Working Group III: Mitigation

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3.6.2 Summary of the Second Assessment Report

Little has changed in the industrialized agricultural sector during the past few years apart from the continuing trends towards genetically modified crops and animals, and reduced chemical input production methods (Section Farming systems remain a major contributor of anthropogenic emissions, not just from energy inputs but mainly from methane from ruminants (cattle, goats and sheep), livestock wastes, rice paddy fields, and nitrous oxide from the application of nitrogenous fertilizers, and circulation of N within crop and livestock production. Land use change activities, such as the clearance of forests by burning and cultivation to provide more land for agricultural production with subsequent soil degradation, are also major contributors (Chapter 4). Carbon sequestration by soils continues to be quantified and estimates refined further, including the effects from reducing organic matter losses by changing to minimum tillage techniques. Improved farm management can result in lower emissions of CH4 and N2O and increased soil carbon uptake.

New energy saving technologies, such as ice bank refrigeration for milk cooling (CAE, 1996), continue to be developed, but need to be widely implemented if they are going to have any significant effects on global greenhouse gas emissions. Methods to reduce emissions by the agricultural sector are outlined in Section 3.6.4. Energy crop production continues to provide a possible alternative land use where suitable land is available and markets exist for the products.

3.6.3 Historic and Future Trends

Although on-farm energy intensity (GJ/ha) continues to increase, energy inputs per unit of production (GJ/t) have tended to decline in modern intensive industrialized agricultural systems, mainly caused by increasing crop yields (IPCC, 1996). The current trend in OECD countries is towards less intensive farming systems because of public concerns for animal welfare, reduced chemical inputs, and increasing demand for organically grown food. If this demand continues it could lead to reduced GJ/ha and also to lower GJ/t if yields can be maintained, (though this is generally not the case for low input farming). Conversely, in developing countries energy use (both GJ/ha and GJ/t) is increasing in attempts to increase yields (t/ha) by substituting machinery for manual labour, developing irrigation schemes, and improving crop storage systems to reduce losses. For example, Indian agricultural production has increased threefold since 1970 to 200Mt of food in 1998, whilst during this period animal energy/ha declined 35%, and diesel and electricity inputs increased by over 15 times (Prasad, 1999).

The development and introduction of biotechnology and gene technology could offer new chances to accelerate and support the traditional plant and animal breeding procedures. However, the conflict between food security and environmental risks is yet to be resolved. In developing countries uptake of transgenic technologies would require support of the farmers in adopting non-traditional techniques. If, following a comprehensive risk assessment, public confidence in producing genetically modified organisms is obtained, it could ultimately result in:

  • yield increases per hectare of food and fibre crops;
  • improved performance efficiency of livestock animals;
  • reduced inputs of agrio-chemicals and fertilizers because of new resistant cultivars; and
  • development of low input cultivars with improved nutrient and water use efficiency.

Energy inputs per unit of product could be reduced by around 10%-20% as a result, and methane and nitrous oxide emissions also lowered. For energy crops, improvements through traditional plant breeding techniques have barely begun. Opportunities for developing high yielding crops more suitable for energy purposes (such as high erucic acid oilseed rape) using genetic engineering techniques by transferring genes through recombinant DNA technology also have potential (Luhs and Friedt, 1998).

More difficult to predict are changes in diet and food consumption based on availability, quality, health, and environmental decisions. New protein sources will also impact on land use as will the growing of new crops to provide biomaterials specifically for manufactured products.

Social problems in rural areas continue to occur as does urban drift, particularly in developing countries, resulting from unemployment caused by substitution of manual labour by fossil fuel powered tractors and machinery. Rural economies are also struggling financially (even in developed countries where farm subsidies are available) because of current surpluses of many food and fibre commodities leading to low prices. Therefore, limited funds are available for investment in more modern, less energy intensive equipment. Further evaluation of combining traditional manual techniques with modern crops and scientific knowledge to improve sustainability is required. Possible removal of agricultural subsidies in Europe and the USA is a further threat to the future profitability of these rural regions (which may then need to be stimulated through a government development plan), but could have beneficial effects in terms of reducing greenhouse gas emissions (Storey, 1997). However, it will also be an opportunity for unsubsidized energy crops to compete more successfully with the more traditional uses of the land.

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