Global methane and nitrous oxide emissions and reduction potentials in agriculture.

Agricultural activities account for almost 50 and 60% of the total anthropogenic CH4 and N2O emissions, respectively in 2005 (IPCC. 2007. Climate change 2007. Mitigation of climate change, Working Group III contribution to the fourth assessment report of the intergovermental panel on climate change summary for policymakers and technical summary). Thus, we developed an integrated model to estimate global CH4 and N2O emissions and reduction potentials related to agricultural production from 2000 to 2030. In this model, the amounts of implemented countermeasures for greenhouse gas mitigation are calculated as an optimal problem to minimize the total reduction costs under several marginal abatement costs. As a result, we determined the most cost-effective countermeasures, regions and emission sources with high reduction potentials in 2030. Global CH4 and N2O emission in agricultural activities was 4.0 GtCO2 eq/year in 2000 and will increase to approximately 40% (up to 5.6 GtCO2 eq/year) by 2030. Moreover, in 2030, the total maximum reduction potential will be about 1.4 GtCO2 eq/year which accounts for 35% of the total of CH4 and N2O emissions in agriculture in 2000. Particularly, livestock manure management and rice paddy are expected to be emission sources that have high reduction potentials. We identified a “daily spread of manure” as one low-cost countermeasure with high reduction potential based on the analysis of reduction potentials by countermeasures. [ABSTRACT FROM AUTHOR]