In: B Metz, OR Davidson, PR Bosch, R Dave, LA Meyer, eds. Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press. (Available from http://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-chapter9.pdf)
  • Smith P, Martino D, Cai Z, Gwary D, Janzen H, Kumar P, McCarl B, Ogle S, O’Mara F, Rice C, Scholes B, Sirotenko O. 2007. Agriculture. In: B Metz, OR Davidson, PR Bosch, R Dave, LA Meyer, eds. Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press. P. 498-540. (Available from http://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-chapter8.pdf)
  • Smith P, Martino D, Cai Z, Gwary D, Janzen H, Kumar P, McCarl B, Ogle S, O’Mara F, Rice C, Scholes B, Sirotenko O, Howden M, McAllister T, Pan G, Romanenkov V, Schneider U, Towprayoon S, Wattenbach M, Smith J. 2008. Greenhouse gas mitigation in agriculture. Philosophical Transactions of the Royal Society B 363:789 – 813. (Available from http://rstb.royalsocietypublishing.org/content/363/1492/789.full)
  • Smith P, Olesen JE. 2010. Synergies between the mitigation of, and adaptation to, climate change in agriculture. Journal of Agricultural Science 148:543–552.
  • Smith P. 2012. Agricultural greenhouse gas mitigation potential globally, in Europe and in the UK: what have we learnt in the last 20 years? Global Change Biology 18:35–43.
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