19. Reducing GHG Emissions from Traditional Livestock Systems to Mitigate Changing Climate and Biodiversity

Climate change (CC) directly impacts the economy, ecosystems, water resources, weather events, health issues, desertification, sea level rise, and even political and social stability. The effects of CC affect different groups of societies differently. In Tanzania, the effects of CC have even acquired a gender dimension, whereby women are viewed as more vulnerable than men because of socioeconomic and historic barriers. CC is largely caused by anthropogenic activities, including those that increase the concentrations of greenhouse gases (GHGs) in the atmosphere. Recent findings indicate that the livestock sector is responsible for 18 % of GHG emissions measured in the CO₂ equivalent. Moreover, some gases emitted by livestock have higher potential to warm the atmosphere than CO₂ and have a very long atmospheric lifetime. Methane (CH₄) has 23 times the global warming potential (GWP) of CO₂, whereas nitrous oxide (N₂O) has 296 times the GWP of CO₂. It is now estimated that the atmospheric concentrations of CH₄ and N₂O are increasing at a rate of approximately 0.6 % and 0.25 % per year, respectively. Cattle may emit CH₄ from enteric fermentation equivalent to 2–12 % of the ingested energy, whereas produced manure can emit N₂O up to 1.25 % of its weight. The estimated total CH₄ and N₂O emissions from Tanzanian ruminants stand at 26.17 Gg and 0.57 Gg, respectively. In this paper, we first very briefly review emissions of GHGs from different livestock production systems in Tanzania with the view of identifying the main hot spots. Then, we concentrate on the available adaptation options and the limitations on the adoption of such adaptation options in Tanzania. Emission of these GHGs per unit product varies with the level of intensification, the types of livestock kept, and manure management. Intensification of livestock production reduces the size of the land required to sustain a livestock unit and frees up the land necessary for carbon sequestration. In Tanzania, such intensification could take the form of the early harvesting and storing forage for dry-season feeding. The advantage of this intervention is twofold: young harvests have higher digestibility and emit less CH₄ when fed to ruminants than mature lignified forage; use of stored roughage in the dry season will reduce the desertification of rangeland and deforestation that occur when livestock search for pastureland. Dry-season supplementation of ruminants with energy and protein-rich diets will reduce CH₄ emission. The chemical treatment of crops byproducts will increase the crops’ digestibility and reduce CH₄ emission from ruminants. Crossbreds of indigenous and exotic breeds are more efficient converters of feed into products like meat and milk, with less GHG emitted per unit product. The use of manure for biogas production will reduce the emission of both CH₄ and N₂O into the atmosphere. Shifting from liquid to solid manure management has the potential to reduce CH₄ emissions. Most of these interventions, however, are not cost neutral – enhancing awareness alone will not lead to their widespread adoption. In the absence of subsidies, the adoption of these interventions will depend on the relative cost of other options. Although some traditional livestock systems in Tanzania are already coping with the impact of CC, such efforts are handicapped by inadequate resources, poor coordination, and implementation of competing measures.