Page 85 - FAO-IPCC Expert meeting on climate change

Appendix 01: Speakers’ summary notes
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Organic soils are an important subset of agricultural soil emissions. These soils represent a relatively small portion of the agricultural area globally, but because of the high carbon content of peat and muck soils, they emit large quantities of carbon per hectare. These soils cover around 3% of the land area, but they contain at least 30% of all soil carbon. In order to grow crops, these soils are drained, which decreases CH4 emissions, but as the previously anaerobic organic materials are exposed to higher levels of oxygen, they mineralize and carbon is lost as CO2.
Over 25 million hectares of organic soils have been drained worldwide for agriculture use, which is about 7% of the total area. Of the drained areas, 60 percent is in boreal and cool temperate regions, 5 percent is in warm temperate regions, and 34% is in the tropics, mostly in Southeast Asia. The majority of these drained lands are being used for crop production. Emissions from these agricultural areas are estimated to be almost one billion tonnes CO2 eq annually. Carbon dioxide accounts for around 85 percent of these emissions, with the balance made up by N2O emissions. The use of fire to clear land, particularly in Southeast Asia, creates additional organic soil emissions. Emissions of N2O also increase significantly as organic matter is mineralized and fertilization of these areas can exacerbate this situation.
The outlook for emissions from organic soils is uncertain. There are no global assessments of the drivers of peatland conversion and no projections for temperate and boreal conversion. In Southeast Asia, expansion of industrial and smallholder oil palm production is likely in the future, driven by markets for both edible oils and biofuels. Indonesia has adopted a policy which sets a goal for biofuels to constitute 25 percent of its national energy mix by 2025. Biodiesel from crude palm oil will be a significant part of the strategy to achieve this goal. In 2010, about 22 percent of plantations in Indonesia were on peat soils, so meeting the national goals require expansion of palm oil production. While the economics of meeting these production targets suggest a continued role for peatlands in future production, the government has recently created a federal agency to better regulate these regions.
Assessment of emissions related to aquaculture was new to the 5th Assessment Report. Production of fish and shellfish in aquaculture systems exceeded 55 million tonnes in 2010 and accounts for nearly half the fish consumed by humans. One of the major emissions impacts of this production is N2O, with emissions predicted to increase to about 6% of anthropogenic N2O emissions by 2030. Aquaculture also leads to significant mangrove destruction which results in large losses of carbon from both the biomass and sediments. Mangrove forests store between 500 and 1000
tC ha-1 and much of this carbon is lost when they are converted to aquaculture. Global estimates suggest that between 20% and 35% of mangrove area has been lost since 1980; loss rates are around 1% per year and some estimates are as high as 2–8% per year. Urbanization, coastal development, and unsustainable harvesting is responsible for a large portion of mangrove destruction. However, clearing of mangroves for shrimp culture is responsible for as much as 38% of global mangrove loss and other forms of aquaculture account for an additional 14%. Aquaculture ponds may also be responsible for carbon sequestration in sediments, with estimated accumulation at the global scale on the order of 17 Mt y-1.
In the absence of a comprehensive global assessment of the food system that quantifies the emissions related to processing of food, case studies present useful information. One analysis of the UK food system shows that production accounts for about 45% of total emissions. Food transport, packaging, and processing accounts for about 31% of emissions and food use and disposal accounts for 24%. In the US, the highest levels of energy use in the food industry are associated with animal slaughtering and processing, wet corn milling, and fruit and vegetable preservation. AR5 reported that these processes account for 19%, 15%, and 14% of total energy use, respectively. A global assessment in the dairy sub-sector focused on butter, concentrated milk, and milk powder and estimated annual emissions of
over 128 MtCO2. Efficiency gains in some countries could eventually lead to reductions on the order of 9 to 14
MtCO2 if measures were implemented to lower specific energy consumption significantly in at least half of dairy plants worldwide. These case studies illustrate that there are efficiencies to be gained with energy use in food processing through improved technologies and processes. Additional efficiencies need to be built into national energy systems.
This presentation and the ones that follow show that while many of the largest issues related to agricultural emissions were well captured in AR5, there is sufficient new scientific material to contribute to an expanded understanding of these issues in a special report on climate change, desertification, land degradation, sustainable land management, food security, and GHG fluxes in terrestrial ecosystems.
FAO-IPCC Expert meeting on climate change, land use and food security